From ae154be1f34a674e6cbb43ccf6e442f56acd7a70 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 10 Sep 2009 14:40:57 +0200 Subject: sched: Weaken SD_POWERSAVINGS_BALANCE One of the problems of power-saving balancing is that under certain scenarios it is too slow and allows tons of real work to pile up. Avoid this by ignoring the powersave stuff when there's real work to be done. Signed-off-by: Peter Zijlstra LKML-Reference: Signed-off-by: Ingo Molnar --- kernel/sched_fair.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-) (limited to 'kernel/sched_fair.c') diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index 09d19f77eb3a..eaa00014b499 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -1333,10 +1333,25 @@ static int select_task_rq_fair(struct task_struct *p, int flag, int sync) for_each_domain(cpu, tmp) { /* - * If power savings logic is enabled for a domain, stop there. + * If power savings logic is enabled for a domain, see if we + * are not overloaded, if so, don't balance wider. */ - if (tmp->flags & SD_POWERSAVINGS_BALANCE) - break; + if (tmp->flags & SD_POWERSAVINGS_BALANCE) { + unsigned long power = 0; + unsigned long nr_running = 0; + unsigned long capacity; + int i; + + for_each_cpu(i, sched_domain_span(tmp)) { + power += power_of(i); + nr_running += cpu_rq(i)->cfs.nr_running; + } + + capacity = DIV_ROUND_CLOSEST(power, SCHED_LOAD_SCALE); + + if (nr_running/2 < capacity) + break; + } switch (flag) { case SD_BALANCE_WAKE: -- cgit v1.2.1