From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx194.postini.com [74.125.245.194]) by kanga.kvack.org (Postfix) with SMTP id 4DCAB6B005D for ; Wed, 15 Aug 2012 10:36:39 -0400 (EDT) Received: from /spool/local by e7.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 15 Aug 2012 10:36:37 -0400 Received: from d01relay03.pok.ibm.com (d01relay03.pok.ibm.com [9.56.227.235]) by d01dlp03.pok.ibm.com (Postfix) with ESMTP id C3795C90928 for ; Wed, 15 Aug 2012 10:24:50 -0400 (EDT) Received: from d01av02.pok.ibm.com (d01av02.pok.ibm.com [9.56.224.216]) by d01relay03.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q7FEOnH1084070 for ; Wed, 15 Aug 2012 10:24:50 -0400 Received: from d01av02.pok.ibm.com (loopback [127.0.0.1]) by d01av02.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q7FEOmew029733 for ; Wed, 15 Aug 2012 11:24:48 -0300 Message-ID: <502BB125.7030607@linux.vnet.ibm.com> Date: Wed, 15 Aug 2012 09:24:37 -0500 From: Seth Jennings MIME-Version: 1.0 Subject: Re: [PATCH 0/4] promote zcache from staging References: <1343413117-1989-1-git-send-email-sjenning@linux.vnet.ibm.com> <5021795A.5000509@linux.vnet.ibm.com> <5024067F.3010602@linux.vnet.ibm.com> <2e9ccb4f-1339-4c26-88dd-ea294b022127@default> <50254F69.2000409@linux.vnet.ibm.com> <20120815093828.GB2865@phenom.dumpdata.com> In-Reply-To: <20120815093828.GB2865@phenom.dumpdata.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Konrad Rzeszutek Wilk Cc: Dan Magenheimer , Greg Kroah-Hartman , Andrew Morton , Nitin Gupta , Minchan Kim , Robert Jennings , linux-mm@kvack.org, linux-kernel@vger.kernel.org, devel@driverdev.osuosl.org, Kurt Hackel On 08/15/2012 04:38 AM, Konrad Rzeszutek Wilk wrote: > On Fri, Aug 10, 2012 at 01:14:01PM -0500, Seth Jennings wrote: >> On 08/09/2012 03:20 PM, Dan Magenheimer wrote >>> I also wonder if you have anything else unusual in your >>> test setup, such as a fast swap disk (mine is a partition >>> on the same rotating disk as source and target of the kernel build, >>> the default install for a RHEL6 system)? >> >> I'm using a normal SATA HDD with two partitions, one for >> swap and the other an ext3 filesystem with the kernel source. >> >>> Or have you disabled cleancache? >> >> Yes, I _did_ disable cleancache. I could see where having >> cleancache enabled could explain the difference in results. > > Why did you disable the cleancache? Having both (cleancache > to compress fs data) and frontswap (to compress swap data) is the > goal - while you turned one of its sources off. I excluded cleancache to reduce interference/noise from the benchmarking results. For this particular workload, cleancache doesn't make a lot of sense since it will steal pages that could otherwise be used for storing frontswap pages to prevent swapin/swapout I/O. In a test run with both enabled, I found that it didn't make much difference under moderate to extreme memory pressure. Both resulted in about 55% I/O reduction. However, on light memory pressure with 8 and 12 threads, it lowered the I/O reduction ability of zcache to roughly 0 compared to ~20% I/O reduction without cleancache. In short, cleancache only had the power to harm in this case, so I didn't enable it. Seth -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org