sched/numa: Retry placement more frequently when misplaced (5085e2a3) · Commits · 戴 / test

When tasks have not converged on their preferred nodes yet, we want to retry fairly often, to make sure we do not migrate a task's memory to an undesirable location, only to have to move it again later. This patch reduces the interval at which migration is retried, when the task's numa_scan_period is small. Signed-off-by:

Rik van Riel <riel@redhat.com> Tested-by:

Vinod Chegu <chegu_vinod@hp.com> Acked-by:

Mel Gorman <mgorman@suse.de> Signed-off-by:

Peter Zijlstra <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1397235629-16328-3-git-send-email-riel@redhat.com Signed-off-by:

Ingo Molnar <mingo@kernel.org>

kernel/sched/fair.c

+4 −1

Original line number	Original line	Diff line number	Diff line
	@@ -1326,12 +1326,15 @@ static int task_numa_migrate(struct task_struct *p)
	/* Attempt to migrate a task to a CPU on the preferred node. */		/* Attempt to migrate a task to a CPU on the preferred node. */
	static void numa_migrate_preferred(struct task_struct *p)		static void numa_migrate_preferred(struct task_struct *p)
	{		{
			unsigned long interval = HZ;

	/* This task has no NUMA fault statistics yet */		/* This task has no NUMA fault statistics yet */
	if (unlikely(p->numa_preferred_nid == -1 \|\| !p->numa_faults_memory))		if (unlikely(p->numa_preferred_nid == -1 \|\| !p->numa_faults_memory))
	return;		return;

	/* Periodically retry migrating the task to the preferred node */		/* Periodically retry migrating the task to the preferred node */
	p->numa_migrate_retry = jiffies + HZ;		interval = min(interval, msecs_to_jiffies(p->numa_scan_period) / 16);
			p->numa_migrate_retry = jiffies + interval;

	/* Success if task is already running on preferred CPU */		/* Success if task is already running on preferred CPU */
	if (task_node(p) == p->numa_preferred_nid)		if (task_node(p) == p->numa_preferred_nid)

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