Date: Fri, 10 Sep 2010 13:24:47 +0000 (UTC) From: Alexander Motin <mav@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r212416 - head/sys/kern Message-ID: <201009101324.o8ADOld7047277@svn.freebsd.org>
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Author: mav Date: Fri Sep 10 13:24:47 2010 New Revision: 212416 URL: http://svn.freebsd.org/changeset/base/212416 Log: Do not IPI CPU that is already spinning for load. It doubles effect of spining (comparing to MWAIT) on some heavly switching test loads. Modified: head/sys/kern/sched_ule.c Modified: head/sys/kern/sched_ule.c ============================================================================== --- head/sys/kern/sched_ule.c Fri Sep 10 12:55:36 2010 (r212415) +++ head/sys/kern/sched_ule.c Fri Sep 10 13:24:47 2010 (r212416) @@ -196,7 +196,7 @@ static int preempt_thresh = 0; #endif static int static_boost = PRI_MIN_TIMESHARE; static int sched_idlespins = 10000; -static int sched_idlespinthresh = 4; +static int sched_idlespinthresh = 64; /* * tdq - per processor runqs and statistics. All fields are protected by the @@ -208,6 +208,7 @@ struct tdq { struct mtx tdq_lock; /* run queue lock. */ struct cpu_group *tdq_cg; /* Pointer to cpu topology. */ volatile int tdq_load; /* Aggregate load. */ + volatile int tdq_cpu_idle; /* cpu_idle() is active. */ int tdq_sysload; /* For loadavg, !ITHD load. */ int tdq_transferable; /* Transferable thread count. */ short tdq_switchcnt; /* Switches this tick. */ @@ -966,7 +967,7 @@ tdq_notify(struct tdq *tdq, struct threa * If the MD code has an idle wakeup routine try that before * falling back to IPI. */ - if (cpu_idle_wakeup(cpu)) + if (!tdq->tdq_cpu_idle || cpu_idle_wakeup(cpu)) return; } tdq->tdq_ipipending = 1; @@ -2545,8 +2546,14 @@ sched_idletd(void *dummy) } } switchcnt = tdq->tdq_switchcnt + tdq->tdq_oldswitchcnt; - if (tdq->tdq_load == 0) - cpu_idle(switchcnt > 1); + if (tdq->tdq_load == 0) { + tdq->tdq_cpu_idle = 1; + if (tdq->tdq_load == 0) { + cpu_idle(switchcnt > sched_idlespinthresh); + tdq->tdq_switchcnt++; + } + tdq->tdq_cpu_idle = 0; + } if (tdq->tdq_load) { thread_lock(td); mi_switch(SW_VOL | SWT_IDLE, NULL);
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