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: KAMEZAWA 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 31a1d3b..52840ad 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1132,11 +1132,14 @@
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 @@
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 @@
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 @@
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;