linux-kernel - Re: [PATCH 3/4] memcg: get rid of percpu_charge

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Message-Id: <20110722084927.96b0aa86.kamezawa.hiroyu@jp.fujitsu.com>
Date:	Fri, 22 Jul 2011 08:49:27 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Michal Hocko <mhocko@...e.cz>
Cc:	linux-mm@...ck.org, Balbir Singh <bsingharora@...il.com>,
	Daisuke Nishimura <nishimura@....nes.nec.co.jp>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] memcg: get rid of percpu_charge_mutex lock

On Thu, 21 Jul 2011 14:42:23 +0200
Michal Hocko <mhocko@...e.cz> wrote:

> On Thu 21-07-11 13:47:04, Michal Hocko wrote:
> > On Thu 21-07-11 19:30:51, KAMEZAWA Hiroyuki wrote:
> > > On Thu, 21 Jul 2011 09:58:24 +0200
> > > Michal Hocko <mhocko@...e.cz> wrote:
> [...]
> > > > --- a/mm/memcontrol.c
> > > > +++ b/mm/memcontrol.c
> > > > @@ -2166,7 +2165,8 @@ static void drain_all_stock(struct mem_cgroup *root_mem, bool sync)
> > > >  
> > > >  	for_each_online_cpu(cpu) {
> > > >  		struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu);
> > > > -		if (test_bit(FLUSHING_CACHED_CHARGE, &stock->flags))
> > > > +		if (root_mem == stock->cached &&
> > > > +				test_bit(FLUSHING_CACHED_CHARGE, &stock->flags))
> > > >  			flush_work(&stock->work);
> > > 
> > > Doesn't this new check handle hierarchy ?
> > > css_is_ancestor() will be required if you do this check.
> > 
> > Yes you are right. Will fix it. I will add a helper for the check.
> 
> Here is the patch with the helper. The above will then read 
> 	if (mem_cgroup_same_or_subtree(root_mem, stock->cached))
> 
> ---
> From b963a9f4dac61044daac49700f84b7819d7c2f53 Mon Sep 17 00:00:00 2001
> From: Michal Hocko <mhocko@...e.cz>
> Date: Thu, 21 Jul 2011 13:54:13 +0200
> Subject: [PATCH] memcg: add mem_cgroup_same_or_subtree helper
> 
> We are checking whether a given two groups are same or at least in the
> same subtree of a hierarchy at several places. Let's make a helper for
> it to make code easier to read.
> 
> Signed-off-by: Michal Hocko <mhocko@...e.cz>

Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>


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