EP0090804A1 - Method and apparatus for measurements of channel operation - Google Patents

Method and apparatus for measurements of channel operation

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Publication number
EP0090804A1
EP0090804A1 EP19810903022 EP81903022A EP0090804A1 EP 0090804 A1 EP0090804 A1 EP 0090804A1 EP 19810903022 EP19810903022 EP 19810903022 EP 81903022 A EP81903022 A EP 81903022A EP 0090804 A1 EP0090804 A1 EP 0090804A1
Authority
EP
European Patent Office
Prior art keywords
channel
time
subchannel
clock
central processor
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19810903022
Other languages
German (de)
French (fr)
Inventor
Roger Louis Cormier
Robert James Dugan
Richard Roland Guyette
Ronald Lee Hankison
Ming C. Hao
Arthur Louis Levin
George Albert Mcclain
Paul John Wanish
Carl Zeitler, Jr.
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
International Business Machines Corp
Original Assignee
International Business Machines Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by International Business Machines Corp filed Critical International Business Machines Corp
Publication of EP0090804A1 publication Critical patent/EP0090804A1/en
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F11/00—Error detection; Error correction; Monitoring
    • G06F11/30—Monitoring
    • G06F11/34—Recording or statistical evaluation of computer activity, e.g. of down time, of input/output operation ; Recording or statistical evaluation of user activity, e.g. usability assessment
    • G06F11/3409—Recording or statistical evaluation of computer activity, e.g. of down time, of input/output operation ; Recording or statistical evaluation of user activity, e.g. usability assessment for performance assessment
    • G06F11/3419—Recording or statistical evaluation of computer activity, e.g. of down time, of input/output operation ; Recording or statistical evaluation of user activity, e.g. usability assessment for performance assessment by assessing time
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F11/00—Error detection; Error correction; Monitoring
    • G06F11/30—Monitoring
    • G06F11/34—Recording or statistical evaluation of computer activity, e.g. of down time, of input/output operation ; Recording or statistical evaluation of user activity, e.g. usability assessment
    • G06F11/3466—Performance evaluation by tracing or monitoring
    • G06F11/3485—Performance evaluation by tracing or monitoring for I/O devices
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F11/00—Error detection; Error correction; Monitoring
    • G06F11/30—Monitoring
    • G06F11/34—Recording or statistical evaluation of computer activity, e.g. of down time, of input/output operation ; Recording or statistical evaluation of user activity, e.g. usability assessment
    • G06F11/3466—Performance evaluation by tracing or monitoring
    • G06F11/349—Performance evaluation by tracing or monitoring for interfaces, buses

Definitions

  • This invention relates to a method and apparatus for measuring the time that is taken by components of a data processing system for channel operations.
  • a central processor includes a main store and a computing engine or engines that execute system programs and user programs that are located in main store.
  • a channel includes a channel store and a channel processor that handles I/O (input/output) operations of peripheral devices.
  • the channel processor executes an I/O program that is located in main store and is made up of commands.
  • the system control program executes I/O instructions. For example, an I/O instruction and the associated protocol to start an I/O operation identifies a particular I/O device, a Location in main store when the channel program is located, and a Location in main store where the channel is to save or fetch data.
  • the channel processor also performs operations relating to scheduling the I/O devices to handle particular tasks as the devices and associated data paths become available.
  • a general object of the invention is to provide a new and improved method and apparatus for measuring the time that is required for channel operations.
  • Measurement data can also be used dynamically to schedule tasks to be performed on particular components that happen to be less heavily used and to avoid data paths that are more heavily used.
  • processor and channel functions have been measured by programs that run on the central processor.
  • the processor has a time ⁇ f day clock and the measurement program accesses the time of day clock and keeps track of the starting times and the accumulated times for selected operations that can be signaled to the monitoring program. See "OS/VS2 MVS Resource Management Faclity (RMF) General Information Manual GC28-0921-2", available from International Business Machines Corporation.
  • the method and apparatus of this invention are particularly adapted to perform measurements on a channel operation that is started by a machine language instruction called Start Subchannel.
  • the instruction and the associated protocol identify to the channel a subchannel and an associated I/O device and the main storage location of the channel program. This information is passed to the channel, and the channel then schedules the I/O operation in the same general way that the operation would otherwise be scheduled and dispatched by a control program in the central processor, and initial selection then takes place.
  • One of the objects of this invention is to measure the delays between the execution of Start Subchannel in the central processor and Initial Selection which later takes place independently in the channel.
  • the invention includes a time of day clock that is synchronized with the time of day clock of the central processor.
  • Means is provided in the I/O Supervisor program of the operating system of the central processor to read the time of day clock of the central processor and to store this value in a suitable location that is accessible to the channel.
  • Means is provided in the channel program that performs initial selection to read the time of day clock of the channel and to fetch the value of the time of day clock that was stored by the central processor and to calculate the time difference and to store this difference in a suitable location. This time is called Function Pending Time. After Initial Selection the device typically disconnects from the channel and later reconnects and continues, typically with further disconnects, until the channel interrupts the central processor to signal that the operation has been completed. This point in the channel operation is called Channel End (because the channel sets a status bit that is called Channel End) .
  • the accumulation of times during which the device is connected is called device connect time.
  • the channel provides the device connect time in one form that is suitable for use such as billing the individual user of the subchannel and it accumulates this time in a second form that is suitable for use in manually or automatically planning or scheduling channel resources.
  • the invention also provides means in the channel program for measuring the time between Start Subchannel and Channel End which is called Function Active Time. These measurements are useful directly and they can be used in combination to calculate other useful functions.
  • the channel has means in the routine for handling ending status to store Function Pending Time, Function Active Time and Device Connect Time in a Subchannel Measurement Block location in main store that is preassigned to the particular subchannel.
  • the invention also provides means including a new machine language instruction called Set Channel Monitor (SCHM) for enabling the monitor function.
  • This instruction contains the starting address of the subchannel measurement blocks which the channel uses for storing the monitored time values.
  • the channel has means for storing this address. When this address is all zeros (or any predetermined value that is never used as the starting address) , the channel does not measure channel operations.
  • Means is also provided for selectively enabling or disabling the measurement function for each subchannel (when the measurement function is enabled by the Set Channel Monitor Instruction) .
  • a data block for each subchannel that is called the Subchannel Information Block contains a two bit field that identifies one of three modes of monitoring operations. (One of the four possible codes is not used.) In one mode, the monitor function is disabled for the subchannel. In another mode only conventional device connect time is measured and is stored in the Sxibchannel Status Word. In another mode all of the subchannel measurements that have been described are collected and stored.
  • the Subchannel Information Block is also arranged to store an address offset or displacement to the starting address in the instruction Set Channel Monitor the channel program has means for adding the offset to the starting address for accessing the Subchannel Measurement Block.
  • Fig. 1 is a timing diagram of an I/O operation showing points at which times are recorded and the time intervals that are measured.
  • Fig. 2 shows the-, circuit of a clock that is used by the channel in recording times.
  • Figs. 3A-D show components of the channel and the interconnecting signals in a representative measurement operation.
  • Fig. 4 is a diagram showing the format in storage of the channel measurement parameters and the associated system of addresses to these storage locations.
  • the invention is preferably adapted to be used with a system in which a central processor (which may have several engines) operates with a single channel (which also may have several engines) and in which each device has a separate subchannel (as is conventional) .
  • the processor starts an I/O operation by means of an instruction that is called Start Subchannel.
  • Start Subchannel In the execution of this instruction. the channel is given the identification of the device and the address of the channel program in main store (both steps are conventional) .
  • the central processor is then free to branch to some independent operation.
  • Fig. 1 shows Start Subchannel as one of the measurement points in the system of this invention.
  • Start Subchannel The information in the instruction Start Subchannel is put onto a queue in channel storage (sometimes called bump storage) and the channel schedules the resources that are required to establish the data path of the subchannel in the same general way that other tasks are scheduled by a processor.
  • channel storage sometimes called bump storage
  • the channel schedules the resources that are required to establish the data path of the subchannel in the same general way that other tasks are scheduled by a processor.
  • the channel contacts the device controller in a conventional process that is called initial selection.
  • Fig. 1 shows this point called successful initial selection.
  • the time from Start Subchannel to Successful initia.1 selection is called Function Pending time.
  • Function Pending Time is useful because it may be long for some devices that are heavily used and shorter for other devices that are less heavily used. For example, a number of disks or other similar may provide a pool of storage space that the system control program allocates temporarily to programs of users. This measurement is useful in allocating storage space from devices that currently have shorter times for function pending.
  • the channel executes the first command.
  • this command tells the disk controller to position the disk head at a particular track for a read or write operation.
  • This mechanical operation is relatively slow, and the device controller is ordinarily programmed to disconnect from ' the channel for this operation.
  • This point in Fig. 1 is indicated by the legend Disconnect.
  • the device When the device is ready to execute a command of the channel program, it reconnects. Typically a device disconnects and reconnects several times after Start Subchannel and
  • Fig. 1 shows two representative Device Connect times.
  • Device connect time is commonly measured for each user. As will be explained later, the system of the drawing provides this function on a user basis and also provides accumulated connect time for an individual device.
  • Fig. 1 also shows Channel End and Device End which are conventional points in an I/O operation.
  • the time from Start Subchannel to Channel End is measured by the apparatus of this invention and is called Function Active time.
  • Device connect times are each useful individually, and in addition they can be combined to calculate other times.
  • the channel is provided with a clock 12 that is used in the measurement operations of this invention.
  • the clock conventionally comprises a number of counter stages that are connected to be incremented by a stepping or advance pulse that appears periodically on a line 13 at intervals that correspond to the resolution that is desired in the channel measurements.
  • the channel clock is synchronized with the time of day clock 14 of the associated processor.
  • the system time of day clock can be read by an instruction called Store Clock (STCK) which includes an address of a sixty-four bit location in main store where the current value of the time of day clock is to be stored. See "IBM System/370 Principles of Operation: GA22-7000, pages 141, 142.
  • STCK Store Clock
  • This clock also has a number of counter stages and an oscillator 15 that steps the counter in increments that represent units of time.
  • One stage of the counter is selected as appropriate to the degree of resolution that is desired in the channel measurements, and in the preferred system this interval is one hundred twenty-four microseconds.
  • Line 13 connects the one hundred twenty-four microsecond output of the system time of day clock to the advance input of the channel clock.
  • Another time signal of the system time of day clock is connected by a line 17 to form a reset for the channel clock.
  • This time unit is eight seconds in the preferred system.
  • This reset from the system time of day clock keeps the channel clock identical to the corresponding stages of the -system time of day clock (after an initial reset operation) so that an operation can be timed partly from the system time of day clock and partly from the channel clock.
  • c-:.: ⁇ also synchronizes the clocks of different channels that are part of a multi-processor system because the time of day clocks of the different processor systems are independently synchronized. (There is one channel for each processor system and a processor system has one or more processors (not shown) that operate under a common control program.
  • Eight seconds is conveniently represented by a sixteen bit value and it is long enough to include virtually any possible I/O operation that is to be measured.
  • the channel clock is arranged to be read by an instruction or a micro-instruction of the channel processor and the clock value is stored in the channel store at a location that is specified in the instruction.
  • This structure is similar to the structure of the system time of day clock and is illustrated in Fig. 2 by a signal Store Clock on a line 18, the channel store 20 and a system of gates 21 that transfers the channel clock value to a channel store location designated by an address on a line 22 from the instruction decoder.
  • control store 25 the control store 25 and the arithmetic and logic unit (ALU) 26 will be familiar from standard operations of these components.
  • ALU arithmetic and logic unit
  • Fig. 3A initial selection has been made and is signaled by a device on a tag line 30 called Service In.
  • This signal causes the channel to execute a microprogram that is located in control store 25.
  • This otherwise conventional microprogram includes instruction means for reading the channel clock 12 and loading its current value into a predetermined location 33, arbitrarily called Start Time, in channel store 20.
  • the address of this storage location and a field calling for a store operation are carried in the microcode instructions as is conventional and as line 35 in the drawing represents.
  • the microcode also supplies the signal Store Clock on line 18.
  • the channel time is stored. Since the speed of the channel processor is very fast in relation to the resolution of the channel clock, it will ordinarily make little difference where this measurement operation is located in the routine for handling Service In.
  • the fall of Service In conventionally signals device disconnect and causes the channel to begin a routine to respond to this condition.
  • this conventional routine contains microinstruction means for reading the channel clock. subtracting the value from the value stored in Fig. 3A, and storing the difference in a predetermined location of channel store that is called Accumulate.
  • the drawing is representative of various ways in which this operation can be performed.
  • a microinstructio or a series of microinstructions read the channel clock and apply the clock value at one input of ALU 26 and also fetch from channel store 20 the clock value stored in the dperation of Fig. 3A and apply this value to the other input of ALU 26 and also control ALU 26 to perform a subtraction and to load the difference into a register 38 or an equivalant location in channel store 20.
  • Fig. 3C is a continuation of this operation, as the signal Next Step to the control store signifies.
  • the channel store is accessed at the location Accumulate which holds the accumulated time for any previous connect/disconnect sequence.
  • This value and the difference in register 38 are summed and stored in a location 39.
  • the sum in register 39 is stored in the accumulator location in channel store.
  • the operations of Fig. 3A through 3D are repeated and the device connect time accumulates in the Accumulate location.
  • the channel clock may be reset between the step of Fig. 3A and the step of Fig. 3B so that the difference in register 38 is a negative value.
  • the reset value of the channel clock (eight seconds in the specific example) is added to the negative value.
  • the conventional techniques for testing for a negative value and either adding or not adding the eight seconds will be readily understood without a specific example.
  • Start Subchannel time is recorded by the central processor by conventional instructions in the routine that executes Start Subchannel.
  • the time of day clock can be stored in any convenient location that is accessible to the central processor and to the channel, such as a location in main store that is otherwise assigned to the operating system or to a location in channel store.
  • This operation of the central processor can be thought * of as a counterpart of the operation shown in Fig. 3A.
  • Channel End is signaled to the channel by the device and in response to this signal the channel reads the channel clock and calculates Function Active time in the way that has been described for Function Pending time. The channel also updates the device connect time as already described.
  • Subchannel measurement operations take place when the central processor executes an I/O instruction called Set Channel Monitor (SCHM) .
  • SAM Set Channel Monitor
  • the instruction has the familiar format of a sixteen bit field for the operation code and a sixteen bit field for an address in the form of a base B2 and a displacement D2.
  • the channel stores the address as represented by block 41. This address (if it is not all zeros) points to a location in the central processor main store 43 where the measurement data is to be stored for each subchannel that is to be measured.
  • Fig. 4 shows the format for storing the measurement parameters.
  • Each subchannel has four word locations (of thirty-two bits each) 45, 46, 47 and 48 for the measurement parameters.
  • Each channel also has an extended measurement area of four additional words (not shown) for additional measurement parameters that may be desirable.
  • OMPI is useful in the operation and organization of the data processing system.
  • the parameters can also be used by a program that allocates system resources ' as has already been described.
  • the channel maintains a block for each subchannel that is called the Subchannel Information Block (SCHIB) .
  • This block includes an address offset that is combined with the address in register 41 to point to the measurement block for the particular subchannnel. Addressing of this kind is widely used and does not require detailed explanation.
  • the SCHIB*s can be assigned to any convenient location in channel store 20.
  • the channel also maintains a Subchannel Status word (not shown) for each subchannel which contains for example the CCW Address and is generally similar to a Channel Status Word. Device connect time is also stored in this status word.
  • the measurement operation is inhibited.
  • the instruction can be thought of as having one form to enable measurement and a second form to disable measurement.
  • the measurement is enabled by a latch that is set by this address and. reset by the all zeros address or equivalently by a corresponding bit that is set in a control word of the channel engine.
  • C. a .-Pl relation to Fig. 4 include instructions to test this status and to execute the measurement instructions or to branch around them according to the condition established by Set Channel Monitor.
  • routines that include Set Channel Monitor and associated routines that set up the SCHIB's are enabled or disabled for a particular measurement in the same way that the operating system is selectively controlled to provide or not to provide available functions.
  • Means is also provided for disabling an individual subchannel for measurement or for enabling one of two measurement modes.
  • This condition for a subchannel is controlled by a two bit field in its SCHIB and this field is tested by the techniques described for Set Channel Monitor.
  • the subchannel is enabled for the measurements that are shown in main store 43 in Fig. 4 and for reporting device connect time in the Subchannel Status Word.
  • the device connect time of the Subchannel Status Word is measured.
  • the channel includes microprogram means to store device connect time, Function pending time, and Function Active time, (according to the mode set in the SCHIB and whether the channel is enabled for measurement)
  • the channel fetches, increments and restores the Sample Count and the SSCH chount shown in Fig. 4.
  • SSCH count is incremented in either active measurement mode, whenever device connect time is stored. Sample Count is stored only when Function Active and Function Pending are also stored. The conditions of the microcode will be apparent without detailed explanation.
  • the hardware of the channel and the central processor correspond specifically to the IBM 3081 but the channel clock of this invention and its connection to the conventional processor clock is applicable to various processor and channel designs.
  • This processor has a single channel, but the invention is applicable to systems that conceptually have more than one channel.
  • Other aspects of the invention have been illustrated by the incorporation of new microcode routines in the otherwise normal microprograms of the channel.
  • the actual microprograms can be implemented in various ways. Thus, those skilled in the art will recognize many applications for this invention and appropriate variations within the spirit of the invention and the scope of the claims.

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  • Quality & Reliability (AREA)
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Abstract

Un canal pour un système de traitement de données est pourvu d'une horloge (12) de l'heure du jour qui est synchronisée avec l'horloge de l'heure du jour (14) du processeur central associé. Tant le processeur central que le processeur de canal enregistrent les temps d'évènements particuliers, et le canal utilise ces temps pour calculer deux temps appelés "fonction en cours" et "fonction active". Les deux temps commencent lorsque le processeur central exécute une instruction pour commencer une opération d'entrée/sortie. La fonction en cours se termine lorsque le canal a mené à bien une sélection initiale. Ce temps présente les retards par le processeur de canal dans la programmation des ressources du canal pour les opérations d'entrée/sortie. La fonction active se termine à l'extrémité du canal. Une nouvelle instruction, "set channel monitor" (40), permet de valider ou d'invalider ces mesures. Un bloc d'informations (SCHIB) pour chaque sous-canal définit un ou plusieurs modes de mesures pour un sous-canal ou invalide la mesure d'un sous-canal.A channel for a data processing system is provided with a time of day clock (12) which is synchronized with the time of day clock (14) of the associated central processor. Both the central processor and the channel processor record the times of particular events, and the channel uses these times to calculate two times called "function in progress" and "function active". Both times start when the central processor executes an instruction to start an input / output operation. The current function ends when the channel has completed an initial selection. This time presents the delays by the channel processor in programming the channel resources for the input / output operations. The active function ends at the end of the channel. A new instruction, "set channel monitor" (40), makes it possible to validate or invalidate these measurements. An information block (SCHIB) for each subchannel defines one or more measurement modes for a subchannel or invalidates the measurement of a subchannel.

Description

METHOD AND APPARATUS FOR MEASUREMENTS OF CHANNEL OPERATION
Field of the Invention
This invention relates to a method and apparatus for measuring the time that is taken by components of a data processing system for channel operations.
Introduction
A central processor includes a main store and a computing engine or engines that execute system programs and user programs that are located in main store. A channel includes a channel store and a channel processor that handles I/O (input/output) operations of peripheral devices. The channel processor executes an I/O program that is located in main store and is made up of commands. To begin an I/O operation in response to a request by a user program or a system program, the system control program executes I/O instructions. For example, an I/O instruction and the associated protocol to start an I/O operation identifies a particular I/O device, a Location in main store when the channel program is located, and a Location in main store where the channel is to save or fetch data. In the data processing system that will be described later, the channel processor also performs operations relating to scheduling the I/O devices to handle particular tasks as the devices and associated data paths become available.
A general object of the invention is to provide a new and improved method and apparatus for measuring the time that is required for channel operations. The Prior Art
There are many useful applications for monitoring or measuring operations in a data processing system. As a familiar example, the time that a user of a system is connected to the central processor or other resources of the system commonly appears at the end of a print out. This information is useful in billing the user. It is also known to measure operations of many different system components so that operating personnel -can tell whether these components are being used effectively or in order to measure the operation of a program that these components execute. This information can be used to plan for expanding the system as components become overloaded or to reconfigure the system to better balance the use of the components. Measurement data can also be used dynamically to schedule tasks to be performed on particular components that happen to be less heavily used and to avoid data paths that are more heavily used.
A number of techniques have been suggested for making these measurements and some of these techniques are adapted to the method and apparatus of this invention. As a starting example that is not specifically relevant to this invention, it is conventional in a development laboratory and also in systems that have been installed at a users location to attach temporary probes to signal points or similarly to make permanent connections to lines that carry signals for operations that are to be monitored. Pulses on these lines can be counted or they can be used to start and stop timers.
c:.PI As a more relevant example, processor and channel functions have been measured by programs that run on the central processor. The processor has a time δf day clock and the measurement program accesses the time of day clock and keeps track of the starting times and the accumulated times for selected operations that can be signaled to the monitoring program. See "OS/VS2 MVS Resource Management Faclity (RMF) General Information Manual GC28-0921-2", available from International Business Machines Corporation.
Several other references relate to the general technique of monitoring an operation by means of special instructions that are located in the program that performs the operation. These instructions start a timer at a particular point in a program that is to be timed and stop the timer at a later point. Similarly, a counter can be incremented by instructions that are made part of a routine for an operation that is to be counted. See IBM Technical Disclosure Bulletin, April, 1968, pages 1700-1703, Freeman,
U. S. Patent 3,763,474, Taylor, ϋ. S. Patent 3,399,298, Denny, U. S. Patent 4,034,353.
Summary of the Invention
The method and apparatus of this invention are particularly adapted to perform measurements on a channel operation that is started by a machine language instruction called Start Subchannel. In this operation, the instruction and the associated protocol identify to the channel a subchannel and an associated I/O device and the main storage location of the channel program. This information is passed to the channel, and the channel then schedules the I/O operation in the same general way that the operation would otherwise be scheduled and dispatched by a control program in the central processor, and initial selection then takes place. One of the objects of this invention is to measure the delays between the execution of Start Subchannel in the central processor and Initial Selection which later takes place independently in the channel. For this measuring operation, the invention includes a time of day clock that is synchronized with the time of day clock of the central processor. Means is provided in the I/O Supervisor program of the operating system of the central processor to read the time of day clock of the central processor and to store this value in a suitable location that is accessible to the channel. Means is provided in the channel program that performs initial selection to read the time of day clock of the channel and to fetch the value of the time of day clock that was stored by the central processor and to calculate the time difference and to store this difference in a suitable location. This time is called Function Pending Time. After Initial Selection the device typically disconnects from the channel and later reconnects and continues, typically with further disconnects, until the channel interrupts the central processor to signal that the operation has been completed. This point in the channel operation is called Channel End (because the channel sets a status bit that is called Channel End) . The accumulation of times during which the device is connected is called device connect time. In the system of this invention the channel provides the device connect time in one form that is suitable for use such as billing the individual user of the subchannel and it accumulates this time in a second form that is suitable for use in manually or automatically planning or scheduling channel resources.
The invention also provides means in the channel program for measuring the time between Start Subchannel and Channel End which is called Function Active Time. These measurements are useful directly and they can be used in combination to calculate other useful functions.
The channel has means in the routine for handling ending status to store Function Pending Time, Function Active Time and Device Connect Time in a Subchannel Measurement Block location in main store that is preassigned to the particular subchannel. (Device
Connect Time is also stored separately in a Subchannel Status Word.)
The invention also provides means including a new machine language instruction called Set Channel Monitor (SCHM) for enabling the monitor function. This instruction contains the starting address of the subchannel measurement blocks which the channel uses for storing the monitored time values. The channel has means for storing this address. When this address is all zeros (or any predetermined value that is never used as the starting address) , the channel does not measure channel operations.
Means is also provided for selectively enabling or disabling the measurement function for each subchannel (when the measurement function is enabled by the Set Channel Monitor Instruction) . A data block for each subchannel that is called the Subchannel Information Block contains a two bit field that identifies one of three modes of monitoring operations. (One of the four possible codes is not used.) In one mode, the monitor function is disabled for the subchannel. In another mode only conventional device connect time is measured and is stored in the Sxibchannel Status Word. In another mode all of the subchannel measurements that have been described are collected and stored.
The Subchannel Information Block is also arranged to store an address offset or displacement to the starting address in the instruction Set Channel Monitor the channel program has means for adding the offset to the starting address for accessing the Subchannel Measurement Block.
Other objects and features of the invention will be apparent from the description of the preferred embodiment.
The Drawing
Fig. 1 is a timing diagram of an I/O operation showing points at which times are recorded and the time intervals that are measured.
Fig. 2 shows the-, circuit of a clock that is used by the channel in recording times.
Figs. 3A-D show components of the channel and the interconnecting signals in a representative measurement operation.
Fig. 4 is a diagram showing the format in storage of the channel measurement parameters and the associated system of addresses to these storage locations.
The Preferred Embodiment
The Operations to be Measured—Fig. 1
The invention is preferably adapted to be used with a system in which a central processor (which may have several engines) operates with a single channel (which also may have several engines) and in which each device has a separate subchannel (as is conventional) . In this system, the processor starts an I/O operation by means of an instruction that is called Start Subchannel. In the execution of this instruction. the channel is given the identification of the device and the address of the channel program in main store (both steps are conventional) . The central processor is then free to branch to some independent operation. Fig. 1 shows Start Subchannel as one of the measurement points in the system of this invention.
The information in the instruction Start Subchannel is put onto a queue in channel storage (sometimes called bump storage) and the channel schedules the resources that are required to establish the data path of the subchannel in the same general way that other tasks are scheduled by a processor. At a point in this operation the channel contacts the device controller in a conventional process that is called initial selection. Fig. 1 shows this point called successful initial selection. The time from Start Subchannel to Successful initia.1 selection is called Function Pending time.
Function Pending Time is useful because it may be long for some devices that are heavily used and shorter for other devices that are less heavily used. For example, a number of disks or other similar may provide a pool of storage space that the system control program allocates temporarily to programs of users. This measurement is useful in allocating storage space from devices that currently have shorter times for function pending.
When successful initial selection has been made, the channel executes the first command. In the example of the operation of a magnetic disk, this command tells the disk controller to position the disk head at a particular track for a read or write operation. This mechanical operation is relatively slow, and the device controller is ordinarily programmed to disconnect from' the channel for this operation. This point in Fig. 1 is indicated by the legend Disconnect. When the device is ready to execute a command of the channel program, it reconnects. Typically a device disconnects and reconnects several times after Start Subchannel and
Fig. 1 shows two representative Device Connect times. Device connect time is commonly measured for each user. As will be explained later, the system of the drawing provides this function on a user basis and also provides accumulated connect time for an individual device.
Fig. 1 also shows Channel End and Device End which are conventional points in an I/O operation. The time from Start Subchannel to Channel End is measured by the apparatus of this invention and is called Function Active time. Function Pending, Function active and
Device connect times are each useful individually, and in addition they can be combined to calculate other times.
The Channel Clock—Fig. 2
The channel is provided with a clock 12 that is used in the measurement operations of this invention. The clock conventionally comprises a number of counter stages that are connected to be incremented by a stepping or advance pulse that appears periodically on a line 13 at intervals that correspond to the resolution that is desired in the channel measurements.
The channel clock is synchronized with the time of day clock 14 of the associated processor. The system time of day clock can be read by an instruction called Store Clock (STCK) which includes an address of a sixty-four bit location in main store where the current value of the time of day clock is to be stored. See "IBM System/370 Principles of Operation: GA22-7000, pages 141, 142. This clock also has a number of counter stages and an oscillator 15 that steps the counter in increments that represent units of time. One stage of the counter is selected as appropriate to the degree of resolution that is desired in the channel measurements, and in the preferred system this interval is one hundred twenty-four microseconds. Line 13 connects the one hundred twenty-four microsecond output of the system time of day clock to the advance input of the channel clock.
Another time signal of the system time of day clock is connected by a line 17 to form a reset for the channel clock. This time unit is eight seconds in the preferred system. This reset from the system time of day clock keeps the channel clock identical to the corresponding stages of the -system time of day clock (after an initial reset operation) so that an operation can be timed partly from the system time of day clock and partly from the channel clock. This reset connection
c-:.:π also synchronizes the clocks of different channels that are part of a multi-processor system because the time of day clocks of the different processor systems are independently synchronized. (There is one channel for each processor system and a processor system has one or more processors (not shown) that operate under a common control program.
Eight seconds is conveniently represented by a sixteen bit value and it is long enough to include virtually any possible I/O operation that is to be measured.
The channel clock is arranged to be read by an instruction or a micro-instruction of the channel processor and the clock value is stored in the channel store at a location that is specified in the instruction. This structure is similar to the structure of the system time of day clock and is illustrated in Fig. 2 by a signal Store Clock on a line 18, the channel store 20 and a system of gates 21 that transfers the channel clock value to a channel store location designated by an address on a line 22 from the instruction decoder.
The Device Connect Measurement—Figs. 3A to 3D
This series of figures shows the components of the channel that measure Device Connect time, which is a convenient example of all of the measurement operations. The operations of the channel store 20,
OMPI the control store 25 and the arithmetic and logic unit (ALU) 26 will be familiar from standard operations of these components.
In Fig. 3A, initial selection has been made and is signaled by a device on a tag line 30 called Service In. This signal causes the channel to execute a microprogram that is located in control store 25. This otherwise conventional microprogram includes instruction means for reading the channel clock 12 and loading its current value into a predetermined location 33, arbitrarily called Start Time, in channel store 20. The address of this storage location and a field calling for a store operation are carried in the microcode instructions as is conventional and as line 35 in the drawing represents. The microcode also supplies the signal Store Clock on line 18.
Thus, at an appropriate point in the usual routine associated with device reconnect, the channel time is stored. Since the speed of the channel processor is very fast in relation to the resolution of the channel clock, it will ordinarily make little difference where this measurement operation is located in the routine for handling Service In.
The fall of Service In conventionally signals device disconnect and causes the channel to begin a routine to respond to this condition. In the method and apparatus of Figs. 3B, C and D, this conventional routine contains microinstruction means for reading the channel clock. subtracting the value from the value stored in Fig. 3A, and storing the difference in a predetermined location of channel store that is called Accumulate. The drawing is representative of various ways in which this operation can be performed.
In the step illustrated by Fig. 3B, a microinstructio or a series of microinstructions read the channel clock and apply the clock value at one input of ALU 26 and also fetch from channel store 20 the clock value stored in the dperation of Fig. 3A and apply this value to the other input of ALU 26 and also control ALU 26 to perform a subtraction and to load the difference into a register 38 or an equivalant location in channel store 20.
Fig. 3C is a continuation of this operation, as the signal Next Step to the control store signifies. In this operation the channel store is accessed at the location Accumulate which holds the accumulated time for any previous connect/disconnect sequence. This value and the difference in register 38 are summed and stored in a location 39. As the operation of the channel continues in Fig. 3D, the sum in register 39 is stored in the accumulator location in channel store. As the device continues to reconnect and disconnect, the operations of Fig. 3A through 3D are repeated and the device connect time accumulates in the Accumulate location.
Notice that the channel clock may be reset between the step of Fig. 3A and the step of Fig. 3B so that the difference in register 38 is a negative value. In this situation, the reset value of the channel clock (eight seconds in the specific example) is added to the negative value. The conventional techniques for testing for a negative value and either adding or not adding the eight seconds will be readily understood without a specific example.
The Other Channel Measurement Operations
From the detailed example of the operation for device reconnect and device disconnect, the method and apparatus for the measurements at the other points in Fig. 1 can be understood from only a brief description. Start Subchannel time is recorded by the central processor by conventional instructions in the routine that executes Start Subchannel. The time of day clock can be stored in any convenient location that is accessible to the central processor and to the channel, such as a location in main store that is otherwise assigned to the operating system or to a location in channel store. This operation of the central processor can be thought*of as a counterpart of the operation shown in Fig. 3A. (Note that this routine is performed only by the control program of the central processor and not by user programs.) Successful initial selection is signaled by the rise of Service In, and the related channel routine includes means for reading the channel clock and subtracting from it the time of Start Subchannel in the way that has been described for any device connect time in relation to Figs. 3B, C and D.
Channel End is signaled to the channel by the device and in response to this signal the channel reads the channel clock and calculates Function Active time in the way that has been described for Function Pending time. The channel also updates the device connect time as already described.
Storage Organization—Fig. 4
Subchannel measurement operations take place when the central processor executes an I/O instruction called Set Channel Monitor (SCHM) . As block 40 in Fig. 4 shows, the instruction has the familiar format of a sixteen bit field for the operation code and a sixteen bit field for an address in the form of a base B2 and a displacement D2. When the instruction is executed by the central processor, the channel stores the address as represented by block 41. This address (if it is not all zeros) points to a location in the central processor main store 43 where the measurement data is to be stored for each subchannel that is to be measured.
Fig. 4 shows the format for storing the measurement parameters. Each subchannel has four word locations (of thirty-two bits each) 45, 46, 47 and 48 for the measurement parameters. Each channel also has an extended measurement area of four additional words (not shown) for additional measurement parameters that may be desirable. When the measurement parameters have been loaded into main storage, they are accessible to a program such as RMF that would print them in a format
OMPI is useful in the operation and organization of the data processing system. The parameters can also be used by a program that allocates system resources' as has already been described.
In channel store 20 the channel maintains a block for each subchannel that is called the Subchannel Information Block (SCHIB) . This block includes an address offset that is combined with the address in register 41 to point to the measurement block for the particular subchannnel. Addressing of this kind is widely used and does not require detailed explanation. The SCHIB*s can be assigned to any convenient location in channel store 20.
The channel also maintains a Subchannel Status word (not shown) for each subchannel which contains for example the CCW Address and is generally similar to a Channel Status Word. Device connect time is also stored in this status word.
When the address field of the instruction Set Channel Monitor is set to all zeros, the measurement operation is inhibited. Thus the instruction can be thought of as having one form to enable measurement and a second form to disable measurement. In the channel hardware the measurement is enabled by a latch that is set by this address and. reset by the all zeros address or equivalently by a corresponding bit that is set in a control word of the channel engine. The microprogram routines that have been described in
C.a.-Pl relation to Fig. 4 include instructions to test this status and to execute the measurement instructions or to branch around them according to the condition established by Set Channel Monitor. In the operating system, routines that include Set Channel Monitor and associated routines that set up the SCHIB's are enabled or disabled for a particular measurement in the same way that the operating system is selectively controlled to provide or not to provide available functions.
Means is also provided for disabling an individual subchannel for measurement or for enabling one of two measurement modes. This condition for a subchannel is controlled by a two bit field in its SCHIB and this field is tested by the techniques described for Set Channel Monitor. In one mode, the subchannel is enabled for the measurements that are shown in main store 43 in Fig. 4 and for reporting device connect time in the Subchannel Status Word. In another mode, only the device connect time of the Subchannel Status Word is measured.
Storing The Measurement Parameters
As part of the normal operation of the channel at Channel End, the channel includes microprogram means to store device connect time, Function pending time, and Function Active time, (according to the mode set in the SCHIB and whether the channel is enabled for measurement) In addition the channel fetches, increments and restores the Sample Count and the SSCH chount shown in Fig. 4. SSCH count is incremented in either active measurement mode, whenever device connect time is stored. Sample Count is stored only when Function Active and Function Pending are also stored. The conditions of the microcode will be apparent without detailed explanation.
Other Embodiments
The hardware of the channel and the central processor correspond specifically to the IBM 3081 but the channel clock of this invention and its connection to the conventional processor clock is applicable to various processor and channel designs. This processor has a single channel, but the invention is applicable to systems that conceptually have more than one channel. Other aspects of the invention have been illustrated by the incorporation of new microcode routines in the otherwise normal microprograms of the channel. In some applications of the invention it may be desirable to start and/or stop the timings from tag lines that signal the occurence of the operation as is often done with monitors that separately attach to components of a data processing system. The actual microprograms can be implemented in various ways. Thus, those skilled in the art will recognize many applications for this invention and appropriate variations within the spirit of the invention and the scope of the claims.
OMPI

Claims

1. A channel measuring system comprising,
a central processor having a time of day clock, a channel having a channel clock, means connecting a stage of the central processor time of day clock to increment the channel clock at intervals defining the resolution of the measuring system, and means connecting a stage of the central processor time of day clock to reset the channel clock at intervals corresponding to the longest channel operation to be monitored, whereby after an initial reset operation the channel clock is comparable with corresponding stages of the central processor time of day clock,
means in the central processor for starting a channel operation•including means for storing the value of the system time of day clock in a predetermined location,
means in the channel for accessing the channel clock at a predetermined point in said channel operation, and
means in the channel for subtracting the stored value of the central processor time of day clock and the channel clock and calculating the time interval from the time when the central processor starts the channel operation to the time when the channel reaches the predetermined points in its operation. . whereby channel measurements operations are performed.
2. The system of Claim 1 wherein said central processor includes means for executing an instruction selectively enabling or disabling said channel measurement operations.
3. The system of Claim 2 wherein said channel includes means -for storing said time in a location in main store and said instruction includes a pointer to the address of this location.
4. The system of Claim 3 wherein said channel includes means responsive to a predetermined address in said instruction to disable said channel measurement operations.
5. The system of Claim 4 wherein said channel includes an information block for each subchannel, said central processor includes means for loading an address offset into an information block, and said channel includes means for storing measurement parameters for a subchannel in the location in main store defined in said instruction and said subchannel information block.
6.. The system of Claim 5 wherein the central processor includes means for loading into the subchannel information block a field defining a particular mode of measurement or disabling measurement for the subchannel, and wherein said channel includes means responsive to said mode for measuring parameters on the basis of a particular user of the system and/or the basis of a particular subchannel.
7. The system of Claim 6 wherein said means responsive to said mode includes means for storing parameters measured on the basis of a particular user as part of a subchannel status word.
8. The system of Claim 1 wherein said channel means for accessing said channel clock at a predetermined point includes means for accessing said channel clock at successful initial selection and at channel end and wherein said channel means for calculating the time interval includes means for calculating the time from starting the subchannel operation to successful initial selection (Function Pending Time) and the time from starting the subchannel operation to channel end (Function Active Time) .
CMPI
9." The system of Claim 8 wherein said channel means for accessing said channel clock at a predetermined point includes means for accessing the clock at device connect and device disconnect times and wherein said channel means for calculating the time interval includes means for calculating the interval between a device connect and the next device disconnect and for accumulating device connect time for a subchannel operation.
10. The system of Claim 9 wherein said channel includes means for storing device connect time in a first location (parameter measurement block) and a second location (subchannel status word) and wherein said central processor includes means for accessing said first location and calculating the usage of the associated subchannel without regard to particular user programs and for accessing the second location and calculating the use of I/O resources by a particular user program.
CMPI
11. A method for measuring parameters of subchannel operations, comprising,
recording the time of execution of a central processor instruction to start a subchannel operation (Start Subchannel) ,
determining the time of acceptance of the first channel command by the device associated with the subchannel (Successful Initial Selection) ,
determining the time of the completion of the channel operation (Channel End) ,
operating on the times to produce a first time (Function Pending) that indicates the delays by the channel in obtaining resources for the subchannel operation and to calculate a second time (Function Active) that indicates the total time of the subchannel operation.
EP19810903022 1981-10-13 1981-10-13 Method and apparatus for measurements of channel operation Withdrawn EP0090804A1 (en)

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Families Citing this family (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2197096B (en) * 1986-10-29 1990-08-01 Burroughs Corp Microcode monitor
US5778194A (en) * 1996-04-08 1998-07-07 Symbios, Inc. Method and apparatus for measuring performance of a computer bus
US6070206A (en) * 1997-03-31 2000-05-30 Lsi Logic Corporation Method and apparatus for terminating a bus
US6061806A (en) * 1997-05-12 2000-05-09 Lsi Logic Corporation Method and apparatus for maintaining automatic termination of a bus in the event of a host failure
US6029216A (en) * 1997-06-27 2000-02-22 Lsi Logic Corporation Auto-termination method and apparatus for use with either active high or active low terminators
US6092131A (en) * 1997-07-28 2000-07-18 Lsi Logic Corporation Method and apparatus for terminating a bus at a device interface
US8117614B2 (en) 2006-05-19 2012-02-14 International Business Machines Corporation Extract CPU time facility
GB2440216A (en) * 2006-05-19 2008-01-23 Ibm Computer program for calculating the (accumulated) processing time for tasks
US8504754B2 (en) 2010-06-23 2013-08-06 International Business Machines Corporation Identification of types of sources of adapter interruptions
US8639858B2 (en) 2010-06-23 2014-01-28 International Business Machines Corporation Resizing address spaces concurrent to accessing the address spaces
US8635430B2 (en) 2010-06-23 2014-01-21 International Business Machines Corporation Translation of input/output addresses to memory addresses
US8468284B2 (en) 2010-06-23 2013-06-18 International Business Machines Corporation Converting a message signaled interruption into an I/O adapter event notification to a guest operating system
US9195623B2 (en) 2010-06-23 2015-11-24 International Business Machines Corporation Multiple address spaces per adapter with address translation
US8621112B2 (en) 2010-06-23 2013-12-31 International Business Machines Corporation Discovery by operating system of information relating to adapter functions accessible to the operating system
US8510599B2 (en) 2010-06-23 2013-08-13 International Business Machines Corporation Managing processing associated with hardware events
US8549182B2 (en) 2010-06-23 2013-10-01 International Business Machines Corporation Store/store block instructions for communicating with adapters
US8572635B2 (en) 2010-06-23 2013-10-29 International Business Machines Corporation Converting a message signaled interruption into an I/O adapter event notification
US8615645B2 (en) 2010-06-23 2013-12-24 International Business Machines Corporation Controlling the selectively setting of operational parameters for an adapter
US9213661B2 (en) 2010-06-23 2015-12-15 International Business Machines Corporation Enable/disable adapters of a computing environment
US8566480B2 (en) 2010-06-23 2013-10-22 International Business Machines Corporation Load instruction for communicating with adapters
US9342352B2 (en) 2010-06-23 2016-05-17 International Business Machines Corporation Guest access to address spaces of adapter
US8505032B2 (en) 2010-06-23 2013-08-06 International Business Machines Corporation Operating system notification of actions to be taken responsive to adapter events
US8650337B2 (en) 2010-06-23 2014-02-11 International Business Machines Corporation Runtime determination of translation formats for adapter functions
US8650335B2 (en) * 2010-06-23 2014-02-11 International Business Machines Corporation Measurement facility for adapter functions
US8626970B2 (en) 2010-06-23 2014-01-07 International Business Machines Corporation Controlling access by a configuration to an adapter function
US8478922B2 (en) 2010-06-23 2013-07-02 International Business Machines Corporation Controlling a rate at which adapter interruption requests are processed

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3540003A (en) * 1968-06-10 1970-11-10 Ibm Computer monitoring system
US3588837A (en) * 1968-12-30 1971-06-28 Comcet Inc Systems activity monitor
US3763474A (en) * 1971-12-09 1973-10-02 Bell Telephone Labor Inc Program activated computer diagnostic system
US3771144A (en) * 1972-07-24 1973-11-06 Ibm Clock for computer performance measurements
US3748650A (en) * 1972-08-21 1973-07-24 Ibm Input/output hardware trace monitor
US3818458A (en) * 1972-11-08 1974-06-18 Comress Method and apparatus for monitoring a general purpose digital computer
US3906454A (en) * 1973-05-18 1975-09-16 Bell Telephone Labor Inc Computer monitoring system
US4034353A (en) * 1975-09-15 1977-07-05 Burroughs Corporation Computer system performance indicator
US4126895A (en) * 1975-12-29 1978-11-21 International Standard Electric Corporation Data processing system with monitoring and regulation of processor free time
US4166290A (en) * 1978-05-10 1979-08-28 Tesdata Systems Corporation Computer monitoring system

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8301524A1 *

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