From mboxrd@z Thu Jan 1 00:00:00 1970 From: Linus Torvalds Subject: Re: obnoxious CLI complaints Date: Fri, 11 Sep 2009 07:47:01 -0700 (PDT) Message-ID: References: <200909101116.55098.jnareb@gmail.com> <4AA97B61.6030301@lsrfire.ath.cx> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=ISO-8859-2 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Jakub Narebski , Brendan Miller , git@vger.kernel.org To: =?ISO-8859-15?Q?Ren=E9_Scharfe?= X-From: git-owner@vger.kernel.org Fri Sep 11 16:48:08 2009 Return-path: Envelope-to: gcvg-git-2@lo.gmane.org Received: from vger.kernel.org ([209.132.176.167]) by lo.gmane.org with esmtp (Exim 4.50) id 1Mm7Pu-0004Us-QE for gcvg-git-2@lo.gmane.org; Fri, 11 Sep 2009 16:48:03 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752684AbZIKOrw convert rfc822-to-quoted-printable (ORCPT ); Fri, 11 Sep 2009 10:47:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752179AbZIKOrw (ORCPT ); Fri, 11 Sep 2009 10:47:52 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:38565 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752109AbZIKOrv (ORCPT ); Fri, 11 Sep 2009 10:47:51 -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 n8BEl1wW015104 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Fri, 11 Sep 2009 07:47:02 -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 n8BEl1bQ002977; Fri, 11 Sep 2009 07:47:01 -0700 X-X-Sender: torvalds@localhost.localdomain In-Reply-To: <4AA97B61.6030301@lsrfire.ath.cx> User-Agent: Alpine 2.01 (LFD 1184 2008-12-16) X-Spam-Status: No, hits=-3.458 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 Fri, 11 Sep 2009, Ren=E9 Scharfe wrote: >=20 > Using zlib directly avoids the overhead of a pipe and of buffering th= e > output for blocked writes; surprisingly (to me), it isn't any faster. In fact, it should be slower. On SMP, you're quite likely better off using the pipe, and compressing = on=20 another CPU. Of course, it's usually the case that the compression is _= so_=20 much slower than generating the tar-file (especially for the hot-cache=20 case) that it doesn't matter or the pipe overhead is even a slowdown. But especially if generating the tar-file has some delays in it=20 (cold-cache object lookup, whatever), the "compress in separate process= "=20 is likely simply better, because you can compress while the other proce= ss=20 is looking up data for the tar. Linus