Date: Wed, 12 Apr 2023 13:08:57 UTC
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=270785 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: firstname.lastname@example.org 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 commit, this regression does not occur, while building with this commit (n253051-e21c77f80c3b), the regression occurs. The regression is still present 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 X3460 (Lynnfield, Nehalem) CPU, as well as a desktop PC with an Intel Core i7-6700K (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 this commit, the CPU spends much more time in power efficient C-states such as C3. 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. -- You are receiving this mail because: You are the assignee for the bug.