Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: 0839f9342ed5056785ce58ed9c5a0f92b323f625
https://github.com/WebKit/WebKit/commit/0839f9342ed5056785ce58ed9c5a0f92b323f625
Author: Yusuke Suzuki <[email protected]>
Date: 2026-08-29 (Sat, 29 Aug 2026)
Changed paths:
A JSTests/stress/warm-up-marked-blocks-state-machine.js
A JSTests/stress/warm-up-marked-blocks.js
M Source/JavaScriptCore/heap/FastMallocAlignedMemoryAllocator.cpp
M Source/JavaScriptCore/heap/FastMallocAlignedMemoryAllocator.h
M Source/JavaScriptCore/runtime/OptionsList.h
M Source/JavaScriptCore/tools/JSDollarVM.cpp
Log Message:
-----------
[JSC] Introduce JSC WarmUpThread for MarkedBlocks
https://bugs.webkit.org/show_bug.cgi?id=322774
rdar://186036234
Reviewed by Marcus Plutowski and Dan Hecht.
System page size is 16KB (on Darwin at least) and MarkedBlock size is
also 16KB. We end up having a page-fault for each MarkedBlock allocation
and it is really costly when it is executed synchronously. On M5 device,
each page-fault cost is 700ns.
This patch introduces WarmUpBlockProvider. This holds its own helper
thread via AutomaticThread, and offering a pre-page-faulted warmed-up
MarkedBlocks if possible. This manages a buffer of pre-page-faulted pages
and provides them. If it is exhausted, thread is launched / acked and
start allocating a new pages and perform page-fault concurrently to the
mutator.
Memory scores (Membuster7 / PLUM4) are both neutral.
* JSTests/stress/warm-up-marked-blocks-state-machine.js: Added.
* JSTests/stress/warm-up-marked-blocks.js: Added.
(shouldBe):
* Source/JavaScriptCore/heap/FastMallocAlignedMemoryAllocator.cpp:
(JSC::warmUpMarkedBlockStateForTesting):
(JSC::setWarmUpMarkedBlockAllocationShouldFailForTesting):
(JSC::FastMallocAlignedMemoryAllocator::tryAllocateAlignedMemory):
* Source/JavaScriptCore/heap/FastMallocAlignedMemoryAllocator.h:
* Source/JavaScriptCore/runtime/OptionsList.h:
* Source/JavaScriptCore/tools/JSDollarVM.cpp:
(JSC::JSC_DEFINE_HOST_FUNCTION):
(JSC::JSDollarVM::finishCreation):
Canonical link: https://commits.webkit.org/320112@main
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