From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m5.gw.fujitsu.co.jp ([10.0.50.75]) by fgwmail6.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id mARB8VS5004791 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Thu, 27 Nov 2008 20:08:31 +0900 Received: from smail (m5 [127.0.0.1]) by outgoing.m5.gw.fujitsu.co.jp (Postfix) with ESMTP id D778645DE55 for ; Thu, 27 Nov 2008 20:08:30 +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 B500345DE52 for ; Thu, 27 Nov 2008 20:08:30 +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 63FD11DB8045 for ; Thu, 27 Nov 2008 20:08:30 +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 1D5AD1DB8038 for ; Thu, 27 Nov 2008 20:08:30 +0900 (JST) From: KOSAKI Motohiro Subject: Re: [RFC v1][PATCH]page_fault retry with NOPAGE_RETRY In-Reply-To: <1227780007.4454.1344.camel@twins> References: <492E6849.6090205@google.com> <1227780007.4454.1344.camel@twins> Message-Id: <20081127200501.3CF9.KOSAKI.MOTOHIRO@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Date: Thu, 27 Nov 2008 20:08:29 +0900 (JST) Sender: owner-linux-mm@kvack.org Return-Path: To: Peter Zijlstra Cc: kosaki.motohiro@jp.fujitsu.com, Mike Waychison , Nick Piggin , Ying Han , Ingo Molnar , linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm , David Rientjes , Rohit Seth , Hugh Dickins , "H. Peter Anvin" , edwintorok@gmail.com List-ID: > Furthermore, /proc code usually isn't written with performance in mind, > so its usually simple and robust code. Adding it to a 'hot'-path like > you're doing doesn't seem advisable. > > Also, releasing and re-acquiring mmap_sem can significantly add to the > cacheline bouncing that thing already has. Interesting. I tryed to demonstration /proc slowness. 1. make many process $ nice ./hackbench 120 process 10000 2. read /proc $ time ps -ef 0.16s user 0.57s system 1% cpu 46.859 total HAHAHA! That is really slow over my expected. -- 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