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-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 E23341F9FC for ; Thu, 18 Mar 2021 22:55:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232657AbhCRWyu (ORCPT ); Thu, 18 Mar 2021 18:54:50 -0400 Received: from cloud.peff.net ([104.130.231.41]:41664 "EHLO cloud.peff.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232676AbhCRWyo (ORCPT ); Thu, 18 Mar 2021 18:54:44 -0400 Received: (qmail 1804 invoked by uid 109); 18 Mar 2021 22:54:43 -0000 Received: from Unknown (HELO peff.net) (10.0.1.2) by cloud.peff.net (qpsmtpd/0.94) with ESMTP; Thu, 18 Mar 2021 22:54:43 +0000 Authentication-Results: cloud.peff.net; auth=none Received: (qmail 25966 invoked by uid 111); 18 Mar 2021 22:54:44 -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, 18 Mar 2021 18:54:44 -0400 Authentication-Results: peff.net; auth=none Date: Thu, 18 Mar 2021 18:54:42 -0400 From: Jeff King To: Martin Fick Cc: Han-Wen Nienhuys , git Subject: Re: Distinguishing FF vs non-FF updates in the reflog? Message-ID: References: <5359503.g8GvsOHjsp@mfick-lnx> <21556546.pz8f0XPdgJ@mfick-lnx> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <21556546.pz8f0XPdgJ@mfick-lnx> Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Thu, Mar 18, 2021 at 04:31:24PM -0600, Martin Fick wrote: > On Thursday, March 18, 2021 9:58:56 AM MDT Han-Wen Nienhuys wrote: > > The bitmaps are generated by GC, and you can't GC all the time. > > I believe that I recently saw an effort to make this incremental, perhaps > related to the geometric repacking series? If that were the case, you could gc > much more often cheaply. Perhaps it could be something done on every upload at > some point the way that reflog effectively does on every update? That geometric repacking work is leading up to having a bitmap for a multi-pack-index. Which will make them _cheaper_, but still not especially cheap (because we've reordered the objects corresponding to each bit, and also because our writing process still does a lot of O(nr_commits) work). In the very long run, I think the way out would be to stop using pack or midx ordering as the basis of the bitmap, and instead have a stable object ordering that can be appended to. That would allow true incremental generation of the bitmaps (leaving old ones in place, and just adding a new ones to represent new commits). But that's such a big departure from the status quo that having a midx bitmap seemed like a more attainable middle ground in the meantime. -Peff