From: Eric Sandeen Subject: Re: [PATCH] quota: remove dqptr_sem for scalability Date: Thu, 22 May 2014 23:02:28 -0500 Message-ID: <537EC854.1060605@redhat.com> References: <537DD5BA.1050105@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=GB2312 Content-Transfer-Encoding: 7bit Cc: yawei.niu@intel.com, andreas.dilger@intel.com, jack@suse.cz, lai.siyao@intel.com To: Niu Yawei , linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org Return-path: In-Reply-To: <537DD5BA.1050105@gmail.com> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On 5/22/14, 5:47 AM, Niu Yawei wrote: > There are several global locks in the VFS quota code which hurts > performance a lot when quota accounting enabled, dqptr_sem is the major one. > > This patch tries to make the VFS quota code scalable with minimal changes. > > Following tests (mdtest & dbench) were running over ext4 fs in a > centos6.5 vm (8 cpus, 4G mem, kenrel: 3.15.0-rc5+), and the result shows > the patch relieved the lock congestion a lot. > Just noticed this patch - FWIW, Lustre has a "quota-replace-dqptr-sem-sles11sp2.patch" that they apply: http://git.whamcloud.com/?p=fs/lustre-release.git;a=blob;f=lustre/kernel_patches/patches/quota-replace-dqptr-sem-sles11sp2.patch;h=c880dac83473f48cac96dc467ea76f64a74fe5dd;hb=HEAD which might be interesting if you're looking at this. (Or maybe it's doing the same thing; TBH I have not looked at either patch, I just remembered that it existed...) -eric