Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=bdecea3a9282d529b54954f3f1e59877629baba1
Commit: bdecea3a9282d529b54954f3f1e59877629baba1
Parent: 2bd7e20e0d24325b0799544bc8105cc57cc8e2aa
Author: Siddha, Suresh B <[EMAIL PROTECTED]>
AuthorDate: Tue May 8 00:32:48 2007 -0700
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Tue May 8 11:15:17 2007 -0700
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.
[EMAIL PROTECTED]: Fix reverse idle at tick logic]
Signed-off-by: Suresh Siddha <[EMAIL PROTECTED]>
Acked-by: Ingo Molnar <[EMAIL PROTECTED]>
Cc: Thomas Gleixner <[EMAIL PROTECTED]>
Cc: Nick Piggin <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
kernel/sched.c | 12 +++++-------
1 files changed, 5 insertions(+), 7 deletions(-)
diff --git a/kernel/sched.c b/kernel/sched.c
index 5530ed2..ba053d8 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
-
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