diff options
| author | Andrew Theurer <habanero@us.ibm.com> | 2005-01-07 21:44:22 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@evo.osdl.org> | 2005-01-07 21:44:22 -0800 |
| commit | 6a991f77ef744253cd108d9442eeb85c734cb489 (patch) | |
| tree | edf0b4463bd33db8c98cd4fb9f9343cff7d6e82b /kernel | |
| parent | f16c759b750250439dd769183d2a41174bb18519 (diff) | |
| download | history-6a991f77ef744253cd108d9442eeb85c734cb489.tar.gz | |
[PATCH] sched: can_migrate exception for idle cpus
Fix can_migrate to allow aggressive steal for idle cpus. This -was- in
mainline, but I believe sched_domains kind of blasted it outta there. IMO,
it's a no brainer for an idle cpu (with all that cache going to waste) to
be granted to steal a task. The one enhancement I have made was to make
sure the whole cpu was idle.
Signed-off-by: <habanero@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched.c | 50 |
1 files changed, 27 insertions, 23 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index a017d690dbfa47..d66bdb9bb2784a 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -455,6 +455,22 @@ static inline void rq_unlock(runqueue_t *rq) spin_unlock_irq(&rq->lock); } +#ifdef CONFIG_SCHED_SMT +static int cpu_and_siblings_are_idle(int cpu) +{ + int sib; + for_each_cpu_mask(sib, cpu_sibling_map[cpu]) { + if (idle_cpu(sib)) + continue; + return 0; + } + + return 1; +} +#else +#define cpu_and_siblings_are_idle(A) idle_cpu(A) +#endif + #ifdef CONFIG_SCHEDSTATS /* * Called when a process is dequeued from the active array and given @@ -1668,13 +1684,18 @@ int can_migrate_task(task_t *p, runqueue_t *rq, int this_cpu, if (!cpu_isset(this_cpu, p->cpus_allowed)) return 0; - /* Aggressive migration if we've failed balancing */ - if (idle == NEWLY_IDLE || - sd->nr_balance_failed < sd->cache_nice_tries) { - if (task_hot(p, rq->timestamp_last_tick, sd)) - return 0; - } + /* + * Aggressive migration if: + * 1) the [whole] cpu is idle, or + * 2) too many balance attempts have failed. + */ + if (cpu_and_siblings_are_idle(this_cpu) || \ + sd->nr_balance_failed > sd->cache_nice_tries) + return 1; + + if (task_hot(p, rq->timestamp_last_tick, sd)) + return 0; return 1; } @@ -2089,23 +2110,6 @@ static inline void idle_balance(int this_cpu, runqueue_t *this_rq) } } -#ifdef CONFIG_SCHED_SMT -static int cpu_and_siblings_are_idle(int cpu) -{ - int sib; - for_each_cpu_mask(sib, cpu_sibling_map[cpu]) { - if (idle_cpu(sib)) - continue; - return 0; - } - - return 1; -} -#else -#define cpu_and_siblings_are_idle(A) idle_cpu(A) -#endif - - /* * active_load_balance is run by migration threads. It pushes running tasks * off the busiest CPU onto idle CPUs. It requires at least 1 task to be |