From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1579BC4338F for ; Thu, 12 Aug 2021 21:19:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E835B60FED for ; Thu, 12 Aug 2021 21:19:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236698AbhHLVT0 (ORCPT ); Thu, 12 Aug 2021 17:19:26 -0400 Received: from cloud.peff.net ([104.130.231.41]:46058 "EHLO cloud.peff.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236417AbhHLVTU (ORCPT ); Thu, 12 Aug 2021 17:19:20 -0400 Received: (qmail 25127 invoked by uid 109); 12 Aug 2021 21:18:53 -0000 Received: from Unknown (HELO peff.net) (10.0.1.2) by cloud.peff.net (qpsmtpd/0.94) with ESMTP; Thu, 12 Aug 2021 21:18:53 +0000 Authentication-Results: cloud.peff.net; auth=none Received: (qmail 25605 invoked by uid 111); 12 Aug 2021 21:18:54 -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; Thu, 12 Aug 2021 17:18:54 -0400 Authentication-Results: peff.net; auth=none Date: Thu, 12 Aug 2021 17:18:52 -0400 From: Jeff King To: Taylor Blau Cc: git@vger.kernel.org, dstolee@microsoft.com, gitster@pobox.com, jonathantanmy@google.com Subject: Re: [PATCH v3 25/25] p5326: perf tests for MIDX bitmaps Message-ID: References: <82e8133bf4f6ecf2ca509f6d9e2e0d369d7f19e3.1627420428.git.me@ttaylorr.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <82e8133bf4f6ecf2ca509f6d9e2e0d369d7f19e3.1627420428.git.me@ttaylorr.com> Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Tue, Jul 27, 2021 at 05:20:28PM -0400, Taylor Blau wrote: > These new performance tests demonstrate effectively the same behavior as > p5310, but use a multi-pack bitmap instead of a single-pack one. > > Notably, p5326 does not create a MIDX bitmap with multiple packs. This > is so we can measure a direct comparison between it and p5310. Any > difference between the two is measuring just the overhead of using MIDX > bitmaps. > > Here are the results of p5310 and p5326 together, measured at the same > time and on the same machine (using a Xenon W-2255 CPU): Neat. I think having separate perf regression tests for regular and mix bitmaps will be useful, but being able to compare the pack and mix versions is a cherry on top. There was one funny number: > 5310.2: repack to disk 96.78(93.39+11.33) > 5326.2: setup multi-pack index 78.99(75.29+11.58) In p5310, that step is repacking and writing bitmaps. With the midx, it's repacking, then writing a midx with bitmaps. I'd expect the latter to be strictly slower than the former, but here it's faster. Running the code locally, I got similar results (with p5310 just a tiny bit faster). So it may have just been noise or some other timing issue. As an aside, I think that test is a little bit bogus due to GIT_PERF_REPEAT_COUNT; the first trial will generate bitmaps from scratch, and then subsequent runs will reuse partial results. It probably should "rm -f .git/objects/*.bitmap" within the test. We can deal with that separately, though. -Peff