From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f53.google.com (mail-pa0-f53.google.com [209.85.220.53]) by kanga.kvack.org (Postfix) with ESMTP id 2D3086B0031 for ; Tue, 18 Feb 2014 06:59:00 -0500 (EST) Received: by mail-pa0-f53.google.com with SMTP id lj1so16625175pab.12 for ; Tue, 18 Feb 2014 03:58:59 -0800 (PST) Received: from e23smtp02.au.ibm.com (e23smtp02.au.ibm.com. [202.81.31.144]) by mx.google.com with ESMTPS id zk9si18060917pac.347.2014.02.18.03.58.58 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Tue, 18 Feb 2014 03:58:59 -0800 (PST) Received: from /spool/local by e23smtp02.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 18 Feb 2014 21:58:53 +1000 Received: from d23relay03.au.ibm.com (d23relay03.au.ibm.com [9.190.235.21]) by d23dlp01.au.ibm.com (Postfix) with ESMTP id 158252CE8055 for ; Tue, 18 Feb 2014 22:58:50 +1100 (EST) Received: from d23av04.au.ibm.com (d23av04.au.ibm.com [9.190.235.139]) by d23relay03.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id s1IBwYgY10486260 for ; Tue, 18 Feb 2014 22:58:36 +1100 Received: from d23av04.au.ibm.com (localhost [127.0.0.1]) by d23av04.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id s1IBwlGx000933 for ; Tue, 18 Feb 2014 22:58:47 +1100 Message-ID: <53034C66.90707@linux.vnet.ibm.com> Date: Tue, 18 Feb 2014 17:34:54 +0530 From: Raghavendra K T MIME-Version: 1.0 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 Sender: owner-linux-mm@kvack.org List-ID: 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 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?. ) -- 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