From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-4.8 required=3.0 tests=AWL,BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_HI,RP_MATCHES_RCVD shortcircuit=no autolearn=ham autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id C8D6D207DF for ; Thu, 15 Sep 2016 06:28:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933799AbcIOG2v (ORCPT ); Thu, 15 Sep 2016 02:28:51 -0400 Received: from cloud.peff.net ([104.130.231.41]:43550 "EHLO cloud.peff.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756182AbcIOG2v (ORCPT ); Thu, 15 Sep 2016 02:28:51 -0400 Received: (qmail 12945 invoked by uid 109); 15 Sep 2016 06:28:49 -0000 Received: from Unknown (HELO peff.net) (10.0.1.2) by cloud.peff.net (qpsmtpd/0.84) with SMTP; Thu, 15 Sep 2016 06:28:49 +0000 Received: (qmail 7006 invoked by uid 111); 15 Sep 2016 06:29:00 -0000 Received: from Unknown (HELO sigill.intra.peff.net) (10.0.1.3) by peff.net (qpsmtpd/0.84) with SMTP; Thu, 15 Sep 2016 02:29:00 -0400 Received: by sigill.intra.peff.net (sSMTP sendmail emulation); Wed, 14 Sep 2016 23:28:46 -0700 Date: Wed, 14 Sep 2016 23:28:46 -0700 From: Jeff King To: Stefan Beller Cc: "git@vger.kernel.org" Subject: Re: [PATCH 2/2] use zstd zlib wrapper Message-ID: <20160915062845.sfackmnezb7oy3j5@sigill.intra.peff.net> References: <20160914235547.h3n2otje2hec6u7k@sigill.intra.peff.net> <20160914235843.nacr54ekvl6rjipk@sigill.intra.peff.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Wed, Sep 14, 2016 at 06:22:17PM -0700, Stefan Beller wrote: > > Disappointingly, the answer seems to be "no". > > After having looked at the data, I disagree with the conclusion. > And for that I think we need to reason about the frequency > of the operations happening. I definitely agree that reads outnumber writes, and it's OK to have an asymmetric tradeoff between the two. zstd5 isn't _too_ bad in that respect. I guess I was just disappointed that the pack size was still bigger, as I was really hoping to see some speed tradeoff without getting a worse pack. The other thing to weigh against is "if we were designing it today" versus "is it worth the compatibility headaches now". A 6% improvement in "rev-list --objects" is not that amazing for a data format change. Bitmaps were an _easier_ data format change and are more like a 99% speedup. They do not apply to every operations, but we may be able to do similar space/time tradeoffs that are easier to handle in terms of backwards compatibility, and which yield bigger results. -Peff