Date: Thu, 9 Feb 2017 13:02:43 -0500 From: Ryan Stone <rysto32@gmail.com> To: FreeBSD Current <freebsd-current@freebsd.org> Subject: [PATCH] Check for preemption after lowering a thread's priority Message-ID: <CAFMmRNzr=bScqvWCpDqHvqhdmZJBEPt5_jy1CjVtfxUvSZ8KHQ@mail.gmail.com>
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I've just put up a phabricator review for a fix to ULE and 4BSD for a priority inversion problem. The issue is that after a running thread's priority is lowered (usually due to releasing a mutex and having a priority load revoked), the scheduler does not check whether the thread should now be preempted by a thread waiting in the runq. See this old ML post for a detailed description of one instance that I saw: https://lists.freebsd.org/pipermail/freebsd-current/2013-January/039261.html The review can be found here: https://reviews.freebsd.org/D9518
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