From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shaohua Li Subject: Re: more dput lock contentions in 2.6.38-rc? Date: Tue, 25 Jan 2011 09:34:18 +0800 Message-ID: <1295919258.1949.973.camel@sli10-conroe> References: <1295915725.1949.967.camel@sli10-conroe> <1295917864.1949.970.camel@sli10-conroe> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: "linux-fsdevel@vger.kernel.org" , lkml , Andrew Morton , Nick Piggin , "Chen, Tim C" To: Nick Piggin Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Tue, 2011-01-25 at 09:26 +0800, Nick Piggin wrote: > On Tue, Jan 25, 2011 at 12:11 PM, Shaohua Li wrote: > > On Tue, 2011-01-25 at 09:04 +0800, Nick Piggin wrote: > >> On Tue, Jan 25, 2011 at 11:35 AM, Shaohua Li wrote: > >> > Hi, > >> > we are testing dbench benchmark and see big drop of 2.6.38-rc compared > >> > to 2.6.37 in several machines with 2 sockets or 4 sockets. We have 12 > >> > disks mount to /mnt/stp/dbenchdata/sd*/ and dbench runs against data of > >> > the disks. According to perf, we saw more lock contentions: > >> > In 2.6.37: 13.00% dbench [kernel.kallsyms] [k] _raw_spin_lock > >> > In 2.6.38-rc: 69.45% dbench [kernel.kallsyms] [k]_raw_spin_lock > >> > - 69.45% dbench [kernel.kallsyms] [k] _raw_spin_lock > >> > - _raw_spin_lock > >> > - 48.41% dput > >> > - 61.17% path_put > >> > - 60.47% do_path_lookup > >> > + 53.18% user_path_at > >> > + 42.13% do_filp_open > >> > + 4.69% user_path_parent > >> > >> What filesystems are mounted on the path? > > ext3 or ext4 > > ext3 or 4 along every step of the path? Are there > any acls loaded, or security policy running? all disks are formated with the same fs, just some machines use ext3 and others ext4. no we don't have acl or security policy. > It may be possible that they're all coming from > /proc/ access. I added trace in dput just after the lock taken. and most files are '/', 'mnt', 'stp'. the percentage of 'proc' is small actually. Thanks, Shaohua