From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff King Subject: Re: [PATCH 0/2] optimizing pack access on "read only" fetch repos Date: Fri, 1 Feb 2013 04:14:31 -0500 Message-ID: <20130201091431.GC30644@sigill.intra.peff.net> References: <20130126224011.GA20675@sigill.intra.peff.net> <7vlibfxhit.fsf@alter.siamese.dyndns.org> <20130129082939.GB6396@sigill.intra.peff.net> <7vwquwrng6.fsf@alter.siamese.dyndns.org> <20130129211932.GA17377@sigill.intra.peff.net> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Cc: Junio C Hamano , git To: Shawn Pearce X-From: git-owner@vger.kernel.org Fri Feb 01 10:15:03 2013 Return-path: Envelope-to: gcvg-git-2@plane.gmane.org Received: from vger.kernel.org ([209.132.180.67]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1U1Ci2-0005Tz-Pg for gcvg-git-2@plane.gmane.org; Fri, 01 Feb 2013 10:14:59 +0100 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755971Ab3BAJOg (ORCPT ); Fri, 1 Feb 2013 04:14:36 -0500 Received: from 75-15-5-89.uvs.iplsin.sbcglobal.net ([75.15.5.89]:55319 "EHLO peff.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755837Ab3BAJOf (ORCPT ); Fri, 1 Feb 2013 04:14:35 -0500 Received: (qmail 19618 invoked by uid 107); 1 Feb 2013 09:15:58 -0000 Received: from c-71-206-173-132.hsd1.va.comcast.net (HELO sigill.intra.peff.net) (71.206.173.132) (smtp-auth username relayok, mechanism cram-md5) by peff.net (qpsmtpd/0.84) with ESMTPA; Fri, 01 Feb 2013 04:15:58 -0500 Received: by sigill.intra.peff.net (sSMTP sendmail emulation); Fri, 01 Feb 2013 04:14:31 -0500 Content-Disposition: inline In-Reply-To: Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: On Thu, Jan 31, 2013 at 08:47:37AM -0800, Shawn O. Pearce wrote: > >> - System resource cost we incur by having to keep 50 file > >> descriptors open and maintaining 50 mmap windows will reduce by > >> 50 fold. > > > > I wonder how measurable that is (and if it matters on Linux versus less > > efficient platforms). > > It does matter. We know it has a negative impact on JGit even on Linux > for example. You don't want 300 packs in a repository. 50 might be > tolerable. 300 is not. I'd love to see numbers if you have them. It's not that I don't believe it is slower, but knowing _how much_ is important when thinking about what kind of performance increase we are looking to get (which in turn impacts how much effort to put into the repacking). -Peff