KR20010008922A - Device and method of remote memory access channel for network virtual memory - Google Patents

Abstract

PURPOSE: A remote memory access channel(RMAC) device for a network virtual memory is provided to back up stored data in a memory of a presently-unused remote workstation when a used physical memory page is reallocated by a hard disk because of physical memory shortage, so as to make the hard disk read the stored data from the memory of the remote workstation without loading the data in the hard disk, to improve an input/output capacity. CONSTITUTION: A remote memory access channel(RMAC) client(1) snaps a 'II_rw_page()' function which is a disk memory system interface, and cashes a memory page in a remote memory. An RMAC supplies the remote memory to other workstation as a server in an RMAC server(2). An RMAC register(3) regularly maintains an RMAC list. A stored RMAC list(4) is operated and maintained by the RMAC client(1). A storing RMAC list(5) is operated and maintained by the RMAC server(2). An RMAC list is operated and maintained by the RMAC register(3).

Description

Device and method of remote memory access channel for network virtual memory

TECHNICAL FIELD The present invention relates to the field of distributed operating system software, and in particular, a remote memory access channel that can be used by NOW as if any workstation is its own memory, as well as its local memory. Hereinafter referred to as RMAC).

In general, remote memory utilization technology is based on excellent network performance. The bandwidth of high-speed network cards such as ATM and Myrinet is about half of the memory bandwidth. Research on the utilization of remote memory is divided into three major areas: remote paging, cooperative caching, and distributed shared memory. Remote paging and cooperative caching is a technology that improves system I / O performance by reducing global I / O by placing a global memory layer between the physical memory system and the disk memory system layer of the existing operating system. The two systems are distinguished by whether global memory data content is shared between nodes. Distributed shared memory is a technology that provides end users with a programming interface that can use NOW's memories with independent address spaces as a single address space.

Memory usage in NOW is known to be on average 30% and no more than 70%. In addition, in a high-speed networked workstation environment with more than 1 Gbps of bandwidth, such as ATM, Myrinet, and Gigabit Ethernet, data access time from remote memory, the physical memory of another node, is more than 10 times that of local disk. It is known to be fast.

[Table 1] is a comparison of processor, memory, LAN bandwidth, and disk bandwidth. As shown in [Table 1], the processing speed of a processor and the bandwidth of communication equipment are rapidly developing, whereas the development of disk storage devices is shown. The speed is very slow. Accordingly, there is a need to utilize the memory of a remote workstation as its virtual memory or cache using a high speed network and a high performance processor rather than using only its own disk storage device.

division 1985 1990's 1995 2000's Processor 1 GFlops 8 gflops 300 gflops 3 TFlops Memory 73 MB 2.3 GB 85 GB 720 GB LAN bandwidth 90 Mbps 380 Mbps 4.5 Gbps 38 Gbps Disk Bandwidth (SCSI Standards) 5 MB / sec 10 MB / sec 20 MB / sec Under 40 MB / sec development

Therefore, an object of the present invention is to back up the data stored in this memory to the remote memory when real memory pages need to be reallocated to the local disk due to lack of physical memory, so that the local disk can be stored next time this data is needed. To provide a remote memory access channel device and method for network virtual memory that can be read from the remote memory to improve the input and output performance of the workstation.

In accordance with another aspect of the present invention, there is provided a remote memory access channel apparatus for network virtual memory, comprising: an RMAC client for intercepting a ll_rw_page () function, which is a disk memory system interface, and caching a memory page in a remote memory; A remote memory access channel server for which RMAC provides remote memory to other workstations as a server; A remote memory access channel register for maintaining a consistent list of RMACs; A list of stored remote memory access channels maintained and managed by the remote memory access channel client; A remote memory access channel storage list maintained and maintained by the remote memory access channel server; And a remote memory access channel list maintained and managed by the remote memory access channel register.

In addition, in the remote memory access method for network virtual memory according to the present invention, when the network virtual memory system and the file system call the ll_rw_page () function for disk writing, the RMAC client selects an appropriate remote memory from the list through a replacement algorithm. A first step of doing; Sending a " write request message " that caches a disk write requested memory page to an RMAC server providing the remote memory selected from the first step; A third step of adding content cached to the stored remote memory access channel list from the second step; And a fourth step of storing the memory page in the disk memory if the data content of the memory page for which the disk write request has been changed from the second step.

In addition, in the remote memory access method for network virtual memory according to the present invention, when the network virtual memory system and the file system call the ll_rw_page () function for disk reading, the RMAC client intercepts this function and examines the stored RMAC list. A first step of verifying that the requested memory page is cached in the remote memory; A second step of transmitting an RMAC read request message for reading the requested memory page to the RMAC server if cached from the first step, and calling the ll_rw_page () function, which is an interface originally provided by the disk memory system, if not cached; ; A third step of checking if the RMAC server receives the RMAC read request message from the second step and examining the storage RMAC list to cache the requested memory page; If it is caching from the third step, it makes an RMAC read request response message with the requested memory page and sends it to the RMAC client to delete the requested memory page item from the storage RMAC list, and if it is not caching, sends an RMAC read error message to the RMAC client. It characterized in that it comprises a fourth step of transmitting to.

The present invention also provides a method comprising: a first step of, when the ll_rw_page () function is called, an RMAC client selects an appropriate remote memory through a replacement algorithm in a list; Sending a " write request message " that caches a disk write requested memory page to an RMAC server providing the remote memory selected from the first step; A third step of adding content cached to the stored remote memory access channel list from the second step; Performing a fourth step of storing the memory page in the disk memory if the data content of the memory page for which the disk write request has been changed from the second step is performed by the network virtual memory system and the file system to perform disk writing; calling the ll_rw_page () function, intercepting this function to ensure that the RMAC client examines the stored RMAC list to verify that the requested memory page is cached in the remote memory; A second step of transmitting an RMAC read request message for reading the requested memory page to the RMAC server if cached from the first step, and calling the ll_rw_page () function, which is an interface originally provided by the disk memory system, if not cached; ; A third step of checking if the RMAC server receives the RMAC read request message from the second step and examining the storage RMAC list to cache the requested memory page; If it is caching from the third step, it creates an RMAC read request response message with the requested memory page and sends it to the RMAC client to delete the requested memory page item from the storage RMAC list, and if it is not caching, request an RMAC read error message. And a computer-readable recording medium having recorded thereon a program for executing a disk read by the network virtual memory system and the file system by performing a fourth step of transmitting to the RMAC client.

1 illustrates a remote memory access channel write processing mechanism applied to the present invention.

Figure 2 illustrates a remote memory access channel read processing mechanism applied to the present invention.

3 is a schematic diagram of a remote memory access channel in accordance with the present invention.

<Description of Signs of Major Parts of Drawings>

1: RMAC Client 2: RMAC Server

3: RMAC Register 4: Stored RMAC List

5: Storing RMAC List 6: Hard Disk Controllers

7: local disk controller

The present invention largely consists of three sub-systems, such as RMAC client 1, RMAC server 2, and RMAC register 3. The main data structures are stored RMAC list (4), storing RMAC list (5), and RMAC list, which are in turn maintained and managed by the RMAC client (1), the RMAC server (2), and the RMAC register (3).

Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.

1 is a diagram showing a remote memory access channel write processing mechanism applied to the present invention, FIG. 2 is a diagram showing a remote memory access channel read processing mechanism applied to the present invention, and FIG. 3 is a remote according to the present invention. Memory access channel structure diagram.

First, the structure of the RMAC will be described first.

1. RMAC List

A data structure used to provide information about the currently available remote memory. It contains an RMAC server identifier that identifies each RMAC server in NOW, an RMAC identifier that distinguishes remote memory pages from each other within each RMAC server, and an age that provides the importance of this remote memory page.

2. RMAC Register (3)

Network virtual memory systems in NOW will each have a RMAC list of the same content. The RMAC register is a subsystem that maintains a consistent list of RMACs. The RMAC registers of each node cooperate with each other to keep the RMAC list consistent.

3.Stored RMAC List (4)

A data structure that RMAC uses as a client to maintain and maintain information about caching its memory pages in remote memory. It has an item consisting of an RMAC server identifier, an RMAC identifier, and a disk memory page identifier that distinguishes a disk memory page from each other.

4. RMAC Client (1)

A subsystem that caches memory pages in remote memory by intercepting the ll_rw_page () function, a disk memory system interface. Stored RMAC list manages information about memory pages that are currently cached.

5. Storing RMAC List (5)

Data structure used by RMAC to manage the caching of memory pages from other nodes as a server. It has an item consisting of an RMAC client identifier, an RMAC identifier, and a physical memory page identifier that identifies a physical memory page.

6. RMAC Server (2)

RMAC is a subsystem that provides remote memory to other workstations as a server. Storing RMAC list manages the current cache.

Second, looking at the communication protocol between RMACs, RMACs communicate with each other through the following messages.

1. RMAC List Message

Messages exchanged between RMAC registrars to maintain currently available remote memory information.

2. RMAC Write Request Message

Message used by the RMAC client to request caching of memory pages from the RMAC server.

3. RMAC Read Request Message

Sent by an RMAC client to an RMAC server to read a page of memory previously cached in remote memory.

4. RMAC Read Request Response Message

Message used to deliver the requested memory page to the RMAC client if the RMAC server is caching the requested memory page when it receives an RMAC read request message.

5. RMAC Read Error Message

A message used to notify an RMAC client that a read request has failed when the RMAC server receives an RMAC read request message and is not caching the requested memory page.

6. RMAC List Message

Messages exchanged between RMAC registrars to maintain currently available remote memory information.

Third, the basic operation of network virtual memory is as follows.

The network virtual memory system performs the following basic operations.

1. Managing the RMAC Cache List

The RMAC list is managed by the RMAC register 3. Each RMAC register 3 constituting the network virtual memory system is driven at regular time intervals by a timer interrupt. The RMAC register 3 conveys information about the remote memory that it can provide to other RMACs by the following mechanism.

1) Check if the workstation is currently in use.

2) If the workstation is currently busy, send a blank RMAC list message to each RMAC register.

3) If the current workstation is not in use, it sends a message to the RMAC register that contains the contents of the currently stored RMAC list and the contents of the RMAC list that it can provide to remote memory.

4) The RMAC Registrar who received the message removes the previous items related to the RMAC that sent the message from its RMAC list and corrects the newly received content.

2. Network Virtual Memory Replacement Algorithm

The network virtual memory system performs a replacement algorithm based on the LRU. Each remote memory page in the RMAC list has an age, of which the memory page with the highest age is selected.

3. Handling of RMAC Write Requests

When the network virtual memory system and the file system call the ll_rw_page () function for disk writing, the RMAC client 1 intercepts and processes as follows.

1) The RMAC client 1 selects the appropriate remote memory via a replacement algorithm from the list (102, 103).

2) Send 104 a " write request message " that caches a memory write requested memory page to the RMAC server 2 providing the selected remote memory.

3) The cached content is added to the stored RMAC list 4 (105).

4) If the data content of the memory page for which the disk write request has been changed, the memory page is stored in the disk memory 6 (106).

4. Processing RMAC Write Request Messages

When the RMAC server 2 receives the RMAC write request message, it processes by the following mechanism.

1) Check if the workstation is currently in use.

2) If the workstation is not in use, memory pages are allocated from the physical memory system.

3) Cache Stores the requested memory page.

4) The cached information is stored in the Storing RMAC list (5).

5) Ignore the message if the workstation is busy.

6) For the RMAC write request message, the RMAC server 2 does not send an acknowledgment message directly, with or without success, and later delivers it by the RMAC list message.

5. Processing RMAC Read Request Messages

When the network virtual memory system and the file system call the ll_rw_page () function to read a disk, the function is intercepted (201), and the RMAC client 1 processes as follows.

1) The RMAC client 1 examines the Stored RMAC List 4 to see if the requested memory page has been cached in the remote memory (202, 203).

2) If cached, sends an RMAC weather request message to the RMAC server 2 which reads the requested memory page (204, 207).

3) The process blocks. If it is not cached, the ll_rw_page () function, which is the interface originally provided by the disk memory system 7, is called (208).

6. Handling of RMAC Read Request Messages

When the RMAC server 2 receives the RMAC read request message, it processes by the following mechanism (205, 206).

1) Examine the Storing RMAC list 5 to see if it is caching the requested memory page.

2) If caching, an RMAC read request response message is created with the requested memory page and sent to the RMAC client (1).

3) The requested memory page item is deleted from the Storing RMAC list (5).

4) If not caching, send an RMAC read error message to the requesting RMAC client (1).

7. Handling RMAC Read Error Messages

When the RMAC client 1 receives an RMAC read error message, the memory page is read from the disk memory by calling ll_rw_page (), which is an interface originally provided by the disk memory system.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited.

As noted above, the present invention uses a network virtual memory that allows any workstation to use not only its local memory but also the memory of the remote workstation as if it were its memory by applying the remote memory access channel device to NOW. This allows the area of local memory to be extended to remote memory areas.

In addition, the proposed remote memory access channel apparatus and method for network virtual memory is located in the middle layer of the physical memory system and the local disk system of the existing operating system, and reallocates the physical memory page to the hard disk due to lack of physical memory. In some cases, the data stored in memory is backed up to the memory of the remote workstation that is not currently in use, so that the next time this data is needed, the I / O performance is read from the remote workstation's memory on the network without loading from the workstation's hard disk. Can be improved.

Claims (4)

A remote memory access channel (RMAC) client for intercepting the ll_rw_page () function, which is a disk memory system interface, for caching memory pages into remote memory; A remote memory access channel server for which RMAC provides remote memory to other workstations as a server; A remote memory access channel register for maintaining a consistent list of RMACs; A list of stored remote memory access channels maintained and managed by the remote memory access channel client; A remote memory access channel storage list maintained and maintained by the remote memory access channel server; And a remote memory access channel list maintained and managed by the remote memory access channel register. When the network virtual memory system and the file system call the ll_rw_page () function for disk writing, the RMAC client selecting a suitable remote memory through a replacement algorithm from a list; Sending a " write request message " that caches a disk write requested memory page to an RMAC server providing the remote memory selected from the first step; A third step of adding content cached to the stored remote memory access channel list from the second step; And a fourth step of storing the memory page in the disk memory if the data content of the memory page requested to write the disk from the second step is changed. When the network virtual memory system and the file system call the ll_rw_page () function for disk reads, the first step is to intercept this function so that the RMAC client examines the stored RMAC list to verify that the requested memory page is cached in remote memory. ; A second step of sending an RMAC diary request message for reading the requested memory page to the RMAC server if cached from the first step, and calling the ll_rw_page () function, which is an interface originally provided by the disk memory system, if not cached; ; A third step of checking if the RMAC server receives the RMAC read request message from the second step and examining the storage RMAC list to cache the requested memory page; If it is caching from the third step, it creates an RMAC read request response message with the requested memory page and sends it to the RMAC client to delete the requested memory page item from the storage RMAC list, and if it is not caching, request an RMAC read error message. And a fourth step of transmitting to the RMAC client. calling the ll_rw_page () function, the RMAC client selecting a suitable remote memory through a replacement algorithm from a list; Sending a " write request message " that caches a disk write requested memory page to an RMAC server providing the remote memory selected from the first step; A third step of adding content cached to the stored remote memory access channel list from the second step; Performing a fourth step of storing the memory page in the disk memory if the data content of the memory page for which the disk write request has been changed from the second step is performed by the network virtual memory system and the file system to perform disk writing; calling the ll_rw_page () function, intercepting this function to ensure that the RMAC client examines the stored RMAC list to verify that the requested memory page is cached in the remote memory; A second step of sending an RMAC diary request message for reading the requested memory page to the RMAC server if cached from the first step, and calling the ll_rw_page () function, which is an interface originally provided by the disk memory system, if not cached; ; A third step of checking if the RMAC server receives the RMAC read request message from the second step and examining the storage RMAC list to cache the requested memory page; If it is caching from the third step, it creates an RMAC read request response message with the requested memory page and sends it to the RMAC client to delete the requested memory page item from the storage RMAC list, and if it is not caching, request an RMAC read error message. A computer-readable recording medium having recorded thereon a program for executing a step of performing a disk read by a network virtual memory system and a file system by performing a fourth step of transmitting to an RMAC client.