On Mon, Jan 23, 2012 at 8:47 PM, KAMEZAWA Hiroyuki
[off-list ref] wrote:

On Mon, 23 Jan 2012 14:02:48 -0800
Ying Han [off-list ref] wrote:

quoted

On Fri, Jan 13, 2012 at 12:40 AM, KAMEZAWA Hiroyuki
[off-list ref] wrote:

quoted

From 1008e84d94245b1e7c4d237802ff68ff00757736 Mon Sep 17 00:00:00 2001
From: KAMEZAWA Hiroyuki <redacted>
Date: Thu, 12 Jan 2012 15:53:24 +0900
Subject: [PATCH 3/7] memcg: remove PCG_MOVE_LOCK flag from pc->flags.

PCG_MOVE_LOCK bit is used for bit spinlock for avoiding race between
memcg's account moving and page state statistics updates.

Considering page-statistics update, very hot path, this lock is
taken only when someone is moving account (or PageTransHuge())
And, now, all moving-account between memcgroups (by task-move)
are serialized.

This might be a side question, can you clarify the serialization here?
Does it mean that we only allow one task-move at a time system-wide?

current implementation has that limit by mutex.

ah, thanks. that is the cgroup_mutex lock which serializes
mem_cgroup_move_charge() from move task.

--Ying

Thanks,
-Kame

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