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 357CD8D0039 for ; Wed, 2 Mar 2011 22:20:52 -0500 (EST) Message-ID: <4D6F077B.3060400@tao.ma> Date: Thu, 03 Mar 2011 11:14:03 +0800 From: Tao Ma MIME-Version: 1.0 Subject: Re: [RFC PATCH 4/5] mm: Add hit/miss accounting for Page Cache References: <1299055090-23976-4-git-send-email-namei.unix@gmail.com> <20110302084542.GA20795@elte.hu> In-Reply-To: <20110302084542.GA20795@elte.hu> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Ingo Molnar Cc: Liu Yuan , linux-kernel@vger.kernel.org, linux-mm@kvack.org, jaxboe@fusionio.com, akpm@linux-foundation.org, fengguang.wu@intel.com, Peter Zijlstra , =?ISO-8859-1?Q?Fr=E9d=E9ric_Weisbecker?= , Steven Rostedt , Thomas Gleixner , Arnaldo Carvalho de Melo On 03/02/2011 04:45 PM, Ingo Molnar wrote: > * Liu Yuan wrote: > > >> + if (likely(!retry_find)&& page&& PageUptodate(page)) >> + page_cache_acct_hit(inode->i_sb, READ); >> + else >> + page_cache_acct_missed(inode->i_sb, READ); >> > Sigh. > > This would make such a nice tracepoint or sw perf event. It could be collected in a > 'count' form, equivalent to the stats you are aiming for here, or it could even be > traced, if someone is interested in such details. > > It could be mixed with other events, enriching multiple apps at once. > > But, instead of trying to improve those aspects of our existing instrumentation > frameworks, mm/* is gradually growing its own special instrumentation hacks, missing > the big picture and fragmenting the instrumentation space some more. > Thanks for the quick response. Actually our team(including Liu) here are planing to add some debug info to the mm parts for analyzing the application behavior and hope to find some way to improve our application's performance. We have searched the trace points in mm, but it seems to us that the trace points isn't quite welcomed there. Only vmscan and writeback have some limited trace points added. That's the reason we first tried to add some debug info like this patch. You does shed some light on our direction. Thanks. btw, what part do you think is needed to add some trace point? We volunteer to add more if you like. Regards, 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