From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id E6E6460021B for ; Mon, 28 Dec 2009 23:05:38 -0500 (EST) Received: by pxi2 with SMTP id 2so7540260pxi.11 for ; Mon, 28 Dec 2009 20:05:37 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20091228164451.A687.A69D9226@jp.fujitsu.com> References: <20091228164451.A687.A69D9226@jp.fujitsu.com> Date: Tue, 29 Dec 2009 13:05:37 +0900 Message-ID: <28c262360912282005x68315a62l7ffde637febc7646@mail.gmail.com> Subject: Re: [PATCH 1/4] vmstat: remove zone->lock from walk_zones_in_node From: Minchan Kim Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org To: KOSAKI Motohiro Cc: LKML , linux-mm , Andrew Morton , Balbir Singh , Mel Gorman , KAMEZAWA Hiroyuki List-ID: On Mon, Dec 28, 2009 at 4:47 PM, KOSAKI Motohiro wrote: > The zone->lock is one of performance critical locks. Then, it shouldn't > be hold for long time. Currently, we have four walk_zones_in_node() > usage and almost use-case don't need to hold zone->lock. I agree. We can use walk_zone_in_node freely to show the information related to zone. - frag_show_print : the number of free pages per order. - pagetypeinfo_showfree_print : the number of free page per migration type - pagetypeinfo_showblockcount_print : the number of pages in zone per migration type - zoneinfo_show_print : many info about zone. Do we want to show exact value? No. If we want it, it's not enough zone->lock only. After all, All of things would be transient value. > > Thus, this patch move locking responsibility from walk_zones_in_node > to its sub function. Also this patch kill unnecessary zone->lock taking. > > Cc: Mel Gorman > Signed-off-by: KOSAKI Motohiro Reviewed-by: Minchan Kim -- Kind regards, Minchan Kim -- 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