From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754093AbZICCYW (ORCPT ); Wed, 2 Sep 2009 22:24:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753499AbZICCYW (ORCPT ); Wed, 2 Sep 2009 22:24:22 -0400 Received: from mail.valinux.co.jp ([210.128.90.3]:33232 "EHLO mail.valinux.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753261AbZICCYV convert rfc822-to-8bit (ORCPT ); Wed, 2 Sep 2009 22:24:21 -0400 Date: Thu, 03 Sep 2009 11:24:23 +0900 (JST) Message-Id: <20090903.112423.226782505.ryov@valinux.co.jp> To: vgoyal@redhat.com Cc: nauman@google.com, riel@redhat.com, linux-kernel@vger.kernel.org, jens.axboe@oracle.com, containers@lists.linux-foundation.org, dm-devel@redhat.com, dpshah@google.com, lizf@cn.fujitsu.com, mikew@google.com, fchecconi@gmail.com, paolo.valente@unimore.it, fernando@oss.ntt.co.jp, s-uchida@ap.jp.nec.com, taka@valinux.co.jp, guijianfeng@cn.fujitsu.com, jmoyer@redhat.com, dhaval@linux.vnet.ibm.com, balbir@linux.vnet.ibm.com, righi.andrea@gmail.com, m-ikeda@ds.jp.nec.com, agk@redhat.com, akpm@linux-foundation.org, peterz@infradead.org, jmarchan@redhat.com, torvalds@linux-foundation.org, mingo@elte.hu Subject: Re: [PATCH 18/23] io-controller: blkio_cgroup patches from Ryo to track async bios. From: Ryo Tsuruta In-Reply-To: <20090902135821.GB5012@redhat.com> References: <20090901141142.GA13709@redhat.com> <20090902.185251.193693849.ryov@valinux.co.jp> <20090902135821.GB5012@redhat.com> X-Mailer: Mew version 5.2.52 on Emacs 22.1 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=iso-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Vivek, Vivek Goyal wrote: > > > > > > - Somebody also gave an example where there is a memory hogging process and > > > > > >  possibly pushes out some processes to swap. It does not sound fair to > > > > > >  charge those proccess for that swap writeout. These processes never > > > > > >  requested swap IO. > > > > > > > > I think that swap writeouts should be charged to the memory hogging > > > > process, because the process consumes more resources and it should get > > > > a penalty. > > > > > > > > > > A process requesting memory gets IO penalty? IMHO, swapping is a kernel > > > mechanism and kernel's way of providing extended RAM. If we want to solve > > > the issue of memory hogging by a process then right way to solve is to use > > > memory controller and not by charging the process for IO activity. > > > Instead, proabably a more suitable way is to charge swap activity to root > > > group (where by default all the kernel related activity goes). > > > > No. In the current blkio-cgroup, a process which uses a large amount > > of memory gets penalty, not a memory requester. > > > > At ioband level you just get to see bio and page. How do you decide wheter > this bio is being issued by a process which is a memory hog? > > In fact requester of memory could be anybody. It could be memory hog or a > different process. So are you saying that you got a mechanism where you > can detect that a process is memory hog and charge swap activity to it. > IOW, if there are two processes A and B and assume A is the memory hog and > then B requests for memory which triggers lot of swap IO, then you can > charge all that IO to memory hog A? When an annoymou page is allocated, blkio-cgroup sets an ID to the page. And then when the page is going to swap out, dm-ioband can know who the owner of the page is by retrieving ID from the page. In the above case, since the pages of the process A are swapped-out, dm-ioband charges swap IO to the process A. > Can you please point me to the relevant code in dm-ioband? > > IMHO, to keep things simple, all swapping activity should be charged to > root group and be considered as kernel activity and user space not be > charged for that. Thanks, Ryo Tsuruta