From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nicolas Pitre Subject: observations on parsecvs testing Date: Thu, 15 Jun 2006 16:37:30 -0400 (EDT) Message-ID: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Content-Transfer-Encoding: 7BIT Cc: git@vger.kernel.org X-From: git-owner@vger.kernel.org Thu Jun 15 22:37:43 2006 Return-path: Envelope-to: gcvg-git@gmane.org Received: from vger.kernel.org ([209.132.176.167]) by ciao.gmane.org with esmtp (Exim 4.43) id 1Fqyas-00045j-8g for gcvg-git@gmane.org; Thu, 15 Jun 2006 22:37:35 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751336AbWFOUhb (ORCPT ); Thu, 15 Jun 2006 16:37:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751420AbWFOUhb (ORCPT ); Thu, 15 Jun 2006 16:37:31 -0400 Received: from relais.videotron.ca ([24.201.245.36]:49080 "EHLO relais.videotron.ca") by vger.kernel.org with ESMTP id S1751336AbWFOUhb (ORCPT ); Thu, 15 Jun 2006 16:37:31 -0400 Received: from xanadu.home ([74.56.108.184]) by VL-MO-MR001.ip.videotron.ca (Sun Java System Messaging Server 6.2-2.05 (built Apr 28 2005)) with ESMTP id <0J0X00ARS5AIO600@VL-MO-MR001.ip.videotron.ca> for git@vger.kernel.org; Thu, 15 Jun 2006 16:37:30 -0400 (EDT) X-X-Sender: nico@localhost.localdomain To: Keith Packard Sender: git-owner@vger.kernel.org Precedence: bulk X-Mailing-List: git@vger.kernel.org Archived-At: My machine is a P4 @ 3GHz with 1GB ram. Feeding parsecvs with the Mozilla repository, it first ran for 175 minutes with about 98% CPU spent in user space reading the 100458 ,v files and writing 700000+ blob objects. Memory usage grew to 1789MB total while the resident memory saturated around 700MB. This part was fine even with 1GB of ram since unused memory was gently pushed to swap. Only problem is that spawned git-pack-object instances started failing with memory allocation by that time, which is unffortunate but not fatal. But then things started to go bad after all ,v files were parsed. The parsecvs dropped to 3% CPU while the rest of the time was spent waiting after swap IO and therefore no substantial progress was made at that point. So the Mozilla clearly requires 2GB of ram to realistically be converted to GIT using parsecvs, unless its second phase is reworked to avoid totally random access in memory in order to improve swap behavior, or its in-memory data set is shrinked at least by half. Also rcs2git() is very inefficient especially with files having many revisions as it reconstructs the delta chain on every call. For example mozilla/configure,v has at least 1690 revisions, and actually converting it into GIT blobs goes at a rate of 2.4 objects per second _only_ on my machine. Can't objects be created as the delta list is walked/applied instead? That would significantly reduce the initial convertion time. Nicolas