From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Shawn O. Pearce" Subject: Re: [PATCHv5 00/14] git notes Date: Sat, 12 Sep 2009 11:11:50 -0700 Message-ID: <20090912181150.GN1033@spearce.org> References: <1252376822-6138-1-git-send-email-johan@herland.net> <200909080512.34634.johan@herland.net> <200909121750.00733.johan@herland.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: git@vger.kernel.org, gitster@pobox.com, Johannes.Schindelin@gmx.de, trast@student.ethz.ch, tavestbo@trolltech.com, git@drmicha.warpmail.net, chriscool@tuxfamily.org To: Johan Herland X-From: git-owner@vger.kernel.org Sat Sep 12 20:11:59 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 1MmX4o-0004UW-7o for gcvg-git-2@lo.gmane.org; Sat, 12 Sep 2009 20:11:58 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754434AbZILSLt (ORCPT ); Sat, 12 Sep 2009 14:11:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753368AbZILSLs (ORCPT ); Sat, 12 Sep 2009 14:11:48 -0400 Received: from george.spearce.org ([209.20.77.23]:49731 "EHLO george.spearce.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752956AbZILSLr (ORCPT ); Sat, 12 Sep 2009 14:11:47 -0400 Received: by george.spearce.org (Postfix, from userid 1001) id CA227381FD; Sat, 12 Sep 2009 18:11:50 +0000 (UTC) Content-Disposition: inline In-Reply-To: <200909121750.00733.johan@herland.net> User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: Johan Herland wrote: > Shawn, do you have any additional defence for the date-based fanout? No. The only defense I have for it is "it sounds like a nice theory given access patterns", and the note about memory usage you made, but which I clipped to keep this email shorter. :-) It was only a theory I tossed out there in a back-seat-driver sort of way. Your results show my hunch was correct, it may help. But they also say it may not help enough to justify the complexity, so I now agree with you that SHA-1 fan out may be good enough. > Are > there untested reasonable scenarios that would show the benefits of date- > based fanout? I don't think there are, your tests were pretty good at covering things. > How does the plan for notes usage in your code-review thingy > compare to my test scenario? I think your tests may still have been too low in volume, 115k notes isn't a lot. Based on the distributions I was looking at before, I could be seeing a growth of >100k notes/year. Ask me again in 5 years if 115k notes is a lot. :-) But we all know that SHA-1 distributes data quite well, so the SHA-1 fan-out may just need to change from 2_38 to 2_2_2_34 (or something) to handle that larger volume. -- Shawn.