From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754926AbaBRL6y (ORCPT ); Tue, 18 Feb 2014 06:58:54 -0500 Received: from e23smtp01.au.ibm.com ([202.81.31.143]:42996 "EHLO e23smtp01.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752047AbaBRL6x (ORCPT ); Tue, 18 Feb 2014 06:58:53 -0500 Message-ID: <53034C66.90707@linux.vnet.ibm.com> Date: Tue, 18 Feb 2014 17:34:54 +0530 From: Raghavendra K T Organization: IBM User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130625 Thunderbird/17.0.7 MIME-Version: 1.0 To: Jan Kara CC: Andrew Morton , Fengguang Wu , David Cohen , Al Viro , Damien Ramonda , rientjes@google.com, Linus , nacc@linux.vnet.ibm.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH V6 ] mm readahead: Fix readahead fail for memoryless cpu and limit readahead pages References: <1392708338-19685-1-git-send-email-raghavendra.kt@linux.vnet.ibm.com> <20140218094920.GB29660@quack.suse.cz> In-Reply-To: <20140218094920.GB29660@quack.suse.cz> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14021811-1618-0000-0000-00000579093B Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/18/2014 03:19 PM, Jan Kara wrote: > On Tue 18-02-14 12:55:38, Raghavendra K T wrote: >> Currently max_sane_readahead() returns zero on the cpu having no local memory node >> which leads to readahead failure. Fix the readahead failure by returning >> minimum of (requested pages, 512). Users running application on a memory-less cpu >> which needs readahead such as streaming application see considerable boost in the >> performance. >> >> Result: >> fadvise experiment with FADV_WILLNEED on a PPC machine having memoryless CPU >> with 1GB testfile ( 12 iterations) yielded around 46.66% improvement. >> >> fadvise experiment with FADV_WILLNEED on a x240 machine with 1GB testfile >> 32GB* 4G RAM numa machine ( 12 iterations) showed no impact on the normal >> NUMA cases w/ patch. > Can you try one more thing please? Compare startup time of some big > executable (Firefox or LibreOffice come to my mind) for the patched and > normal kernel on a machine which wasn't hit by this NUMA issue. And don't > forget to do "echo 3 >/proc/sys/vm/drop_caches" before each test to flush > the caches. If this doesn't show significant differences, I'm OK with the > patch. > Thanks Honza, I checked with firefox (starting to particular point).. I do not see any difference. Both the case took around 14sec. ( some time it is even faster.. may be because we do not do free page calculation?. )