From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx101.postini.com [74.125.245.101]) by kanga.kvack.org (Postfix) with SMTP id 128016B004D for ; Fri, 30 Dec 2011 05:08:19 -0500 (EST) Received: by yhgm50 with SMTP id m50so7973357yhg.14 for ; Fri, 30 Dec 2011 02:08:18 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <4EFD8832.6010905@tao.ma> References: <1325226961-4271-1-git-send-email-tm@tao.ma> <4EFD7AE3.8020403@tao.ma> <4EFD8832.6010905@tao.ma> From: KOSAKI Motohiro Date: Fri, 30 Dec 2011 05:07:57 -0500 Message-ID: Subject: Re: [PATCH] mm: do not drain pagevecs for mlock Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Tao Ma Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, David Rientjes , Minchan Kim , Mel Gorman , Johannes Weiner , Andrew Morton >> 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. -- 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