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=-3.6 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 2A1E21FC43 for ; Fri, 6 Oct 2017 14:11:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752002AbdJFOLb (ORCPT ); Fri, 6 Oct 2017 10:11:31 -0400 Received: from cloud.peff.net ([104.130.231.41]:35272 "HELO cloud.peff.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751942AbdJFOLa (ORCPT ); Fri, 6 Oct 2017 10:11:30 -0400 Received: (qmail 5910 invoked by uid 109); 6 Oct 2017 14:11:30 -0000 Received: from Unknown (HELO peff.net) (10.0.1.2) by cloud.peff.net (qpsmtpd/0.94) with SMTP; Fri, 06 Oct 2017 14:11:30 +0000 Authentication-Results: cloud.peff.net; auth=none Received: (qmail 6500 invoked by uid 111); 6 Oct 2017 14:11:30 -0000 Received: from sigill.intra.peff.net (HELO sigill.intra.peff.net) (10.0.0.7) by peff.net (qpsmtpd/0.94) with SMTP; Fri, 06 Oct 2017 10:11:30 -0400 Authentication-Results: peff.net; auth=none Received: by sigill.intra.peff.net (sSMTP sendmail emulation); Fri, 06 Oct 2017 10:11:28 -0400 Date: Fri, 6 Oct 2017 10:11:28 -0400 From: Jeff King To: Derrick Stolee Cc: Junio C Hamano , Derrick Stolee , git@vger.kernel.org, git@jeffhostetler.com Subject: Re: [PATCH v2 1/5] test-list-objects: List a subset of object ids Message-ID: <20171006141128.rkuhd4m7hp2f7vvx@sigill.intra.peff.net> References: <20170925095452.66833-1-dstolee@microsoft.com> <20170925095452.66833-2-dstolee@microsoft.com> <20171005084249.sdkimglkxqh2vi4i@sigill.intra.peff.net> <20171005100001.do5m4zhexcsltvw7@sigill.intra.peff.net> <6222f65a-c518-74a4-9df4-89bf997425cb@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <6222f65a-c518-74a4-9df4-89bf997425cb@gmail.com> Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Thu, Oct 05, 2017 at 08:39:42AM -0400, Derrick Stolee wrote: > > Actually, I'd just as soon see timings for "git log --format=%h" or "git > > log --raw", as opposed to patches 1 and 2. > > > > You won't see a 90% speedup there, but you will see the actual > > improvement that real-world users are going to experience, which is way > > more important, IMHO. > > > Thanks for thinking hard about this. > > For some real-user context: Some engineers using Git for the Windows repo > were seeing extremely slow commands, such as 'fetch' or 'commit', and when > we took a trace we saw most of the time spinning in this abbreviation code. That's surprising to me. I'd expect fetch to generate up to two abbreviations per fetched ref (for the status table). And for commit to generate only one for the summary. But maybe it was just so painfully slow on your repo that it was noticeable. If there's a case where we're generating a bunch of abbreviated oids, that might be worth looking into. Do you happen to have a stack trace of one of the slow cases showing who is calling into the function? > Our workaround so far has been to set core.abbrev=40. I actually wondered about this. With the new auto-scaling, we'd typically jump straight to 12 or 13 hex-chars on a large repo, and that would be sufficient. So we'd really only need one iteration of the loop. > I'll run some perf numbers for these commands you recommend, and also see if > I can replicate some of the pain points that triggered this change using the > Linux repo. Thanks! -Peff