Data processing system and method for executing snapshot dumps

• US 5,644,701 A
• Filed: 12/28/1994
• Issued: 07/01/1997
• Est. Priority Date: 12/29/1993
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Takewaki, Toshiaki
• Primary Examiner(s): Beausoliel, Jr., Robert W.
• Assistant Examiner(s): Palys, Joseph E.
• Application Number:
  US08/365,545
• Time in Patent Office: 916 Days
• Field of Search: 395/182.18, 395/182.17, 395/182.13, 395/181, 395/471, 395/473, 395/469, 395/470
• US Class Current: 714/20
• CPC Class Codes: G06F 11/1407 Checkpointing the instruction stream

Abstract

At the time of a snapshot dump, a main memory storage unit stores only the memory contents of the dirty ones whose contents have changed of the pages in the main memory after the execution of the preceding snapshot dump. Data indicating the storage location of the contents of the pages stored at that time is stored in a storage device in pages in the form of a storage location list. Furthermore, data indicating the storage location of page contents is stored in a storage location list storage area each time a snapshot dump is executed. When the memory contents of a given snapshot dump are restored, the corresponding location list is taken out from the storage location list storage area. According to the storage location list, the corresponding memory contents are restored into the original page location in the main memory.

Claims

1. A data processing system with a main memory that stores data in pages, comprising:

storage means for storing memory dumps of said main memory;

location list storage means for storing lists indicating locations of memory contents on said storage means; and

means for executing snapshot dumps in a constant period including;

means for storing into said storage means memory contents of said main memory changed during the time between a preceding snapshot dump execution and a current snapshot dump execution,

means for creating location lists indicating locations of the memory contents on said storage means, and

means for storing the created location lists in said location list storage means.

2. A system according to claim 1, wherein each page of said main memory contains a status flag indicating whether or not its own memory content has changed.

3. A data processing system with a main memory that stores data in pages, comprising:

a write-through-type cache memory storing a copy of part of the main memory data in blocks and containing address data of the blocks in said main memory and status flags indicating whether its own block is valid or invalid;

first storage means for storing memory dumps of said main memory;

second storage means for storing memory dumps of said cache memory;

means for executing snapshot dumps in a constant period including;

means for storing into said first storage means memory contents of said main memory changed during the time between a preceding snapshot dump execution and a current snapshot dump execution, and

means for storing into said second storage means the address data corresponding to valid ones of the blocks in said cache memory;

first restoring means for writing back into said main memory the memory contents stored in said first storage means; and

second restoring means for, on the basis of the address data stored in said second storage means, writing back into said cache memory the memory contents corresponding to the address data among the memory contents written back into said main memory.

4. A data processing system with a main memory that stores data in pages, comprising:

a copy-back-type cache memory storing a copy of part of the main memory data in blocks and containing address data of the blocks in said main memory and status flags indicating whether its own block is clean, dirty, or invalid;

first storage means for storing memory dumps of said main memory;

second storage means for storing memory dumps of said cache memory;

means for executing snapshot dumps in a constant period including;

means for writing back into said main memory memory contents of the blocks containing status flags indicating a dirty state in said cache memory, without changing the dirty state indications of the status flags,

means for storing into said second storage means the address data and the status flags contained in the blocks having status flags indicating a dirty or clean state in said cache memory, and

means for storing into said first storage means memory contents of said main memory changed during the time between a preceding snapshot dump execution and a current snapshot dump execution;

first restoring means for writing back into said main memory the memory contents stored in said first storage means; and

second restoring means for writing back into said cache memory the memory contents corresponding to the address data stored in said second storage means among the memory contents written back into said main memory, and the status flags stored in said second storage means.

5. A data processing system with a main memory that stores data in pages and a plurality of processors that share said main memory, comprising:

a plurality of snooping-type cache memories provided in each of said plurality of processors, storing a copy of part of the main memory data in blocks and containing address data of the blocks in said main memory, status flags indicating whether its own block is clean, dirty, or invalid, and writing-back status flags indicating whether or not memory contents of its own block has been written back into said main memory;

first storage means for storing memory dumps of said main memory;

second storage means for storing memory dumps of said cache memories;

means for executing snapshot dumps in a constant period including;

means for setting all of the writing-back status flags in said cache memories to a non-written-back state,

means for writing back into said main memory the memory contents of the blocks containing writing-back status flags indicating the non-written-back state and a status flag indicating a dirty state in said cache memories, without changing the dirty state indications of the status flags,

means for storing into said second storage means the address data corresponding to the blocks containing the status flags indicating a dirty or clean state, and the corresponding status flags of the blocks in said cache memories, and

means for storing into said first storage means memory contents of said main memory changed during the time between a preceding snapshot dump execution and a current snapshot dump execution;

first restoring means for writing back into said main memory the memory contents stored in said first storage means; and

second restoring means for writing back into said cache memories the memory contents corresponding to the address data stored in said second storage means among the memory contents written back into said main memory, and the corresponding status flags in said second storage means.

6. A data processing system with a main memory that stores data in pages and a plurality of processors that share said main memory, comprising:

a plurality of cache memories provided in each of said plurality of processors, storing a copy of part of the main memory data in blocks;

directory memory means, connected to said cache memories, for storing address data of the blocks in said main memory contained in each of said cache memories, status flags indicating whether its own block is clean, dirty, or invalid, and cache list data indicating cache memories containing the blocks;

first storage means for storing memory dumps of said main memory;

second storage means for storing memory dumps of said cache memories;

means for executing snapshot dumps in a constant period including;

means for, in reference to said directory memory means, writing back into said main memory the memory contents of the blocks containing a status flag indicating a dirty state in said cache memories,

means for, in reference to said directory memory means, storing into said second storage means the address data corresponding to the blocks containing the status flags indicating a dirty or clean state, the corresponding status flags, and the cache list data, and

means for storing into said first storage means memory contents of said main memory changed during the time between a preceding snapshot dump execution and a current snapshot dump execution;

first restoring means for writing back into said main memory the memory contents stored in said first storage means;

second restoring means for writing back into said directory memory means the address data, the status flags, and the cache list data stored in said second storage means; and

third restoring means for, on the basis of the address data and the cache list data written back into said directory memory means, writing back into said cache memories designated by said cache list data the memory contents corresponding to the address data among the memory contents written back into said main memory, by said first restoring means.

7. In a data processing system with a main memory, a method for executing snapshot dumps of said main memory, comprising the steps of:

executing snapshot dumps in a constant period to retain memory contents of said main memory, including;

storing memory contents of said main memory changed after executing a preceding snapshot dump in connection with a number of the snapshot dump executions in which said memory contents are stored;

creating location lists indicating stored locations of the memory contents;

storing the created location lists; and

writing back into said main memory the memory contents stored in connection with the number of the snapshot dump executions in which said memory contents are stored by referring to said stored location lists.