Bug 101390 – Copying phase should use work lists

• Component: JavaScriptCore
• Status: RESOLVED FIXED

[Mark Hahnenberg]

Currently we iterate over every cell in the Heap during the copying phase. To improve our performance under paging, we'd like to reduce the number of pages we touch during a collection. One way to avoid having to iterate every cell during copying is to use per-CopiedBlock work lists created during the marking phase to record just the JSCells that need to be revisited during the copying phase. Then, during the copying phase, we iterate over all the CopiedBlocks and use their accumulated work lists to perform the necessary copying.

[Mark Hahnenberg]

Created attachment 172651 [details]
Patch

[Filip Pizlo]

Comment on attachment 172651 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=172651&action=review

> Source/JavaScriptCore/heap/CopiedBlock.h:83
> +    typedef Vector<JSCell*, blockSize / (sizeof(JSValue) * 4)> WorkList;

Would be better to conserve space for these wordlists somehow!

[Geoffrey Garen]

Mark, you mentioned reduced paging as a benefit to this strategy. How can we measure that?

[Mark Hahnenberg]

Created attachment 176542 [details]
Patch

[WebKit Review Bot]

Comment on attachment 176542 [details]
Patch

Rejecting attachment 176542 [details] from commit-queue.

Failed to run "['/mnt/git/webkit-commit-queue/Tools/Scripts/webkit-patch', '--status-host=queues.webkit.org', '-..." exit_code: 2

Last 500 characters of output:
commit-queue/Source/WebKit/chromium/third_party/v8-i18n --revision 159 --non-interactive --force --accept theirs-conflict --ignore-externals' in '/mnt/git/webkit-commit-queue/Source/WebKit/chromium'
51>At revision 159.

________ running '/usr/bin/python tools/clang/scripts/update.py --mac-only' in '/mnt/git/webkit-commit-queue/Source/WebKit/chromium'

________ running '/usr/bin/python gyp_webkit' in '/mnt/git/webkit-commit-queue/Source/WebKit/chromium'
Updating webkit projects from gyp files...

Full output: http://queues.webkit.org/results/15027601

[Mark Hahnenberg]

Committed r136077: <http://trac.webkit.org/changeset/136077>