Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: 371f7ad0ed89cd9ca8034690e3986ba7ddcc24ca
https://github.com/WebKit/WebKit/commit/371f7ad0ed89cd9ca8034690e3986ba7ddcc24ca
Author: Nipun Shukla <[email protected]>
Date: 2026-05-21 (Thu, 21 May 2026)
Changed paths:
M Source/JavaScriptCore/jit/JITWorklistThread.cpp
M Source/JavaScriptCore/runtime/OptionsList.h
M Source/WTF/wtf/NumberOfCores.cpp
M Source/WTF/wtf/NumberOfCores.h
M Source/WTF/wtf/Threading.cpp
M Source/WTF/wtf/Threading.h
Log Message:
-----------
Give JIT helper threads QOS_UTILITY on less powerful devices
https://bugs.webkit.org/show_bug.cgi?id=315203
rdar://177532305
Reviewed by Marcus Plutowski and Dan Hecht.
On devices with only 2 P-cores, JIT worklist threads run at the same
QOS as the main threads, causing P-core contention. Sustained P-cluster
load also pushes less powerful devices into thermal throttling,
causing performance losses.
This change lowers JIT worklist thread priority to QOS::Utility on
small devices, defined as <=2 P-cores or <=6 logical cores. JIT threads
can then run on E-cores and free the P-cluster. This causes regression
on more powerful devices so we keep existing behavior there.
There are no functional changes associated with this commit.
* Source/JavaScriptCore/jit/JITWorklistThread.cpp:
(JSC::JITWorklistThread::threadDidStart):
* Source/JavaScriptCore/runtime/OptionsList.h:
* Source/WTF/wtf/NumberOfCores.cpp:
(WTF::numberOfPerformanceProcessorCores):
* Source/WTF/wtf/NumberOfCores.h:
* Source/WTF/wtf/Threading.cpp:
(WTF::Thread::setCurrentThreadIsUtility):
* Source/WTF/wtf/Threading.h:
Canonical link: https://commits.webkit.org/313672@main
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