Date: Thu, 25 Feb 2010 15:34:44 +0100
From: Andrea Righi <arighi@develer.com>
To: David Rientjes <rientjes@google.com>
Cc: Vivek Goyal <vgoyal@redhat.com>, Balbir Singh <balbir@linux.vnet.ibm.com>,
       KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
       Suleiman Souhlal <suleiman@google.com>,
       Andrew Morton <akpm@linux-foundation.org>,
       containers@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] memcg: dirty pages instrumentation
Message-ID: <20100225143444.GB3964@linux>
References: <1266765525-30890-1-git-send-email-arighi@develer.com>
 <1266765525-30890-3-git-send-email-arighi@develer.com>
 <20100222165215.GA3096@redhat.com>
 <20100223094040.GC1882@linux>
 <20100223195606.GD11930@redhat.com>
 <alpine.DEB.2.00.1002231419450.8693@chino.kir.corp.google.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <alpine.DEB.2.00.1002231419450.8693@chino.kir.corp.google.com>
User-Agent: Mutt/1.5.20 (2009-06-14)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1658
Lines: 34

On Tue, Feb 23, 2010 at 02:22:12PM -0800, David Rientjes wrote:
> On Tue, 23 Feb 2010, Vivek Goyal wrote:
> 
> > > > Because you have modified dirtyable_memory() and made it per cgroup, I
> > > > think it automatically takes care of the cases of per cgroup dirty ratio,
> > > > I mentioned in my previous mail. So we will use system wide dirty ratio
> > > > to calculate the allowed dirty pages in this cgroup (dirty_ratio *
> > > > available_memory()) and if this cgroup wrote too many pages start
> > > > writeout? 
> > > 
> > > OK, if I've understood well, you're proposing to use per-cgroup
> > > dirty_ratio interface and do something like:
> > 
> > I think we can use system wide dirty_ratio for per cgroup (instead of
> > providing configurable dirty_ratio for each cgroup where each memory
> > cgroup can have different dirty ratio. Can't think of a use case
> > immediately).
> 
> I think each memcg should have both dirty_bytes and dirty_ratio, 
> dirty_bytes defaults to 0 (disabled) while dirty_ratio is inherited from 
> the global vm_dirty_ratio.  Changing vm_dirty_ratio would not change 
> memcgs already using their own dirty_ratio, but new memcgs would get the 
> new value by default.  The ratio would act over the amount of available 
> memory to the cgroup as though it were its own "virtual system" operating 
> with a subset of the system's RAM and the same global ratio.

Agreed.

-Andrea
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/