sched/numa: Count pages on active node as local (792568ec) · Commits · 戴 / test

The NUMA code is smart enough to distribute the memory of workloads that span multiple NUMA nodes across those NUMA nodes. However, it still has a pretty high scan rate for such workloads, because any memory that is left on a node other than the node of the CPU that faulted on the memory is counted as non-local, which causes the scan rate to go up. Counting the memory on any node where the task's numa group is actively running as local, allows the scan rate to slow down once the application is settled in. This should reduce the overhead of the automatic NUMA placement code, when a workload spans multiple NUMA nodes. 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/1397235629-16328-2-git-send-email-riel@redhat.com Signed-off-by:

Ingo Molnar <mingo@kernel.org>

kernel/sched/fair.c

+13 −1

Original line number	Diff line number	Diff line
		@@ -1738,6 +1738,7 @@ void task_numa_fault(int last_cpupid, int mem_node, int pages, int flags)
		struct task_struct *p = current;
		bool migrated = flags & TNF_MIGRATED;
		int cpu_node = task_node(current);
		int local = !!(flags & TNF_FAULT_LOCAL);
		int priv;

		if (!numabalancing_enabled)
		@@ -1786,6 +1787,17 @@ void task_numa_fault(int last_cpupid, int mem_node, int pages, int flags)
		task_numa_group(p, last_cpupid, flags, &priv);
		}

		/*
		* If a workload spans multiple NUMA nodes, a shared fault that
		* occurs wholly within the set of nodes that the workload is
		* actively using should be counted as local. This allows the
		* scan rate to slow down when a workload has settled down.
		*/
		if (!priv && !local && p->numa_group &&
		node_isset(cpu_node, p->numa_group->active_nodes) &&
		node_isset(mem_node, p->numa_group->active_nodes))
		local = 1;

		task_numa_placement(p);

		/*
		@@ -1800,7 +1812,7 @@ void task_numa_fault(int last_cpupid, int mem_node, int pages, int flags)

		p->numa_faults_buffer_memory[task_faults_idx(mem_node, priv)] += pages;
		p->numa_faults_buffer_cpu[task_faults_idx(cpu_node, priv)] += pages;
		p->numa_faults_locality[!!(flags & TNF_FAULT_LOCAL)] += pages;
		p->numa_faults_locality[local] += pages;
		}

		static void reset_ptenuma_scan(struct task_struct *p)

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