Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754188Ab3GJJ4L (ORCPT ); Wed, 10 Jul 2013 05:56:11 -0400 Received: from LGEMRELSE7Q.lge.com ([156.147.1.151]:61973 "EHLO LGEMRELSE7Q.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753999Ab3GJJ4J (ORCPT ); Wed, 10 Jul 2013 05:56:09 -0400 X-AuditID: 9c930197-b7bfbae000000e88-30-51dd2fb7f36a Date: Wed, 10 Jul 2013 18:56:06 +0900 From: Joonsoo Kim To: Zhang Yanfei Cc: Michal Hocko , Zhang Yanfei , Andrew Morton , Mel Gorman , David Rientjes , Glauber Costa , Johannes Weiner , KOSAKI Motohiro , Rik van Riel , Hugh Dickins , Minchan Kim , Jiang Liu , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH 0/5] Support multiple pages allocation Message-ID: <20130710095606.GB5557@lge.com> References: <1372840460-5571-1-git-send-email-iamjoonsoo.kim@lge.com> <20130703152824.GB30267@dhcp22.suse.cz> <51D44890.4080003@gmail.com> <51D44AE7.1090701@gmail.com> <20130704042450.GA7132@lge.com> <20130704100044.GB7833@dhcp22.suse.cz> <20130710003142.GA2152@lge.com> <51DCB6DB.3070209@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <51DCB6DB.3070209@cn.fujitsu.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3081 Lines: 86 On Wed, Jul 10, 2013 at 09:20:27AM +0800, Zhang Yanfei wrote: > 于 2013/7/10 8:31, Joonsoo Kim 写道: > > On Thu, Jul 04, 2013 at 12:00:44PM +0200, Michal Hocko wrote: > >> On Thu 04-07-13 13:24:50, Joonsoo Kim wrote: > >>> On Thu, Jul 04, 2013 at 12:01:43AM +0800, Zhang Yanfei wrote: > >>>> On 07/03/2013 11:51 PM, Zhang Yanfei wrote: > >>>>> On 07/03/2013 11:28 PM, Michal Hocko wrote: > >>>>>> On Wed 03-07-13 17:34:15, Joonsoo Kim wrote: > >>>>>> [...] > >>>>>>> For one page allocation at once, this patchset makes allocator slower than > >>>>>>> before (-5%). > >>>>>> > >>>>>> Slowing down the most used path is a no-go. Where does this slow down > >>>>>> come from? > >>>>> > >>>>> I guess, it might be: for one page allocation at once, comparing to the original > >>>>> code, this patch adds two parameters nr_pages and pages and will do extra checks > >>>>> for the parameter nr_pages in the allocation path. > >>>>> > >>>> > >>>> If so, adding a separate path for the multiple allocations seems better. > >>> > >>> Hello, all. > >>> > >>> I modify the code for optimizing one page allocation via likely macro. > >>> I attach a new one at the end of this mail. > >>> > >>> In this case, performance degradation for one page allocation at once is -2.5%. > >>> I guess, remained overhead comes from two added parameters. > >>> Is it unreasonable cost to support this new feature? > >> > >> Which benchmark you are using for this testing? > > > > I use my own module which do allocation repeatedly. > > > >> > >>> I think that readahead path is one of the most used path, so this penalty looks > >>> endurable. And after supporting this feature, we can find more use cases. > >> > >> What about page faults? I would oppose that page faults are _much_ more > >> frequent than read ahead so you really cannot slow them down. > > > > You mean page faults for anon? > > Yes. I also think that it is much more frequent than read ahead. > > Before futher discussion, I will try to add a separate path > > for the multiple allocations. > > Some days ago, I was thinking that this multiple allocation behaviour > may be useful for vmalloc allocations. So I think it is worth trying. Yeh! I think so! Thanks. > > > > > Thanks. > > > >> > >> [...] > >> -- > >> Michal Hocko > >> SUSE Labs > >> > >> -- > >> 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 > > > > > -- > Thanks. > Zhang Yanfei > > -- > 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/