FR2460007A1 - Computer data capture and real time logic analysis system - uses plug-in unit with probe to receive data for error analysis using multiplexer circuit and fifo store - Google Patents

Abstract

The real time logic analyser is used to capture and analyse information generated within a computer system in order to identify hardware and software errors. Information times from the computer are monitored by a probe that is coupled over an interface to a multiplexer. The multiplexer output is entered into a first-in first-out memory with a coupled code detector. Selector units execute the necessary tests on the captured data to identify errors. The system modules are operated in a synchronous mode with signals from a central control stage.

Description

 The invention relates to a device for entering and pre-processing information for monitoring digital computers, in particular real-time control computers for large computer systems, the information entered and pre-processed being intended in particular to optimize the monitored computer or the associated system or to discover the precise origin of faults attributable either to the hardware (hardware) of the computer, or to software (software). The device of the invention is advantageously usable for the monitoring of control computers and management of electronic automatic exchanges of telecommunications networks.

 The device of the invention is of the so-called "hardware monitor or" logic analyzer "type, that is to say that instead of being supported by the monitored computer by modifying the characteristics and in particular the performance (case of 'a software monitor "), it is designed to be connected to this computer while remaining" invisible ", that is to say allowing it to continue operating without changing its environment.

 Hardware monitors of the known type, intended in principle to facilitate the choice and optimization of a computer system configuration, generally only allow quantitative and statistical analysis of the flow of information circulating in the computer, but do not allow to explain the content. Consequently, "rare", that is to say infrequent, defects go unnoticed as well as the consequences of these defects by propagation and contamination. However, if it is generally possible to mitigate these consequences in computers fitted with data centers, this possibility does not exist when it comes to control computers, a "rare" defect which could be the cause of incidents serious and irreversible operation of the controlled system.

Logic analyzers of the known type, intended in principle to facilitate the development of programs, generally do not allow
- to observe the same source for a long time, the duration of observation being limited by the storage capacity,
- to use the information collected by several subsystems operating simultaneously,
- to observe several asynchronous sources operating in parallel,
On the other hand, the device of the invention makes it possible in particular to record and store, without disturbing the operation of the monitored computer:
- arrival times of interruptions,
- the levels of these interruptions and the associated contexts;
- the sequence of orders executed or associated information,
- the orders given to the connection units and the responses thereof, as well as the readings and writes in central memory, which makes it possible to know the data on which the programs operated and the data which resulted therefrom,
- exchanges with other computers, in particular if there is traffic sharing,
- etc., etc.......

 More generally, the device of the invention allows a diachronic and synchronous study of the execution of programs by the monitored computer and in particular the obtaining of presentations of successive states of this computer, presentations all the more summarized as the corresponding states are older.

 The device of the invention, intended to be connected via a sampling probe to accesses of specific organs of the computer to be monitored to enter information transmitted by the probe and to develop data signals from the information entered is essentially characterized in that it comprises a multiplexing device which restores the information entered in the form of a series of messages each of which is composed of a word characterizing a data content and an indicator characterizing the nature of this data.

Advantageously, the device of the invention further comprises
an input memory connected to the output of the multiplexing member, means of admitting into this memory a determined sequence of messages and means of controlling the delivery of the content of this memory to a determined output of the device,
a message processing and selection chain comprising on the one hand a first queue (FIFO) whose input is connected at the output of the multiplexing member, on the other hand a message selection unit comprising a message sorter receiving the content of this first queue and selecting the messages carrying determined indicators and a second queue storing the messages selected by the sorter, finally, means for delivering to the sorter selection instructions characterizing message indicators to be selected and means for controlling the delivery of the contents of the queues to determined outputs of the device,
a message display unit comprising, on the one hand, a display screen and, on the other hand, means for displaying on this screen the content of message data of the multiplexing unit carrying determined indicators.

 Advantageously also, the message processing and selection chain of the device of the invention further comprises at least a second message selection unit inserted after the message selection unit already considered and comprising a second sorter of messages and a third queue, the input of which is connected to the output of this sorter, means of delivering to this second sorter selection instructions characterizing indicators of messages to be selected and means of controlling the delivery of the content of this third waiting wire at a specific exit from the device.

 In general, other selection units can be added to the chain according to the observations that one wishes to make.

The constitution of the device of the invention, its operation and its advantages appear in a more detailed manner in the description of the nonlimiting exemplary embodiment which follows and which refers to the appended drawings which are all block diagrams and in which
FIG. 1 is a general diagram of this exemplary embodiment,
FIG. 2 is a diagram of the multiplexing member,
FIG. 3 is a diagram of 11 one of the queues,
FIG. 4 is a diagram of a code detector,
- Figure 5 is a diagram of the display unit.

These different figures in principle only contain the elements necessary for understanding the operation of the corresponding diagrams. Unless exception, the following provisions are not represented
- links carrying synchronization or internal clock pulses, information availability or acknowledgment signals and reset pulses, etc ...

 - amplifiers, inverters, etc ...

 - interfaces.

We first consider Figure 1. The multiplexing and labeling device 200 has a plurality of inputs which are connected to judiciously chosen points of the computer to be monitored (not shown) by means of a probe 001 and an interface
INBC (standardized connection interface).

 The probe 001 does not belong to the monitoring device of the invention. It is specific to the monitored computer and can be incorporated into it at least in part. Its role is to ensure the connection of the inputs of the monitoring device to the selected points (to which it is possibly connected via a repeater) of said computer, while making the device "invisible" to said computer. Its structure therefore depends on its structure. If all the functional blocks of the monitored computer are linked together by links such as cables or buses, it is at these links that most of the probe collection points can be connected. access to the computer blocks is provided by a backplane (for example access between the control unit and the logic of the memory unit), it is at the very heart of one of these blocks ( for example the logic of the memory unit) that the possibly associated collection points will be broadcast.

 The INBC interface consists of three pluralities of bus or connecting wires 201, 202 and 205. The wires or bus 201 are called "information wires. They are connected, via the probe 001, to the points of the monitored computer capable of supplying quantitative information or data relating in particular to the content of the central memory. This information can be partially multiplexed in order to reduce the number of buses or wires. The wires 202 are said to be "event wires". They are connected by the probe 001 to the points of the monitored computer capable of providing qualitative information characterizing the nature of the quantitative information transmitted by the wires or buses 201. This qualitative information is for example a progression of the ordinal counter, the arrival of a interrupt instruction, change of context, etc. The wires 205 are associated with the marking of isolated or independent events including sampling by means of the wires 201 is not necessary.

 The wires or buses 201, 202 and 205 attack the inputs of the multiplexing member 200, an embodiment of which will be given below with reference to FIG. 2. This member is controlled, as are the members or chains which it supplies, by a control and operating unit 100 advantageously equipped with a minicomputer. The required control link is marked 203.

Organ 200, according to the instructions issued by this link
a) selects information from that transmitted by the links 201, 202 and 205,
b) restores the selected information in the form of a series of messages which each include a word which contains either at least quantitative information (that is to say a data content) conveyed by a wire 201 and an indicator ( flag) which characterizes the nature of this data and which is deduced for example from the rank of the event wire 202 carrying the corresponding qualitative information - either qualitative information deduced from the signal conveyed by a wire 205 and from the corresponding indicator,
c) ensures the synchronization of the other organs or of the chains which it supplies.

 Each message thus contains not only a data content but also the indications making it possible to classify this data content according to its location in the monitored computer or near the phase of the program which is its origin.

 The messages of the organ 200 are delivered, via links 204, to an input memory unit, to a selection and processing chain and to a display unit.

 The input memory unit 300 is positioned in read and write mode by the unit 100 by means of links 301 and records the data which it receives from links 204 by its inputs 302. It comprises, associated with registers of write, read and control, an input memory whose organization is preferably similar to that of the central memory of the monitored computer but whose capacity is in principle more reduced. It makes it possible, at times determined by an operator or by the unit 100 computer program, to take "photographs" of the content of part of said central memory. The information which it restores is delivered on command. , either directly to a mass memory (not shown), or to the control unit 100 which transmits them, after possible processing, to a recording or display member such as a mass memory 110 or a printer 120. However, the unit 100 can still retransmit this information to a data processing center via links 130.

The message selection and recording chain also connected at the output of the multiplexing member 200 via the links 204 comprises, in the example represented by FIG. 1, the following members
a first queue 400 (FIFO) acting under the control of the unit 100 (links 401) to record and restore (links 402) to a member next to the chain the sequence of messages delivered by the multiplexing member 200; (here we mean by "queue" any memory organ restoring in their chronological order of writing the information that it has temporarily stored);
- a code detector 800 connected at the output of the queue 400 and controlled by the unit 100 by means of links 801; the description of this organ is not necessary to understand how the scheme works; it is therefore postponed further;
a first message selection unit 500 connected at the output of the code detector 800 and comprising a first sorter 510 which receives the sequence of messages retransmitted by this code detector and a second queue 550 connected at the output of this first sorter ;
- a folder 600 connected at the output of the queue 550;
a second message selection unit 700 which includes a second sorter 710 receiving the sequence retransmitted by the folder 600 and a third queue 750 connected at the output of this sorter;
The first sorter 510 selects some of the messages to form a second smaller sequence delivered to the queue 550. The selection is made according to the message indicators according to the instructions that the unit 100 addresses to this sorter by links 501. The queue 550 restores this second sequence by links 502 in accordance with the orders that the unit 100 delivers by links 503.

 The folding device 600 is only useful when the length of the words admitted by the following organ or unit (here the selection unit 700) is shorter than the length of the words delivered by the preceding organ or unit (here the selection unit 500). It receives a control word from the unit 100 via links 601, compares with this control word the indicators of the messages it receives and, if the comparison is positive, generates two messages by forming two shorter data words and by associating them respectively with two new indicators. If necessary, such a folder can be inserted either between the multiplexing unit 200 and the sequential memory 400, or between the memory 400 and the sorter 510, or even in another location of the chain.

 The second sorter 710 selects the messages of the second sequence retransmitted by the folder 600 (or the queue 550) to form a third smaller sequence addressed to the queue 750. The selection is made according to the indicators of messages received, according to the selection instructions that the unit 100 delivers by links 701. The queue 750 receives this third sequence and restores it by links 702 to the unit 100 on the order that the latter ci delivers by links 703.

 We will give further information on the constitution and operation of queues 400, 550 and 750. We can already note that their combination with sorters 510 and 710 allows them to store "states" of the monitored computer which are all the more succinct as they are older.

 The number of selection units may vary according to the characteristics of the computer monitored and the tasks that are imposed on the monitoring device. In some use cases, a single selection unit may suffice. In other cases, it may be useful to add one or more selection units to the diagram in Figure 1. It is therefore advantageous to give these selection units a modular configuration so that the necessary adaptations can be quickly made.

 There will be described later, with reference to FIG. 5, an exemplary embodiment of the display unit 900 controlled by the control unit 100 by means of links 901 for displaying the messages delivered by multiplexing member 200.

 We now consider FIG. 2 relating, as already indicated, to the electrical diagram of the multiplexing member 200 of FIG. 1. A multiplexer 210 collects the signals conveyed by the links 201 (wires or bus of information) or 205 (after formatting), selects them and routes them via the output links 211 in the form of a succession of data words. If for example the links 201 and 205 comprise n bus and if the serial words routed each have 36 bits (32 data bits and 4 parity bits), the capacity of the multiplexer 201 must be at least 36.n bits.

 The multiplexer 201 in fact produces, from n serial words (each of 36 bits) delivered in parallel to its inputs, a parallel word of 36 bits.

 The signals of the event wires 202 (for example 32 wires eo to e31) pass through an event memory 220, through an event register 221 which restores them in synchronism with the clock signals H (the clock required not shown) and by a priority encoder controlled by the unit 100 by means of links 203a belonging to the group of links 203 in FIG. 1.

The priority encoder 222 makes it possible to modify the priority levels assigned to events (for example to adapt the device of the invention to the monitoring of a new computer) and to inhibit certain events if necessary. This coder # delivers the event signals by links 223 to two correspondence tables constituted by PROM memories 231 and 232. The memory 231 generates selection orders which it delivers to the control input of the multiplexer 210 by links 212. The memory 232 delivers by links 213 indicators intended to be added to the data words delivered by the multiplexer 210 to form the messages to be conveyed to the input memory 300, to the queue 400 and to the display unit 900 (fig. 1) or to a triggering system. These are the links 205 which make it possible to incorporate into the data words delivered by the multiplexer 210 bits signaling "independent" events.

These independent events ei can be for example the commissioning of a new module, the substitution of another computer for the monitored computer, etc. They are shaped by a set of circuits 240 with doors and flip-flops (adding in addition, if necessary, time signals) and transmitted to corresponding inputs of the multiplexer 210 by links 242.

 Finally the links 211 (output of the multiplexer 210) which convey the data words and the links 213 (output of the correspondence table 232) which convey the corresponding indicators are connected to the inputs of four registers 241, 242, 243 and 244 which carry out the conjunction of these words and these indicators to form the messages. The transmission of output messages from these registers can be authorized or prohibited by ET 245 gates controlled by links 203b belonging to the group of links 203 (fig. 1) for multiplex control from the control and operating unit. 100.

 The messages delivered by the register 241 are transmitted to the unit 100 by links 246 and are taken into account by this unit to actuate in particular the various doors 245 in order to ensure the triggering functions. The messages delivered by the register 242 are intended for the entry memory 300 (fig. 1), the messages delivered by the register 243 are intended for the sequential memory 400 and the messages delivered by the register 244 are intended for the unit of viewing 900.

 The input memory unit 300 (fig. 1) does not require any particular description. It can however be indicated that it includes a random access memory, the associated registers (write addressing, read addressing, write information, read information) and a control logic for these different registers translating the instructions that the unit of command and operation 100 routes via the links 301. The information restored by the RAM via the information register read can be, as shown in FIG. 1, delivered to the unit 100 by the connections 383 and recorded by the mass memory 110 or by the printer 120, but it may be advantageous, to lighten the task of the unit 100, to deliver them directly to a mass memory not shown in FIG. 1. It is obviously necessary that the input memory is, like the multiplexing unit 200, at least as fast as the central memory of the monitored computer.

 We now consider Figure 3 which shows an embodiment of a queue of the "tracking" chain (400, 500 or 700, fig.1) advantageous in that it comprises means for this memory regulates itself, that is, so that it pours its contents to the next device (code detector 800, sorter 710 or even control unit 100) as soon as it reaches a filling rate determined by the control unit.

By way of example, FIG. 3 shows the diagram of the queue 550. The memory organ thereof is for example a memory
RAM 560 type MOS. It is this RAM memory which receives the messages selected by the detector 800 and restores them in good time to the folder 600. A logic of memory unit LUM 570 triggers respectively by links 571 and 572 the advancement of the counter 573 CAE ( write address counter) and counter 574 CAE (read address counter) and receives respectively by links 575 and 576 content signals from these counters.

These control the addressing of the memory 560 by means of the multiplexer 580 to which they are connected by links 577 and 578 and of the register 581. The filling level of the memory 560 triggering the discharge of the oldest content word in the latter towards the folding machine 600 is fixed by the control and operating unit 100 (FIG. 1) via links 503a belonging to the group of links 503 and a command word generator 590. When the logic 570 finds that the filling level of the memory 560 corresponds to the level fixed by this control word, it informs the unit 100 by the link 579.

There is no need to describe. in detail the logic of memory unit 570, the realization of which is within the reach of the specialist knowing the functions to be exercised.

 It will be recalled that FIG. 1 shows a code detector 800 inserted between the queue 400 and the selection unit 500 and controlled by the unit 100 via links 801. It detects the binary operation code of each word delivered by the multiplexer and modifies, if necessary, the associated indicator in order to allow subsequent application of a specific processing to the words designated by the same indicator. FIG. 4 shows a brief diagram of this code detector which includes a buffer register 810, a multiplexer 820, a data comparator 830 and an indicator modification circuit 840. The signals delivered by the queue 400 (data and indicators) are admitted to the inputs 821 of the multiplexer 820 via the buffer register 810, which also delivers them to first inputs 831 of the comparator 830 which also receives, by second inputs 832, criteria signals modifiers, delivered by the control unit 100 via the links 801. The comparator 830 uses the signals present at its inputs 831 and 832 to develop control signals for the indicator modification circuit 840 The signals from the latter are delivered to control inputs 822 of the multiplexer 820 in order to consequently modify the message indicators which appear at its inputs 821 and which it retransmits towards the unit of selection 500.

 Finally, consider FIG. 5 relating to an advantageous embodiment of the display unit 900 (FIG. 1). The messages routed by the links 204 are admitted to the first inputs 911 of the comparator 910 and to the inputs 921 and 926 of two buffer registers 920 and 925. The second inputs 912 of the comparator 910 receive command words delivered by the control unit 100 via links 901. Comparator 910 has three outputs. The two outputs 913 and 914 are respectively connected to the control inputs 922 and 927 of the two registers 920 and 925. The output 915 supplies, via an amplifier not shown, the brightness control electrode (Wehnelt) 933 a cathode ray tube 930. The signals retransmitted by the registers 920 and 925 are respectively transformed, by means of digital-analog converters 940 and 945, into direct voltages applied respectively to the two pairs of deflection electrodes 931 and 932 of the tube 930 Using the appropriate internal wiring, the comparator 910 can in particular validate the display on the tube screen. 930 signals corresponding to messages identified by specific indicators. For example, it controls the deflection of the spot by two components extracted from each indicator and its brightness by the data content of the corresponding message.

 It will be noted, to end this description, that the control and operating unit 100 performs several functions which are in particular the actual control of different organs of the device, as well as the management of the mass memory 110, of the memory input 300 and the trigger system constituted by doors 245 and the associated registers. We can therefore choose either to divide the unit 100 into a certain number of boxes each assigned to one or more specific functions, or to constitute it by means of a single microcomputer provided with the necessary interfaces. Another solution consists in eliminating the unit 100 and in providing each of the organs such as the multiplexer 20t, the queue 400, the selection units 500 and 700, etc. with command and control means allowing their autonomous operation.

Claims (11)

 1.- Device for entering and pre-processing information intended to be connected, by means of a sampling probe, to determined accesses of a computer to be monitored in order to enter information transmitted by the probe and for develop data signals from the information entered, characterized in that it comprises a multiplexing device which restores the information entered in the form of a series of messages each of which consists of a word characterizing a data content and an indicator characterizing the nature of this data.  2.- Device according to claim 1, characterized in that the multiplexing member comprises a multiplexer whose inputs are to be connected, via the probe, to a plurality of accesses of the monitored computer capable of providing information quantitative, said multiplexer delivering data content words, memory means the inputs of which are to be connected, via the probe, to a plurality of accesses of the monitored computer capable of providing qualitative information characterizing the nature of the quantitative information delivered to the inputs of the multiplexer, a first correspondence table elaborating, from the qualitative information retransmitted by said memory means, control signals of the eur multiplex, a second correspondence table elaborating indicators from said qualitative information and ways to add flags to data content words to form messages es.  3.- Device according to claim 1 or claim 2, characterized in that it comprises an input memory connected at the output of the multiplexing member, means for admitting into this memory a determined series of messages and means for controlling the delivery of the content of this memory to a determined output of the device.  4.- Device according to any one of claims 1 to 3, characterized in that it comprises a chain of processing and selection of messages comprising on the one hand a first queue whose input is connected to output of the multiplexing unit, on the other hand a first message selection unit comprising a message sorter receiving the content of this first queue and selecting the messages carrying determined indicators and a second queue storing the messages selected by this sorter, finally means for delivering to this sorter selection instructions characterizing indicators of messages to be selected and means for controlling the delivery of the contents of the queues to determined outputs of the device.  5.- Device according to claim 4, characterized in that the message processing and selection chain further comprises on the one hand at least a second message selection unit inserted after the first message selection unit and comprising a second message sorter and a third queue storing the messages selected by this sorter and on the other hand means for controlling the delivery of the contents of the second queue to the second sorter, means for delivering to this second sorter of selection instructions characterizing indicators of messages to be selected and means of controlling the delivery of the content of the third queue to a determined output of the device.  6.- Device according to claim 4 or claim 5, characterized in that the means for controlling the delivery of the content of at least one queue are means for controlling the reading of at least one word from this queue when it reaches a certain filling level.  7.- Device according to any one of claims 4 to 6, characterized in that the message processing and selection chain further comprises at least one folder.  8.- Device according to any one of claims 4 to 7, characterized in that the message processing and selection chain further comprises a code detector inserted at a determined location of said chain to modify the message indicators.  9.- Device according to any one of claims 1 to 8, characterized in that it comprises a message display unit connected at the output of the multiplexing member.  10.- Device according to claim 9, characterized in that said message display unit comprises a cathode ray tube and means for controlling the deflection of the spot of this tube by the word data content and by the indicator of each message .  11.- Device according to claim 10, characterized in that it further comprises means for controlling the brightness of the spot by a command word associated with each message.