From mboxrd@z Thu Jan 1 00:00:00 1970 From: Waiman Long Subject: Re: [PATCH] dcache: Translating dentry into pathname without taking rename_lock Date: Wed, 04 Sep 2013 22:04:31 -0400 Message-ID: <5227E6AF.2040603@hp.com> References: <1378321523-40893-1-git-send-email-Waiman.Long@hp.com> <52278970.2080803@hp.com> <21031.39606.16374.72229@quad.stoffel.home> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Alexander Viro , Linus Torvalds , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, "Chandramouleeswaran, Aswin" , "Norton, Scott J" To: John Stoffel Return-path: In-Reply-To: <21031.39606.16374.72229@quad.stoffel.home> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On 09/04/2013 04:40 PM, John Stoffel wrote: >>>>>> "Waiman" == Waiman Long writes: > Waiman> In term of AIM7 performance, this patch has a performance boost of > Waiman> about 6-7% on top of Linus' lockref patch on a 8-socket 80-core DL980. > > Waiman> User Range | 10-100 | 200-10000 | 1100-2000 | > Waiman> Mean JPM w/o patch | 4,365,114 | 7,211,115 | 6,964,439 | > Waiman> Mean JPM with patch | 3,872,850 | 7,655,958 | 7,422,598 | > Waiman> % Change | -11.3% | +6.2% | +6.6% | > > This -11% impact is worisome to me, because at smaller numbers of > users, I would still expect the performance to go up. So why the big > drop? > > Also, how is the impact of these changes on smaller 1 socket, 4 core > systems? Just because it helps a couple of big boxes, doesn't mean it > won't hurt the more common small case. > > John I don't believe the patch will make it slower with less user. It is more a result of run-to-run variation. The short workload typically completed in a very short time. In the 10-100 user range, the completion times range from 0.02-0.11s. With a higher user count, it needs several seconds to run and hence the results are more reliable. Longman