65445 2011-07-31 21:34:07 -0700 JSC does a GC even when the heap still has free pages 2011-08-02 12:57:24 -0700 1 1 1 Unclassified WebKit JavaScriptCore 528+ (Nightly build) All All RESOLVED FIXED P2 Normal --- 1 fpizlo webkit-unassigned fpizlo oliver slewis webkit.review.bot oldest_to_newest 444512 0 fpizlo 2011-07-31 21:34:07 -0700 The JSC GC has an elastic notion of free memory, where free blocks left over from a previous garbage collection are steadily returned to the OS provided that the application does not experience a subsequent heap usage spike that would need those blocks again. But the GC does not leverage this as well as it could. It separately maintains a watermark limit for invoking collection. This limit is independent of the number of free pages. Thus, if an application experiences a memory usage peak where the heap is grown, and then memory usage dips resulting in a lower watermark, then the heap will be in the following awkward state: the free block pool will still have blocks available for immediate use in allocations, but the collector will insist on running anyway. Ideally, the elasticity of the free block pool should be coupled to the GC's decision function for when to invoke collection, so that we don't do full collections when there is still free memory available. 444515 1 102476 fpizlo 2011-07-31 21:53:31 -0700 Created attachment 102476 the patch 445452 2 102476 webkit.review.bot 2011-08-02 12:57:20 -0700 Comment on attachment 102476 the patch Clearing flags on attachment: 102476 Committed r92217: <http://trac.webkit.org/changeset/92217> 445453 3 webkit.review.bot 2011-08-02 12:57:24 -0700 All reviewed patches have been landed. Closing bug. 102476 2011-07-31 21:53:31 -0700 2011-08-02 12:57:20 -0700 the patch elasticheapsize_patch_2.diff text/plain 4713 fpizlo SW5kZXg6IFNvdXJjZS9KYXZhU2NyaXB0Q29yZS9DaGFuZ2VMb2cKPT09PT09PT09PT09PT09PT09 PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PQotLS0gU291 cmNlL0phdmFTY3JpcHRDb3JlL0NoYW5nZUxvZwkocmV2aXNpb24gOTIwOTgpCisrKyBTb3VyY2Uv SmF2YVNjcmlwdENvcmUvQ2hhbmdlTG9nCSh3b3JraW5nIGNvcHkpCkBAIC0xLDMgKzEsMzMgQEAK KzIwMTEtMDctMzEgIEZpbGlwIFBpemxvICA8ZnBpemxvQGFwcGxlLmNvbT4KKworICAgICAgICBK U0MgZG9lcyBhIEdDIGV2ZW4gd2hlbiB0aGUgaGVhcCBzdGlsbCBoYXMgZnJlZSBwYWdlcworICAg ICAgICBodHRwczovL2J1Z3Mud2Via2l0Lm9yZy9zaG93X2J1Zy5jZ2k/aWQ9NjU0NDUKKworICAg ICAgICBSZXZpZXdlZCBieSBOT0JPRFkgKE9PUFMhKS4KKyAgICAgICAgCisgICAgICAgIElmIHRo ZSBoaWdoIHdhdGVybWFyayBpcyBub3QgcmVhY2hlZCwgdGhlbiB3ZSBhbGxvY2F0ZSBuZXcgYmxv Y2tzIGFzCisgICAgICAgIGJlZm9yZS4gIElmIHRoZSBjdXJyZW50IHdhdGVybWFyayBkb2VzIHJl YWNoIChvciBleGNlZWQpIHRoZSBoaWdoCisgICAgICAgIHdhdGVybWFyaywgdGhlbiB3ZSBjaGVj 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