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author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2009-11-12 15:55:28 +0100 |
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committer | Ingo Molnar <mingo@elte.hu> | 2009-11-13 10:09:58 +0100 |
commit | a50bde5130f65733142b32975616427d0ea50856 (patch) | |
tree | c2bf0c04fbebfa0f3d6ae8b709f754d5fce4b831 /kernel/sched_fair.c | |
parent | 761b1d26df542fd5eb348837351e4d2f3bc7bffe (diff) | |
download | linux-stable-a50bde5130f65733142b32975616427d0ea50856.tar.gz linux-stable-a50bde5130f65733142b32975616427d0ea50856.tar.bz2 linux-stable-a50bde5130f65733142b32975616427d0ea50856.zip |
sched: Cleanup select_task_rq_fair()
Clean up the new affine to idle sibling bits while trying to
grok them. Should not have any function differences.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <20091112145610.832503781@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/sched_fair.c')
-rw-r--r-- | kernel/sched_fair.c | 73 |
1 files changed, 51 insertions, 22 deletions
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index e4d4483fd617..a32df1524746 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -1319,6 +1319,41 @@ find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu) } /* + * Try and locate an idle CPU in the sched_domain. + */ +static int +select_idle_sibling(struct task_struct *p, struct sched_domain *sd, int target) +{ + int cpu = smp_processor_id(); + int prev_cpu = task_cpu(p); + int i; + + /* + * If this domain spans both cpu and prev_cpu (see the SD_WAKE_AFFINE + * test in select_task_rq_fair) and the prev_cpu is idle then that's + * always a better target than the current cpu. + */ + if (target == cpu) { + if (!cpu_rq(prev_cpu)->cfs.nr_running) + target = prev_cpu; + } + + /* + * Otherwise, iterate the domain and find an elegible idle cpu. + */ + if (target == -1 || target == cpu) { + for_each_cpu_and(i, sched_domain_span(sd), &p->cpus_allowed) { + if (!cpu_rq(i)->cfs.nr_running) { + target = i; + break; + } + } + } + + return target; +} + +/* * sched_balance_self: balance the current task (running on cpu) in domains * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and * SD_BALANCE_EXEC. @@ -1373,36 +1408,30 @@ static int select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flag } if (want_affine && (tmp->flags & SD_WAKE_AFFINE)) { - int candidate = -1, i; + int target = -1; + /* + * If both cpu and prev_cpu are part of this domain, + * cpu is a valid SD_WAKE_AFFINE target. + */ if (cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) - candidate = cpu; + target = cpu; /* - * Check for an idle shared cache. + * If there's an idle sibling in this domain, make that + * the wake_affine target instead of the current cpu. + * + * XXX: should we possibly do this outside of + * WAKE_AFFINE, in case the shared cache domain is + * smaller than the WAKE_AFFINE domain? */ - if (tmp->flags & SD_PREFER_SIBLING) { - if (candidate == cpu) { - if (!cpu_rq(prev_cpu)->cfs.nr_running) - candidate = prev_cpu; - } - - if (candidate == -1 || candidate == cpu) { - for_each_cpu(i, sched_domain_span(tmp)) { - if (!cpumask_test_cpu(i, &p->cpus_allowed)) - continue; - if (!cpu_rq(i)->cfs.nr_running) { - candidate = i; - break; - } - } - } - } + if (tmp->flags & SD_PREFER_SIBLING) + target = select_idle_sibling(p, tmp, target); - if (candidate >= 0) { + if (target >= 0) { affine_sd = tmp; want_affine = 0; - cpu = candidate; + cpu = target; } } |