diff options
| author | Siddha, Suresh B <suresh.b.siddha@intel.com> | 2007-05-08 00:32:48 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-05-08 11:15:17 -0700 |
| commit | bdecea3a9282d529b54954f3f1e59877629baba1 (patch) | |
| tree | c7330b1cec4b4a9bf18657bc99100276343efc38 /kernel/sched.c | |
| parent | 2bd7e20e0d24325b0799544bc8105cc57cc8e2aa (diff) | |
| download | lwn-bdecea3a9282d529b54954f3f1e59877629baba1.tar.gz lwn-bdecea3a9282d529b54954f3f1e59877629baba1.zip | |
sched: fix idle load balancing in softirqd context
Periodic load balancing in recent kernels happen in the softirq. In
certain -rt configurations, these softirqs are handled in softirqd context.
And hence the check for idle processor was always returning busy (as
nr_running > 1).
This patch captures the idle information at the tick and passes this info
to softirq context through an element 'idle_at_tick' in rq.
[kernel@kolivas.org: Fix reverse idle at tick logic]
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/sched.c')
| -rw-r--r-- | kernel/sched.c | 12 |
1 files changed, 5 insertions, 7 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index 5530ed211f72..ba053d88c8c6 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -223,6 +223,7 @@ struct rq { unsigned long raw_weighted_load; #ifdef CONFIG_SMP unsigned long cpu_load[3]; + unsigned char idle_at_tick; #endif unsigned long long nr_switches; @@ -2943,12 +2944,7 @@ static void run_rebalance_domains(struct softirq_action *h) struct rq *this_rq = cpu_rq(this_cpu); unsigned long interval; struct sched_domain *sd; - /* - * We are idle if there are no processes running. This - * is valid even if we are the idle process (SMT). - */ - enum idle_type idle = !this_rq->nr_running ? - SCHED_IDLE : NOT_IDLE; + enum idle_type idle = this_rq->idle_at_tick ? SCHED_IDLE : NOT_IDLE; /* Earliest time when we have to call run_rebalance_domains again */ unsigned long next_balance = jiffies + 60*HZ; @@ -3218,14 +3214,16 @@ void scheduler_tick(void) unsigned long long now = sched_clock(); struct task_struct *p = current; int cpu = smp_processor_id(); + int idle_at_tick = idle_cpu(cpu); struct rq *rq = cpu_rq(cpu); update_cpu_clock(p, rq, now); - if (p != rq->idle) + if (!idle_at_tick) task_running_tick(rq, p); #ifdef CONFIG_SMP update_load(rq); + rq->idle_at_tick = idle_at_tick; if (time_after_eq(jiffies, rq->next_balance)) raise_softirq(SCHED_SOFTIRQ); #endif |