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sched/numa: Resist moving tasks towards nodes with fewer hinting faults 

Just as "sched: Favour moving tasks towards the preferred node" favours
moving tasks towards nodes with a higher number of recorded NUMA hinting
faults, this patch resists moving tasks towards nodes with lower faults.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1381141781-10992-24-git-send-email-mgorman@suse.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Mel Gorman 2013-10-07 11:29:01 +01:00 committed by Ingo Molnar
parent 3a7053b322
commit 7a0f308337
2 changed files with 41 additions and 0 deletions
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33
kernel/sched/fair.c
View File

@ -4107,12 +4107,43 @@ static bool migrate_improves_locality(struct task_struct *p, struct lb_env *env)
return false;
}
static bool migrate_degrades_locality(struct task_struct *p, struct lb_env *env)
{
int src_nid, dst_nid;
if (!sched_feat(NUMA) || !sched_feat(NUMA_RESIST_LOWER))
return false;
if (!p->numa_faults || !(env->sd->flags & SD_NUMA))
return false;
src_nid = cpu_to_node(env->src_cpu);
dst_nid = cpu_to_node(env->dst_cpu);
if (src_nid == dst_nid ||
p->numa_migrate_seq >= sysctl_numa_balancing_settle_count)
return false;
if (p->numa_faults[dst_nid] < p->numa_faults[src_nid])
return true;
return false;
}
#else
static inline bool migrate_improves_locality(struct task_struct *p,
struct lb_env *env)
{
return false;
}
static inline bool migrate_degrades_locality(struct task_struct *p,
struct lb_env *env)
{
return false;
}
#endif
/*
@ -4177,6 +4208,8 @@ int can_migrate_task(struct task_struct *p, struct lb_env *env)
* 3) too many balance attempts have failed.
*/
tsk_cache_hot = task_hot(p, rq_clock_task(env->src_rq), env->sd);
if (!tsk_cache_hot)
tsk_cache_hot = migrate_degrades_locality(p, env);
if (migrate_improves_locality(p, env)) {
#ifdef CONFIG_SCHEDSTATS

8
kernel/sched/features.h
View File

@ -74,4 +74,12 @@ SCHED_FEAT(NUMA, false)
* balancing.
*/
SCHED_FEAT(NUMA_FAVOUR_HIGHER, true)
/*
* NUMA_RESIST_LOWER will resist moving tasks towards nodes where a
* lower number of hinting faults have been recorded. As this has
* the potential to prevent a task ever migrating to a new node
* due to CPU overload it is disabled by default.
*/
SCHED_FEAT(NUMA_RESIST_LOWER, false)
#endif