Commit 1489ebad authored by KAMEZAWA Hiroyuki's avatar KAMEZAWA Hiroyuki Committed by Linus Torvalds
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memcg: cpu hotplug aware quick acount_move detection 



An event counter MEM_CGROUP_ON_MOVE is used for quick check whether file
stat update can be done in async manner or not.  Now, it use percpu
counter and for_each_possible_cpu to update.

This patch replaces for_each_possible_cpu to for_each_online_cpu and adds
necessary synchronization logic at CPU HOTPLUG.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 711d3d2c

mm/memcontrol.c

+30 −7
Original line number Diff line number Diff line
@@ -1132,11 +1132,14 @@ static unsigned int get_swappiness(struct mem_cgroup *memcg) 
static void mem_cgroup_start_move(struct mem_cgroup *mem)

{

	int cpu;

	/* Because this is for moving account, reuse mc.lock */

	spin_lock(&mc.lock);

	for_each_possible_cpu(cpu)



	get_online_cpus();

	spin_lock(&mem->pcp_counter_lock);

	for_each_online_cpu(cpu)

		per_cpu(mem->stat->count[MEM_CGROUP_ON_MOVE], cpu) += 1;

	spin_unlock(&mc.lock);

	mem->nocpu_base.count[MEM_CGROUP_ON_MOVE] += 1;

	spin_unlock(&mem->pcp_counter_lock);

	put_online_cpus();



	synchronize_rcu();

}
@@ -1147,10 +1150,13 @@ static void mem_cgroup_end_move(struct mem_cgroup *mem) 


	if (!mem)

		return;

	spin_lock(&mc.lock);

	for_each_possible_cpu(cpu)

	get_online_cpus();

	spin_lock(&mem->pcp_counter_lock);

	for_each_online_cpu(cpu)

		per_cpu(mem->stat->count[MEM_CGROUP_ON_MOVE], cpu) -= 1;

	spin_unlock(&mc.lock);

	mem->nocpu_base.count[MEM_CGROUP_ON_MOVE] -= 1;

	spin_unlock(&mem->pcp_counter_lock);

	put_online_cpus();

}

/*

 * 2 routines for checking "mem" is under move_account() or not.
@@ -1751,6 +1757,17 @@ static void mem_cgroup_drain_pcp_counter(struct mem_cgroup *mem, int cpu) 
		per_cpu(mem->stat->count[i], cpu) = 0;

		mem->nocpu_base.count[i] += x;

	}

	/* need to clear ON_MOVE value, works as a kind of lock. */

	per_cpu(mem->stat->count[MEM_CGROUP_ON_MOVE], cpu) = 0;

	spin_unlock(&mem->pcp_counter_lock);

}



static void synchronize_mem_cgroup_on_move(struct mem_cgroup *mem, int cpu)

{

	int idx = MEM_CGROUP_ON_MOVE;



	spin_lock(&mem->pcp_counter_lock);

	per_cpu(mem->stat->count[idx], cpu) = mem->nocpu_base.count[idx];

	spin_unlock(&mem->pcp_counter_lock);

}
@@ -1762,6 +1779,12 @@ static int __cpuinit memcg_cpu_hotplug_callback(struct notifier_block *nb, 
	struct memcg_stock_pcp *stock;

	struct mem_cgroup *iter;



	if ((action == CPU_ONLINE)) {

		for_each_mem_cgroup_all(iter)

			synchronize_mem_cgroup_on_move(iter, cpu);

		return NOTIFY_OK;

	}



	if ((action != CPU_DEAD) || action != CPU_DEAD_FROZEN)

		return NOTIFY_OK;

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