From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nguyen Thai Ngoc Duy Subject: Re: [RFC] pack-objects: compression level for non-blobs Date: Sat, 29 Dec 2012 12:25:04 +0700 Message-ID: References: <1353911154-23495-1-git-send-email-b@rr-dav.id.au> <20121229004104.GA24828@sigill.intra.peff.net> <20121229050707.GA14475@sigill.intra.peff.net> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: David Michael Barr , Git Mailing List To: Jeff King X-From: git-owner@vger.kernel.org Sat Dec 29 06:25:58 2012 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 1Toovi-0000OL-9Z for gcvg-git-2@plane.gmane.org; Sat, 29 Dec 2012 06:25:54 +0100 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751421Ab2L2FZg (ORCPT ); Sat, 29 Dec 2012 00:25:36 -0500 Received: from mail-ob0-f181.google.com ([209.85.214.181]:43547 "EHLO mail-ob0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751047Ab2L2FZf (ORCPT ); Sat, 29 Dec 2012 00:25:35 -0500 Received: by mail-ob0-f181.google.com with SMTP id oi10so10018450obb.40 for ; Fri, 28 Dec 2012 21:25:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-type; bh=8iHYzp50aS4j+uFAgTYB3bylxXLbuywS60oZYpQ0+hU=; b=guL/l7X49MNXgebLSUp/6QJi/5MVs35wi9tdESelEAQzgaqLQh3YiiqYDnzjg7jGIV R5pLlws2/X/iT9zmtpboZrbMz7LUO/5J3SfxpHE4915Qv8VdKyin0O5WEuitx/mZNBoV gLz5kX4qNgjtLlLnfHU9sv/5Ts4FteZxVegHTD0DxlAuZuKF4CrYfTQ+gkSpNl6f/R3r Nm8O9h5mh9BMOjP4qohrYa4qyKPnfQaTPa5Cc2dJsY3g9AWboEWk4B5+Q/IbVprAEj16 PvaQ8LreP40dyH4RHPkJeXB1zfSw/SjxFmsVuUXojQ3Tbg75vYJwFi35aeNTiao4xTUr IUcQ== Received: by 10.60.30.70 with SMTP id q6mr17262730oeh.107.1356758734699; Fri, 28 Dec 2012 21:25:34 -0800 (PST) Received: by 10.182.27.168 with HTTP; Fri, 28 Dec 2012 21:25:04 -0800 (PST) In-Reply-To: <20121229050707.GA14475@sigill.intra.peff.net> Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: On Sat, Dec 29, 2012 at 12:07 PM, Jeff King wrote: > On Sat, Dec 29, 2012 at 11:34:09AM +0700, Nguyen Thai Ngoc Duy wrote: > >> On Sat, Dec 29, 2012 at 7:41 AM, Jeff King wrote: >> > I wonder if we could do even better, though. For a traversal, we only >> > need to look at the commit header. We could potentially do a progressive >> > inflate and stop before getting to the commit message (which is the bulk >> > of the data, and the part that is most likely to benefit from >> > compression). >> >> Commit cache should solve this efficiently as it also eliminates >> parsing cost. We discussed this last time as a side topic of the >> reachability bitmap feature. > > I agree that a commit cache would solve this (though it can not help the > tree traversal). Yeah, caching trees efficiently is not easy. > But just dropping the compression (or doing partial > decompression when we only care about the beginning part) is way less > code and complexity. I think I tried the partial decompression for commit header and it did not help much (or I misremember it, not so sure). > There's no cache to manage. If reachability bitmap is implemented, we'll have per-pack cache infrastructure ready, so less work there for commit cache. -- Duy