From mboxrd@z Thu Jan 1 00:00:00 1970 From: Linus Torvalds Subject: Re: Performance issue of 'git branch' Date: Thu, 23 Jul 2009 09:25:06 -0700 (PDT) Message-ID: References: <20090722235914.GA13150@Pilar.aei.mpg.de> <20090723020238.GA8948@Pilar.aei.mpg.de> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: "Carlos R. Mafra" , git@vger.kernel.org To: Jakub Narebski X-From: git-owner@vger.kernel.org Thu Jul 23 18:25:40 2009 Return-path: Envelope-to: gcvg-git-2@gmane.org Received: from vger.kernel.org ([209.132.176.167]) by lo.gmane.org with esmtp (Exim 4.50) id 1MU16u-0003q1-GO for gcvg-git-2@gmane.org; Thu, 23 Jul 2009 18:25:37 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754525AbZGWQZd (ORCPT ); Thu, 23 Jul 2009 12:25:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754519AbZGWQZc (ORCPT ); Thu, 23 Jul 2009 12:25:32 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:45087 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754522AbZGWQZb (ORCPT ); Thu, 23 Jul 2009 12:25:31 -0400 Received: from imap1.linux-foundation.org (imap1.linux-foundation.org [140.211.169.55]) by smtp1.linux-foundation.org (8.14.2/8.13.5/Debian-3ubuntu1.1) with ESMTP id n6NGP6HH008633 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Thu, 23 Jul 2009 09:25:07 -0700 Received: from localhost (localhost [127.0.0.1]) by imap1.linux-foundation.org (8.13.5.20060308/8.13.5/Debian-3ubuntu1.1) with ESMTP id n6NGP6iQ003712; Thu, 23 Jul 2009 09:25:06 -0700 X-X-Sender: torvalds@localhost.localdomain In-Reply-To: User-Agent: Alpine 2.01 (LFD 1184 2008-12-16) X-Spam-Status: No, hits=-3.46 required=5 tests=AWL,BAYES_00 X-Spam-Checker-Version: SpamAssassin 3.2.4-osdl_revision__1.47__ X-MIMEDefang-Filter: lf$Revision: 1.188 $ X-Scanned-By: MIMEDefang 2.63 on 140.211.169.13 Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: On Thu, 23 Jul 2009, Jakub Narebski wrote: > > BTW. Would SystemTap help there? Among contributed scripts there is > iotimes, so perhaps it would be possible to have iotrace... The problem I've had with all iotracers is that it's easy enough to get an IO trace, but it's basically almost impossible to integrate it with what actually _caused_ the IO. Using 'strace -T' shows very clearly what operations are taking a long time. It's very useful for seeing what you should not do for good performance - including IO - and where it comes from. It's just that page faults are invisible to it. Linus