Date: Wed, 18 May 2016 03:55:54 +0000 (UTC) From: Mark Johnston <markj@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r300110 - head/sys/kern Message-ID: <201605180355.u4I3tskK012821@repo.freebsd.org>
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Author: markj Date: Wed May 18 03:55:54 2016 New Revision: 300110 URL: https://svnweb.freebsd.org/changeset/base/300110 Log: Do not acquire the thread lock in hardclock_cnt() unless needed. This function only sets thread flags if a SIGPROF or SIGVTALRM timer has fired, which is almost never the case. MFC after: 2 weeks Modified: head/sys/kern/kern_clock.c Modified: head/sys/kern/kern_clock.c ============================================================================== --- head/sys/kern/kern_clock.c Wed May 18 03:50:21 2016 (r300109) +++ head/sys/kern/kern_clock.c Wed May 18 03:55:54 2016 (r300110) @@ -570,9 +570,11 @@ hardclock_cnt(int cnt, int usermode) flags |= TDF_PROFPEND | TDF_ASTPENDING; PROC_ITIMUNLOCK(p); } - thread_lock(td); - td->td_flags |= flags; - thread_unlock(td); + if (flags != 0) { + thread_lock(td); + td->td_flags |= flags; + thread_unlock(td); + } #ifdef HWPMC_HOOKS if (PMC_CPU_HAS_SAMPLES(PCPU_GET(cpuid)))
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