From mboxrd@z Thu Jan  1 00:00:00 1970
From: Nicolas Pitre <nico@cam.org>
Subject: Re: Performance problem, long run of identical hashes
Date: Mon, 10 Dec 2007 10:45:49 -0500 (EST)
Message-ID: <alpine.LFD.0.99999.0712101037270.555@xanadu.home>
References: <9e4733910712100707i66e185bofe22805b8e0ba4d8@mail.gmail.com>
Mime-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Content-Transfer-Encoding: 7BIT
Cc: Git Mailing List <git@vger.kernel.org>
To: Jon Smirl <jonsmirl@gmail.com>
X-From: git-owner@vger.kernel.org Mon Dec 10 16:46:39 2007
Return-path: <git-owner@vger.kernel.org>
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 1J1kpj-0002ed-1K
	for gcvg-git-2@gmane.org; Mon, 10 Dec 2007 16:46:15 +0100
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1752858AbXLJPpy (ORCPT <rfc822;gcvg-git-2@m.gmane.org>);
	Mon, 10 Dec 2007 10:45:54 -0500
Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752374AbXLJPpy
	(ORCPT <rfc822;git-outgoing>); Mon, 10 Dec 2007 10:45:54 -0500
Received: from relais.videotron.ca ([24.201.245.36]:64486 "EHLO
	relais.videotron.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1751899AbXLJPpw (ORCPT <rfc822;git@vger.kernel.org>);
	Mon, 10 Dec 2007 10:45:52 -0500
Received: from xanadu.home ([74.56.106.175]) by VL-MO-MR005.ip.videotron.ca
 (Sun Java(tm) System Messaging Server 6.3-4.01 (built Aug  3 2007; 32bit))
 with ESMTP id <0JSU0016NBSC9920@VL-MO-MR005.ip.videotron.ca> for
 git@vger.kernel.org; Mon, 10 Dec 2007 10:45:48 -0500 (EST)
X-X-Sender: nico@xanadu.home
In-reply-to: <9e4733910712100707i66e185bofe22805b8e0ba4d8@mail.gmail.com>
User-Agent: Alpine 0.99999 (LFD 814 2007-11-14)
Sender: git-owner@vger.kernel.org
Precedence: bulk
List-ID: <git.vger.kernel.org>
X-Mailing-List: git@vger.kernel.org
Archived-At: <http://permalink.gmane.org/gmane.comp.version-control.git/67724>

On Mon, 10 Dec 2007, Jon Smirl wrote:

> Running oprofile during my gcc repack shows this loop as the hottest
> place in the code by far.

Well, that is kind of expected.

> I added some debug printfs which show that I
> have a 100,000+ run of identical hash entries. Processing the 100,000
> entries also causes RAM consumption to explode.

That is impossible.  If you look at the code where those hash entries 
are created in create_delta_index(), you'll notice a hard limit of 
HASH_LIMIT (currently 64) is imposed on the number of identical hash 
entries.


Nicolas