From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-3.9 required=3.0 tests=AWL,BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI, RCVD_IN_MSPIKE_H3,RCVD_IN_MSPIKE_WL,SPF_HELO_NONE,SPF_NONE shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id C99871F45D for ; Tue, 24 Mar 2020 06:06:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726034AbgCXGGj (ORCPT ); Tue, 24 Mar 2020 02:06:39 -0400 Received: from cloud.peff.net ([104.130.231.41]:49062 "HELO cloud.peff.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1725869AbgCXGGi (ORCPT ); Tue, 24 Mar 2020 02:06:38 -0400 Received: (qmail 15144 invoked by uid 109); 24 Mar 2020 06:06:39 -0000 Received: from Unknown (HELO peff.net) (10.0.1.2) by cloud.peff.net (qpsmtpd/0.94) with SMTP; Tue, 24 Mar 2020 06:06:39 +0000 Authentication-Results: cloud.peff.net; auth=none Received: (qmail 21196 invoked by uid 111); 24 Mar 2020 06:16:27 -0000 Received: from coredump.intra.peff.net (HELO sigill.intra.peff.net) (10.0.0.2) by peff.net (qpsmtpd/0.94) with (TLS_AES_256_GCM_SHA384 encrypted) ESMTPS; Tue, 24 Mar 2020 02:16:27 -0400 Authentication-Results: peff.net; auth=none Date: Tue, 24 Mar 2020 02:06:37 -0400 From: Jeff King To: Taylor Blau Cc: git@vger.kernel.org, dstolee@microsoft.com Subject: Re: [PATCH 1/1] commit-graph.c: avoid unnecessary tag dereference when merging Message-ID: <20200324060637.GB610977@coredump.intra.peff.net> References: <4c79a9ea909ebff8c0987bcf95692da92e79bda4.1584762087.git.me@ttaylorr.com> <20200321050025.GA1438317@coredump.intra.peff.net> <20200321061141.GA30636@syl.local> <20200321070333.GB1441446@coredump.intra.peff.net> <20200321172716.GA39461@syl.local> <20200322053635.GA578498@coredump.intra.peff.net> <20200322164531.GA55067@syl.local> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200322164531.GA55067@syl.local> Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Sun, Mar 22, 2020 at 10:45:31AM -0600, Taylor Blau wrote: > So, I'm not sure what was going on with my original measurements, other > than that I took them around midnight, so the chance for error was > probably high. I'll go with your measurements, since they are both > closer to what we'd see in the real world, and actually representative > of the change here. I wondered if perhaps you had stray commit-graph files sitting around. I don't think we'd look at them if they aren't mentioned in the commit-graphs index, though. And anyway, feeding all of the packed objects would mean those would all be parsed in the earlier stage, so even if we _did_ have a bunch of stuff to merge, it would have been fast even with the old code. So...I dunno. One other thing that's bitten me in the past is accidentally compiling with the wrong optimization settings. I have my config.mak set up to compile with -O0 by default (because it's faster and because I'm frequently debugging anyway), and then I do a -O2 build for my daily driver. But when performance testing, I sometimes accidentally compare -O0 and -O2 builds to each other. That's all very specific to my config.mak setup, but I know you've picked up some of it, so it's possible you inherited that subtlety. :) -Peff