From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with SMTP id 1C3AE6B00B0 for ; Tue, 17 Feb 2009 19:29:08 -0500 (EST) Received: from m5.gw.fujitsu.co.jp ([10.0.50.75]) by fgwmail6.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id n1I0T6LX024009 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Wed, 18 Feb 2009 09:29:06 +0900 Received: from smail (m5 [127.0.0.1]) by outgoing.m5.gw.fujitsu.co.jp (Postfix) with ESMTP id 20DCE45DE53 for ; Wed, 18 Feb 2009 09:29:06 +0900 (JST) Received: from s5.gw.fujitsu.co.jp (s5.gw.fujitsu.co.jp [10.0.50.95]) by m5.gw.fujitsu.co.jp (Postfix) with ESMTP id 001EF45DE52 for ; Wed, 18 Feb 2009 09:29:06 +0900 (JST) Received: from s5.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s5.gw.fujitsu.co.jp (Postfix) with ESMTP id DC78D1DB805E for ; Wed, 18 Feb 2009 09:29:05 +0900 (JST) Received: from ml14.s.css.fujitsu.com (ml14.s.css.fujitsu.com [10.249.87.104]) by s5.gw.fujitsu.co.jp (Postfix) with ESMTP id 899A01DB803C for ; Wed, 18 Feb 2009 09:29:05 +0900 (JST) From: KOSAKI Motohiro Subject: Re: [PATCH] Add tracepoints to track pagecache transition In-Reply-To: <20090217143321.GB5888@nowhere> References: <20090217201651.576E.A69D9226@jp.fujitsu.com> <20090217143321.GB5888@nowhere> Message-Id: <20090218091726.898D.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Date: Wed, 18 Feb 2009 09:29:04 +0900 (JST) Sender: owner-linux-mm@kvack.org To: Frederic Weisbecker Cc: kosaki.motohiro@jp.fujitsu.com, Atsushi Tsuji , Peter Zijlstra , linux-kernel@vger.kernel.org, Jason Baron , Ingo Molnar , Mathieu Desnoyers , "Frank Ch. Eigler" , Kazuto Miyoshi , rostedt@goodmis.org, linux-mm , Andrew Morton , Nick Piggin , Hugh Dickins List-ID: Hi Frederic, > > And, both function is freqentlly called one. > > I worry about performance issue. can you prove no degression? > > It would be very hard to prove. Tracepoints are very cheap in that they only > add the overhead of a single branch check while off. this is typical reviewing comment. Memory folks adage says, Don't believe theory, you believe benchmark result. I don't oppose your theorical background opinion :) > But are there some plans about writing a tracer or so for pagecache? -- 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