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Commit ab3b8b1b authored by Srikar Dronamraju's avatar Srikar Dronamraju Committed by Pranav Vashi
Browse files

sched/numa: Modify migrate_swap() to accept additional parameters 



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: default avatarSrikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarRik van Riel <riel@surriel.com>
Acked-by: default avatarMel 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: default avatarIngo Molnar <mingo@kernel.org>
(cherry picked from commit 0ad4e3df)
Change-Id: Ia520fdeb7233d96891af72f80a44b71658951981
[dereference23: Backport to msm-4.14]
Signed-off-by: default avatarAlexander Winkowski <dereference23@outlook.com>
Signed-off-by: default avatarPranav Vashi <neobuddy89@gmail.com>
parent a65fd4e5

kernel/sched/core.c

+4 −3
Original line number Diff line number Diff line
@@ -1334,16 +1334,17 @@ static int migrate_swap_stop(void *data) 
/*

 * 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)

kernel/sched/fair.c

+3 −2
Original line number Diff line number Diff line
@@ -1943,7 +1943,8 @@ 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);
@@ -12985,7 +12986,7 @@ static void walt_rotate_work_func(struct work_struct *work) 
	struct rq *src_rq = cpu_rq(wr->src_cpu), *dst_rq = cpu_rq(wr->dst_cpu);

	unsigned long flags;



	migrate_swap(wr->src_task, wr->dst_task);

	migrate_swap(wr->src_task, wr->dst_task, wr->dst_cpu, wr->src_cpu);



	put_task_struct(wr->src_task);

	put_task_struct(wr->dst_task);

kernel/sched/sched.h

+2 −1
Original line number Diff line number Diff line
@@ -1223,7 +1223,8 @@ 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);

#endif /* CONFIG_NUMA_BALANCING */

extern int migrate_swap(struct task_struct *cur, struct task_struct *p);

extern int migrate_swap(struct task_struct *p, struct task_struct *t,

			int cpu, int scpu);



#ifdef CONFIG_SMP