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From: SZEDER Gábor <szeder.dev@gmail.com>
To: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Cc: Jeff King <peff@peff.net>, Derrick Stolee <dstolee@microsoft.com>,
	Junio C Hamano <gitster@pobox.com>, Eric Wong <e@80x24.org>,
	git@vger.kernel.org
Subject: Re: [PATCH v3] repack: enable bitmaps by default on bare repos
Date: Fri, 24 May 2019 13:41:14 +0200
Message-ID: <20190524114114.GH951@szeder.dev> (raw)
In-Reply-To: <87imu0f6fh.fsf@evledraar.gmail.com>

On Fri, May 24, 2019 at 01:17:06PM +0200, Ævar Arnfjörð Bjarmason wrote:
> 
> On Fri, May 24 2019, SZEDER Gábor wrote:
> 
> > On Fri, May 24, 2019 at 11:01:39AM +0200, Ævar Arnfjörð Bjarmason wrote:
> >> I don't think it's a performance problem to have an old commit-graph
> >> lying around. But if you turn on the commit-graph, run gc a bunch, then
> >> turn it off in config we'll have it lying around forever, even if you do
> >> subsequent gc's.
> >>
> >> So I think we should delete such things on the general principle that
> >> the end-state of a gc's shouldn't be the accumulation of the values of
> >> past configuration options if we can help it.
> >>
> >> Maybe that screws over other users who did a "commit-graph write"
> >> without setting gc.writeCommitGraph, but I think the only sane thing to
> >> do is to make "gc" fully 'own' such things if its turned on at all.
> >
> > Note that there is 'core.commitGraph' as well; as long as it's
> > enabled, no commit-graph files should be deleted.
> 
> Why? If we won't update it or write it if it's not there, why keep it
> around?

To read it, if 'core.commitGraph' says that is should be read.

> It means the commit-graph code and anything else (like bitmaps) needs to
> deal with stale data for the common and default gc --auto case.
> 
> You also can't have e.g. a global core.commitGraph=true config along
> with a per-repo gc.writeCommitGraph=true config do what you expect.
> 
> Now just because you wanted to write it for some you'll end up keeping
> it around forever because you'd also want to optimistically always use
> it if it's there.

This is exactly what I expect it to do.


> Note that I'm talking about the *default* gc semantics, they don't have
> to cover all advanced use-cases, just be good enough for most, and it's
> also important that they're as simple as possible, and don't result in
> stuff like "my performance sucks because I turned this config option on
> once a year ago for 2 days".

  reply index

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-14  4:31 [PATCH 0/3] some prune optimizations Jeff King
2019-02-14  4:35 ` [PATCH 1/3] prune: lazily perform reachability traversal Jeff King
2019-02-14 10:54   ` Eric Sunshine
2019-02-14 11:07     ` Jeff King
2019-02-14  4:37 ` [PATCH 2/3] prune: use bitmaps for " Jeff King
2019-03-09  2:49   ` bitmaps by default? [was: prune: use bitmaps for reachability traversal] Eric Wong
2019-03-10 23:39     ` Jeff King
2019-03-12  3:13       ` [PATCH] repack: enable bitmaps by default on bare repos Eric Wong
2019-03-12  9:07         ` Ævar Arnfjörð Bjarmason
2019-03-12 10:49         ` Jeff King
2019-03-12 12:05           ` Jeff King
2019-03-13  1:51           ` Eric Wong
2019-03-13 14:54             ` Jeff King
2019-03-14  9:12               ` [PATCH v3] " Eric Wong
2019-03-14 16:02                 ` Jeff King
2019-03-15  6:21                   ` [PATCH 0/2] enable bitmap hash-cache by default Jeff King
2019-03-15  6:22                     ` [PATCH 1/2] t5310: correctly remove bitmaps for jgit test Jeff King
2019-03-15 13:25                       ` SZEDER Gábor
2019-03-15 18:36                         ` Jeff King
2019-03-15  6:25                     ` [PATCH 2/2] pack-objects: default to writing bitmap hash-cache Jeff King
2019-04-09 15:10                 ` [PATCH v3] repack: enable bitmaps by default on bare repos Ævar Arnfjörð Bjarmason
2019-04-10 22:57                   ` Jeff King
2019-04-25  7:16                     ` Junio C Hamano
2019-05-04  1:37                       ` Jeff King
2019-05-04  6:52                         ` Ævar Arnfjörð Bjarmason
2019-05-04 13:23                           ` SZEDER Gábor
2019-05-08 20:17                             ` Ævar Arnfjörð Bjarmason
2019-05-09  4:24                               ` Junio C Hamano
2019-05-07  7:45                           ` Jeff King
2019-05-07  8:12                             ` Ævar Arnfjörð Bjarmason
2019-05-08  7:11                               ` Jeff King
2019-05-08 14:20                                 ` Derrick Stolee
2019-05-08 16:13                                 ` Ævar Arnfjörð Bjarmason
2019-05-08 22:25                                   ` Jeff King
2019-05-23 11:30                     ` Jeff King
2019-05-23 12:53                       ` Derrick Stolee
2019-05-24  7:24                         ` Jeff King
2019-05-24 10:33                           ` Derrick Stolee
2019-05-23 19:26                       ` Ævar Arnfjörð Bjarmason
2019-05-24  7:27                         ` Jeff King
2019-05-24  7:55                           ` Ævar Arnfjörð Bjarmason
2019-05-24  8:26                             ` Jeff King
2019-05-24  9:01                               ` Ævar Arnfjörð Bjarmason
2019-05-24  9:29                                 ` SZEDER Gábor
2019-05-24 11:17                                   ` Ævar Arnfjörð Bjarmason
2019-05-24 11:41                                     ` SZEDER Gábor [this message]
2019-05-24 11:58                                       ` Ævar Arnfjörð Bjarmason
2019-05-24 12:34                                         ` SZEDER Gábor
2019-05-24 13:41                                           ` Ævar Arnfjörð Bjarmason
2019-05-24 11:31                       ` [PATCH] pack-bitmap: look for an uninteresting bitmap Derrick Stolee
2019-04-15 15:00   ` [PATCH 2/3] prune: use bitmaps for reachability traversal Derrick Stolee
2019-04-18 19:49     ` Jeff King
2019-04-18 20:08       ` [PATCH] t5304: add a test for pruning with bitmaps Jeff King
2019-04-20  1:01         ` Derrick Stolee
2019-04-20  3:24           ` Jeff King
2019-04-20 21:01             ` Derrick Stolee
2019-02-14  4:38 ` [PATCH 3/3] prune: check SEEN flag for reachability Jeff King

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