Date: Fri, 24 Jun 2022 09:38:28 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 264867] kevent EVFILT_TIMER, timer expiration with twice the period Message-ID: <bug-264867-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D264867 Bug ID: 264867 Summary: kevent EVFILT_TIMER, timer expiration with twice the period Product: Base System Version: 13.1-STABLE Hardware: amd64 OS: Any Status: New Severity: Affects Only Me Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: felice.tufo@gmail.com Attachment #234909 text/plain mime type: Created attachment 234909 --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=3D234909&action= =3Dedit example reproducing the problem I'm trying to use kevent to implement a periodic (50ms) event generator, the application can tolerate a 10% error on the programmed period. I know that FreeBSD is not a hard realtime OS, so just trying to evaluate how good it is for my specific needs. The problem is that every now and then (after some hours running) the timer expires well after the programmed period and what makes me think I'm running into an issue is that it happens *very* often with twice the programmed per= iod (100ms for a 50 ms programmed period... 40ms for a 20ms programmed period... etc.). Bug 264131 seems to be something similar, but that was deterministic behavi= our. Moreover I see the same problem on FreeBSD 12.2. I attach the example I use to reproduce the problem (using multithreading to make the issue happen faster). The example is compiled with clang on an updated FreeBSD 13.1 machine, on a skylake platform with 8-cores and 32Gb RAM, no other applications running (= not even sendmail). Thanks --=20 You are receiving this mail because: You are the assignee for the bug.=
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