On Tue, May 17, 2016 at 10:22:18PM -0700, NGie Cooper wrote: > > > On May 17, 2016, at 20:55, Mark Johnston <ma...@freebsd.org> wrote: > > > > 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); > > + } > > Use predict_false?
I don't think that's really warranted here. A __predict_false could become incorrect after a future change elsewhere in this function, and this isn't enough of a hot path for such a change to make a measurable difference on its own. > > > > #ifdef HWPMC_HOOKS > > if (PMC_CPU_HAS_SAMPLES(PCPU_GET(cpuid))) > > _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
