sched/numa: Modify migrate_swap() to accept additional parameters (0ad4e3df) · Commits · 戴 / test

There are checks in migrate_swap_stop() that check if the task/CPU combination is as per migrate_swap_arg before migrating. However atleast one of the two tasks to be swapped by migrate_swap() could have migrated to a completely different CPU before updating the migrate_swap_arg. The new CPU where the task is currently running could be a different node too. If the task has migrated, numa balancer might end up placing a task in a wrong node. Instead of achieving node consolidation, it may end up spreading the load across nodes. To avoid that pass the CPUs as additional parameters. While here, place migrate_swap under CONFIG_NUMA_BALANCING. Running SPECjbb2005 on a 4 node machine and comparing bops/JVM JVMS LAST_PATCH WITH_PATCH %CHANGE 16 25377.3 25226.6 -0.59 1 72287 73326 1.437 Signed-off-by:

Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by:

Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by:

Rik van Riel <riel@surriel.com> Acked-by:

Mel Gorman <mgorman@techsingularity.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1529514181-9842-10-git-send-email-srikar@linux.vnet.ibm.com Signed-off-by:

Ingo Molnar <mingo@kernel.org>

kernel/sched/core.c

+6 −3

Original line number	Diff line number	Diff line
		@@ -1176,6 +1176,7 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
		__set_task_cpu(p, new_cpu);
		}

		#ifdef CONFIG_NUMA_BALANCING
		static void __migrate_swap_task(struct task_struct *p, int cpu)
		{
		if (task_on_rq_queued(p)) {
		@@ -1257,16 +1258,17 @@ unlock:
		/*
		* Cross migrate two tasks
		*/
		int migrate_swap(struct task_struct cur, struct task_struct p)
		int migrate_swap(struct task_struct cur, struct task_struct p,
		int target_cpu, int curr_cpu)
		{
		struct migration_swap_arg arg;
		int ret = -EINVAL;

		arg = (struct migration_swap_arg){
		.src_task = cur,
		.src_cpu = task_cpu(cur),
		.src_cpu = curr_cpu,
		.dst_task = p,
		.dst_cpu = task_cpu(p),
		.dst_cpu = target_cpu,
		};

		if (arg.src_cpu == arg.dst_cpu)
		@@ -1291,6 +1293,7 @@ int migrate_swap(struct task_struct cur, struct task_struct p)
		out:
		return ret;
		}
		#endif /* CONFIG_NUMA_BALANCING */

		/*
		* wait_task_inactive - wait for a thread to unschedule.

kernel/sched/fair.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -1848,7 +1848,8 @@ static int task_numa_migrate(struct task_struct *p)
		return ret;
		}

		ret = migrate_swap(p, env.best_task);
		ret = migrate_swap(p, env.best_task, env.best_cpu, env.src_cpu);

		if (ret != 0)
		trace_sched_stick_numa(p, env.src_cpu, task_cpu(env.best_task));
		put_task_struct(env.best_task);

kernel/sched/sched.h

+2 −1

Original line number	Diff line number	Diff line
		@@ -1099,7 +1099,8 @@ enum numa_faults_stats {
		};
		extern void sched_setnuma(struct task_struct *p, int node);
		extern int migrate_task_to(struct task_struct *p, int cpu);
		extern int migrate_swap(struct task_struct , struct task_struct );
		extern int migrate_swap(struct task_struct p, struct task_struct t,
		int cpu, int scpu);
		extern void init_numa_balancing(unsigned long clone_flags, struct task_struct *p);
		#else
		static inline void

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