From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx195.postini.com [74.125.245.195]) by kanga.kvack.org (Postfix) with SMTP id E0B5A6B005D for ; Wed, 11 Jul 2012 10:00:50 -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, 11 Jul 2012 10:00:49 -0400 Received: from d01relay05.pok.ibm.com (d01relay05.pok.ibm.com [9.56.227.237]) by d01dlp02.pok.ibm.com (Postfix) with ESMTP id 430F46E8088 for ; Wed, 11 Jul 2012 10:00:45 -0400 (EDT) Received: from d01av01.pok.ibm.com (d01av01.pok.ibm.com [9.56.224.215]) by d01relay05.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q6BE0hUL355168 for ; Wed, 11 Jul 2012 10:00:43 -0400 Received: from d01av01.pok.ibm.com (loopback [127.0.0.1]) by d01av01.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q6BJVZgZ004832 for ; Wed, 11 Jul 2012 15:31:36 -0400 Message-ID: <4FFD86FE.1090307@linux.vnet.ibm.com> Date: Wed, 11 Jul 2012 09:00:30 -0500 From: Seth Jennings MIME-Version: 1.0 Subject: Re: [PATCH 0/4] zsmalloc improvements References: <1341263752-10210-1-git-send-email-sjenning@linux.vnet.ibm.com> <4FFD2524.2050300@kernel.org> In-Reply-To: <4FFD2524.2050300@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim Cc: Greg Kroah-Hartman , Andrew Morton , Dan Magenheimer , Konrad Rzeszutek Wilk , Nitin Gupta , Robert Jennings , linux-mm@kvack.org, devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org On 07/11/2012 02:03 AM, Minchan Kim wrote: > On 07/03/2012 06:15 AM, Seth Jennings wrote: >> zsmapbench measures the copy-based mapping at ~560 cycles for a >> map/unmap operation on spanned object for both KVM guest and bare-metal, >> while the page table mapping was ~1500 cycles on a VM and ~760 cycles >> bare-metal. The cycles for the copy method will vary with >> allocation size, however, it is still faster even for the largest >> allocation that zsmalloc supports. >> >> The result is convenient though, as mempcy is very portable :) > > Today, I tested zsmapbench in my embedded board(ARM). > tlb-flush is 30% faster than copy-based so it's always not win. > I think it depends on CPU speed/cache size. > > zram is already very popular on embedded systems so I want to use > it continuously without 30% big demage so I want to keep our old approach > which supporting local tlb flush. > > Of course, in case of KVM guest, copy-based would be always bin win. > So shouldn't we support both approach? It could make code very ugly > but I think it has enough value. > > Any thought? Thanks for testing on ARM. I can add the pgtable assisted method back in, no problem. The question is by which criteria are we going to choose which method to use? By arch (i.e. ARM -> pgtable assist, x86 -> copy, other archs -> ?)? Also, what changes did you make to zsmapbench to measure elapsed time/cycles on ARM? Afaik, rdtscll() is not supported on ARM. Thanks, 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