On Wednesday, October 24, 2012 2:36:41 pm Jim Harris wrote: > Author: jimharris > Date: Wed Oct 24 18:36:41 2012 > New Revision: 242014 > URL: http://svn.freebsd.org/changeset/base/242014 > > Log: > Pad tdq_lock to avoid false sharing with tdq_load and tdq_cpu_idle. > > This enables CPU searches (which read tdq_load) to operate independently > of any contention on the spinlock. Some scheduler-intensive workloads > running on an 8C single-socket SNB Xeon show considerable improvement with > this change (2-3% perf improvement, 5-6% decrease in CPU util). > > Sponsored by: Intel > Reviewed by: jeff > > Modified: > head/sys/kern/sched_ule.c > > Modified: head/sys/kern/sched_ule.c > ============================================================================== > --- head/sys/kern/sched_ule.c Wed Oct 24 18:33:44 2012 (r242013) > +++ head/sys/kern/sched_ule.c Wed Oct 24 18:36:41 2012 (r242014) > @@ -223,8 +223,13 @@ static int sched_idlespinthresh = -1; > * locking in sched_pickcpu(); > */ > struct tdq { > - /* Ordered to improve efficiency of cpu_search() and switch(). */ > + /* > + * Ordered to improve efficiency of cpu_search() and switch(). > + * tdq_lock is padded to avoid false sharing with tdq_load and > + * tdq_cpu_idle. > + */ > struct mtx tdq_lock; /* run queue lock. */ > + char pad[64 - sizeof(struct mtx)];
Can this use 'tdq_lock __aligned(CACHE_LINE_SIZE)' instead? -- John Baldwin _______________________________________________ svn-src-head@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
