Buffer management strategies for flash-based storage systems
View Patent ↗Techniques are generally described related to a flash-based buffer management strategy. One example method to manage a buffer for a computer system may include maintaining a page-action list for monitoring a plurality of operations being executed on the computer system and utilizing a plurality of buffer pages of the buffer. An example page-action list may contain a hot-access queue for recently accessed buffer pages and a cold-access queue for less accessed buffer pages. The example method may also include, upon a determination that the buffer is full, identifying a victim buffer page from the plurality of buffer pages for eviction and evicting the victim buffer page from the buffer. The victim buffer page may be selected from the cold-access queue and based on a page weight, which is calculated based on a page state of the specific buffer page and a page hotness prediction for the specific buffer page might be accessed by an incoming operation.
1. A method to manage a buffer for a computer system, comprising:
maintaining a page-action list for monitoring a plurality of operations being executed on the computer system and utilizing a plurality of buffer pages of the buffer, wherein the page-action list contains a hot-access queue for recently accessed buffer pages and a cold-access queue for less accessed buffer pages;
upon a determination that the buffer is full, identifying a victim buffer page from the plurality of buffer pages for eviction, wherein the victim buffer page is selected from the cold-access queue and based on a page weight, which is calculated based on a page state of the specific buffer page and a page hotness prediction for the specific buffer page might be accessed by an incoming operation; and
evicting the victim buffer page from the buffer.
2. The method as recited in claim 1 , further comprising
during executing of a first operation which is selected from the plurality of operations and is accessing a first buffer page selected from the plurality of buffer pages, adding a first page-action referencing the first buffer page and storing the first operation's buffer action to the hot-access queue.
3. The method as recited in claim 2 , further comprising
upon determining that the first operation's buffer action is a write buffer action, setting a write weight state associated with the first buffer page to a high value.
4. The method as recited in claim 2 , further comprising
upon determining that the first operation's buffer action is a read buffer action and the first buffer page is referenced in the hot-access queue, setting a read weight state associated with the first buffer page to a high value.
5. The method as recited in claim 1 , further comprising:
moving a second page-action, referencing a second buffer page selected from the plurality of buffer pages, from the hot-access queue to the cold-access queue; and
setting a read weight state associated with the second buffer page to a low value.
6. The method as recited in claim 5 , further comprising:
removing a third page-action, referencing a third buffer page selected from the plurality of buffer pages, from the cold-access queue; and
setting a write weight state associated with the third buffer page to a low value.
7. The method as recited in claim 1 , wherein the victim buffer page is associated with a low read weight state and a low write weight state.
8. A system configured to manage a buffer for a computer system, comprising:
a page-action list containing a hot-access queue for recently accessed buffer pages and a cold-access queue for less accessed buffer pages; and
a buffer management module coupled with the page-action list, wherein the buffer management module is configured to
monitor a plurality of operations being executed on the computer system and utilizing a plurality of buffer pages of the buffer,
upon a determination that the buffer is full, identify a victim buffer page from the plurality of buffer pages for eviction, wherein the victim buffer page is selected from the cold-access queue and based on a page weight, which is calculated based on a page state of the specific buffer page and a page hotness prediction for the specific buffer page might be accessed by an incoming operation; and
evict the victim buffer page from the buffer.
9. The system as recited in claim 8 , wherein the buffer management module is further configured to
during executing of a first operation which is selected from the plurality of operations and is accessing a first buffer page selected from the plurality of buffer pages, add a first page-action referencing the first buffer page and storing the first operation's buffer action to the hot-access queue.
10. The system as recited in claim 9 , wherein the buffer management module is further configured to
upon determining that the first operation's buffer action is a write buffer action, set a write weight state associated with the first buffer page to a high value.
11. The system as recited in claim 9 , wherein the buffer management module is further configured to
upon determining that the first operation's buffer action is a read buffer action and the first buffer page is referenced in the hot-access queue, set a read weight state associated with the first buffer page to a high value.
12. The system as recited in claim 8 , wherein the buffer management module is further configured to:
move a second page-action, referencing a second buffer page selected from the plurality of buffer pages, from the hot-access queue to the cold-access queue; and
set a read weight state associated with the second buffer page to a low value.
13. The system as recited in claim 12 , wherein the buffer management module is further configured to:
remove a third page-action, referencing a third buffer page selected from the plurality of buffer pages, from the cold-access queue; and
set a write weight state associated with the third buffer page to a low value.
14. The system as recited in claim 8 , wherein the victim buffer page is associated with a low read weight state and a low write weight state.
15. A non-transitory machine-readable medium having a set of instructions which,
in response to execution by a processor, cause the processor to perform a method to manage a buffer for a computer system, the method comprising:
maintaining a page-action list for monitoring a plurality of operations being executed on the computer system and utilizing a plurality of buffer pages of the buffer, wherein the page-action list contains a hot-access queue for recently accessed buffer pages and a cold-access queue for less accessed buffer pages;
upon a determination that the buffer is full, identifying a victim buffer page from the plurality of buffer pages for eviction, wherein the victim buffer page is selected from the cold-access queue and based on a page weight, which is calculated based on a page state of the specific buffer page and a page hotness prediction for the specific buffer page might be accessed by an incoming operation; and
evicting the victim buffer page from the buffer.
16. The non-transitory machine-readable medium as recited in claim 15 , wherein the method further comprises
during executing of a first operation which is selected from the plurality of operations and is accessing a first buffer page selected from the plurality of buffer pages, adding a first page-action referencing the first buffer page and storing the first operation's buffer action to the hot-access queue.
17. The non-transitory machine-readable medium as recited in claim 16 , wherein the method further comprises:
upon determining that the first operation's buffer action is a write buffer action, setting a write weight state associated with the first buffer page to a high value; or
upon determining that the first operation's buffer action is a read buffer action and the first buffer page is referenced in the hot-access queue, setting a read weight state associated with the first buffer page to a high value.
18. The non-transitory machine-readable medium as recited in claim 15 , wherein the method further comprises:
moving a second page-action, referencing a second buffer page selected from the plurality of buffer pages, from the hot-access queue to the cold-access queue; and
setting a read weight state associated with the second buffer page to a low value.
19. The non-transitory machine-readable medium as recited in claim 18 , wherein the method further comprises:
removing a third page-action, referencing a third buffer page selected from the plurality of buffer pages, from the cold-access queue; and
setting a write weight state associated with the third buffer page to a low value.
20. The non-transitory machine-readable medium as recited in claim 15 , wherein the victim buffer page is associated with a low read weight state and a low write weight state.