From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx192.postini.com [74.125.245.192]) by kanga.kvack.org (Postfix) with SMTP id E01326B004F for ; Fri, 6 Jan 2012 01:14:01 -0500 (EST) Message-ID: <4F069120.8060300@tao.ma> Date: Fri, 06 Jan 2012 14:13:52 +0800 From: Tao Ma MIME-Version: 1.0 Subject: Re: [PATCH] mm: do not drain pagevecs for mlock References: <1325226961-4271-1-git-send-email-tm@tao.ma> <4EFD7AE3.8020403@tao.ma> <4EFD8832.6010905@tao.ma> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: KOSAKI Motohiro Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, David Rientjes , Minchan Kim , Mel Gorman , Johannes Weiner , Andrew Morton Hi Kosaki, On 12/30/2011 06:07 PM, KOSAKI Motohiro wrote: >>> Because your test program is too artificial. 20sec/100000times = >>> 200usec. And your >>> program repeat mlock and munlock the exact same address. so, yes, if >>> lru_add_drain_all() is removed, it become near no-op. but it's >>> worthless comparision. >>> none of any practical program does such strange mlock usage. >> yes, I should say it is artificial. But mlock did cause the problem in >> our product system and perf shows that the mlock uses the system time >> much more than others. That's the reason we created this program to test >> whether mlock really sucks. And we compared the result with >> rhel5(2.6.18) which runs much much faster. >> >> And from the commit log you described, we can remove lru_add_drain_all >> safely here, so why add it? At least removing it makes mlock much faster >> compared to the vanilla kernel. > > If we remove it, we lose to a test way of mlock. "Memlocked" field of > /proc/meminfo > show inaccurate number very easily. So, if 200usec is no avoidable, > I'll ack you. > But I'm not convinced yet. Do you find something new for this? Thanks Tao -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org