Date: Wed, 12 Apr 2023 13:08:57 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 270785] Performance and power efficiency regression due to pthread_cond_timedwait() changes Message-ID: <bug-270785-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D270785 Bug ID: 270785 Summary: Performance and power efficiency regression due to pthread_cond_timedwait() changes Product: Base System Version: 13.2-RELEASE Hardware: Any OS: Any Status: New Severity: Affects Some People Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: bllcha013@myuct.ac.za After updating from 13.1-RELEASE-p7 to 13.2-RELEASE-p0, I experienced a performance and power efficiency regression especially when running Java programs, in particular the Minecraft server. After some testing, this appears to be caused by commit e21c77f80c3b1cf2bd0a9f874e15e7a8e49f0dba [Improve timeout precision of pthread_cond_timedwait().]. When building the kernel just before this commi= t, this regression does not occur, while building with this commit (n253051-e21c77f80c3b), the regression occurs. The regression is still pres= ent in the 6 April 2023 snapshot kernel of 14.0-CURRENT. I have observed this behavior on two systems, a server with an Intel Xeon X= 3460 (Lynnfield, Nehalem) CPU, as well as a desktop PC with an Intel Core i7-670= 0K (Skylake) CPU. When running a kernel with this commit, the WCPU usage of the java process = in top is considerably higher at idle than without the commit when running a Minecraft server (1 to 2% before, 10% to 30% after). In addition, the CPU spends a lot more time in less power efficient C-states (C1) where before t= his commit, the CPU spends much more time in power efficient C-states such as C= 3. On my server, the CPU used to spend 98% time in C3 while after the commit it spends only 30% time in C3, leading to higher power consumption, more heat,= and faster fan speeds. --=20 You are receiving this mail because: You are the assignee for the bug.=
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