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: AS53758 23.128.96.0/24 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, SPF_HELO_PASS,SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by dcvr.yhbt.net (Postfix) with ESMTP id 900081F8C6 for ; Tue, 22 Jun 2021 19:42:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232649AbhFVToO (ORCPT ); Tue, 22 Jun 2021 15:44:14 -0400 Received: from cloud.peff.net ([104.130.231.41]:36350 "EHLO cloud.peff.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229786AbhFVToM (ORCPT ); Tue, 22 Jun 2021 15:44:12 -0400 Received: (qmail 6821 invoked by uid 109); 22 Jun 2021 19:39:56 -0000 Received: from Unknown (HELO peff.net) (10.0.1.2) by cloud.peff.net (qpsmtpd/0.94) with ESMTP; Tue, 22 Jun 2021 19:39:56 +0000 Authentication-Results: cloud.peff.net; auth=none Received: (qmail 29794 invoked by uid 111); 22 Jun 2021 19:39:56 -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, 22 Jun 2021 15:39:56 -0400 Authentication-Results: peff.net; auth=none Date: Tue, 22 Jun 2021 15:39:55 -0400 From: Jeff King To: Patrick Steinhardt Cc: Derrick Stolee , git@vger.kernel.org Subject: Re: [PATCH] bitmaps: don't recurse into trees already in the bitmap Message-ID: References: <471cb9be-bb72-6a37-ede8-f9421d9d3ebe@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Tue, Jun 22, 2021 at 12:47:57PM +0200, Patrick Steinhardt wrote: > Today I've been experimenting with the connectivity check of > git-receive-pack(1) once again to see whether I'm able to get a > performance improvement if the git-rev-list(1) command spawned as part > of the connectivity check uses `--use-bitmap-index`. > > Turns out the answer is "no": it has exactly the same performance > characteristics when pushing into a bitmapped repository (linux.git) > compared to the version not using a bitmap index, except for once case > where it performs 70x worse: force-pushing "master~10:master" into a > bitmapped repo takes 11s instead of 0.15s with bitmaps enabled. > > Just leaving this here as a note for anybody (or myself) to pick up at a > later point. Thanks. I'd wager that's probably the "we find the exact bitmap for the 'haves'" problem. There are probably a lot of old refs with so-so bitmap coverage, and we traverse all of them down to the nearest bitmap. If we filled in the bitmap by traversing commits in timestamp or generation order and ending at the merge-base, we could probably avoid looking at them at all. -Peff