git@vger.kernel.org list mirror (unofficial, one of many)
 help / color / mirror / code / Atom feed
From: Taylor Blau <me@ttaylorr.com>
To: "SZEDER Gábor" <szeder.dev@gmail.com>
Cc: Taylor Blau <me@ttaylorr.com>,
	git@vger.kernel.org, peff@peff.net, dstolee@microsoft.com,
	gitster@pobox.com
Subject: Re: [PATCH v3 14/14] builtin/commit-graph.c: introduce '--max-new-filters=<n>'
Date: Thu, 3 Sep 2020 12:35:44 -0400	[thread overview]
Message-ID: <20200903163513.GA6521@nand.local> (raw)
In-Reply-To: <20200818222329.GC29528@szeder.dev>

On Wed, Aug 19, 2020 at 12:23:29AM +0200, SZEDER Gábor wrote:
> On Tue, Aug 11, 2020 at 04:52:14PM -0400, Taylor Blau wrote:
> > Introduce a command-line flag and configuration variable to fill in the
> > 'max_new_filters' variable introduced by the previous patch.
>
> 'max_new_filters' is introduced in this patch.
>
> > The command-line option '--max-new-filters' takes precedence over
> > 'commitGraph.maxNewFilters', which is the default value.
>
> What "filters"?  While misnamed, the '--changed-paths' options did a
> good job at hiding the implementation detail that we use Bloom filters
> to speed up pathspec-limited revision walks; as far as I remember this
> was a conscious design decision.  Including "filter" in the name of
> the option and corresponding config variable goes against this
> decision.  Furthermore, by not being specific we might end up in abad
> situation when adding some other filters to the commit-graph format.
> Unfortunately, I can't offhand propose a better option name, all my
> ideas were horrible.

I don't disagree, but I can't come up with a better name either.
maxNewChangedPaths? maxNewSomething? I don't know. Usually I think
exposing this sort of detail is smelly, but I'm not so bothered by it
here. Similarly, this thread has been around for a while, and nobody
else has suggested a better name, so, I'm inclined to keep it.

> > +With the `--max-new-filters=<n>` option, generate at most `n` new Bloom
> > +filters (if `--changed-paths` is specified). If `n` is `-1`, no limit is
> > +enforced. Overrides the `commitGraph.maxNewFilters` configuration.
>
> I think this description should also detail what happens with those
> commits for which no modified path Bloom filters are calculated, and
> which commands will calculate them (even implicitly).

OK, sure.

> >  static int get_bloom_filter_large_in_graph(struct commit_graph *g,
> > -					   const struct commit *c)
> > +					   const struct commit *c,
> > +					   uint32_t max_changed_paths)
> >  {
> >  	uint32_t graph_pos = commit_graph_position(c);
> >  	if (graph_pos == COMMIT_NOT_FROM_GRAPH)
> > @@ -965,6 +966,17 @@ static int get_bloom_filter_large_in_graph(struct commit_graph *g,
> >
> >  	if (!(g && g->bloom_large))
> >  		return 0;
> > +	if (g->bloom_filter_settings->max_changed_paths != max_changed_paths) {
> > +		/*
> > +		 * Force all commits which are subject to a different
> > +		 * 'max_changed_paths' limit to be recomputed from scratch.
> > +		 *
> > +		 * Note that this could likely be improved, but is ignored since
> > +		 * all real-world graphs set the maximum number of changed paths
> > +		 * at 512.
>
> I don't understand what the second part of this comment is trying to
> say; and real-world graphs might very well contain Bloom filters with
> more than 512 modified paths, because the applying that limit was
> buggy.

I'm trying to say that there is room for us to improve when we do and
don't recompute filters when the limit on the number of changed paths
deviates between layers, but that such deviations don't currently exist
in the wild.

Bugs are another thing, but we can't tell that they exist without
recomputing every filter.

Thanks,
Taylor

  reply	other threads:[~2020-09-03 16:35 UTC|newest]

Thread overview: 117+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-03 18:57 [PATCH 00/10] more miscellaneous Bloom filter improvements Taylor Blau
2020-08-03 18:57 ` [PATCH 01/10] commit-graph: introduce 'get_bloom_filter_settings()' Taylor Blau
2020-08-04  7:24   ` Jeff King
2020-08-04 20:08     ` Taylor Blau
2020-08-03 18:57 ` [PATCH 02/10] commit-graph: pass a 'struct repository *' in more places Taylor Blau
2020-08-03 18:57 ` [PATCH 03/10] t4216: use an '&&'-chain Taylor Blau
2020-08-03 18:57 ` [PATCH 04/10] t/helper/test-read-graph.c: prepare repo settings Taylor Blau
2020-08-03 18:57 ` [PATCH 05/10] commit-graph: respect 'commitgraph.readChangedPaths' Taylor Blau
2020-08-03 18:57 ` [PATCH 06/10] commit-graph.c: sort index into commits list Taylor Blau
2020-08-04 12:31   ` Derrick Stolee
2020-08-04 20:10     ` Taylor Blau
2020-08-03 18:57 ` [PATCH 07/10] commit-graph: add large-filters bitmap chunk Taylor Blau
2020-08-03 18:59   ` Taylor Blau
2020-08-04 12:57   ` Derrick Stolee
2020-08-03 18:57 ` [PATCH 08/10] bloom: split 'get_bloom_filter()' in two Taylor Blau
2020-08-04 13:00   ` Derrick Stolee
2020-08-04 20:12     ` Taylor Blau
2020-08-03 18:57 ` [PATCH 09/10] commit-graph: rename 'split_commit_graph_opts' Taylor Blau
2020-08-03 18:57 ` [PATCH 10/10] builtin/commit-graph.c: introduce '--max-new-filters=<n>' Taylor Blau
2020-08-04 13:03   ` Derrick Stolee
2020-08-04 20:14     ` Taylor Blau
2020-08-05 17:01 ` [PATCH v2 00/14] more miscellaneous Bloom filter improvements Taylor Blau
2020-08-05 17:01   ` [PATCH v2 01/14] commit-graph: introduce 'get_bloom_filter_settings()' Taylor Blau
2020-08-05 17:02   ` [PATCH v2 02/14] t4216: use an '&&'-chain Taylor Blau
2020-08-05 17:02   ` [PATCH v2 03/14] commit-graph: pass a 'struct repository *' in more places Taylor Blau
2020-08-05 17:02   ` [PATCH v2 04/14] t/helper/test-read-graph.c: prepare repo settings Taylor Blau
2020-08-05 17:02   ` [PATCH v2 05/14] commit-graph: respect 'commitGraph.readChangedPaths' Taylor Blau
2020-08-05 17:02   ` [PATCH v2 06/14] commit-graph.c: store maximum changed paths Taylor Blau
2020-08-05 17:02   ` [PATCH v2 07/14] bloom: split 'get_bloom_filter()' in two Taylor Blau
2020-08-05 17:02   ` [PATCH v2 08/14] bloom: use provided 'struct bloom_filter_settings' Taylor Blau
2020-08-05 17:02   ` [PATCH v2 09/14] bloom/diff: properly short-circuit on max_changes Taylor Blau
2020-08-05 17:02   ` [PATCH v2 10/14] commit-graph.c: sort index into commits list Taylor Blau
2020-08-05 17:02   ` [PATCH v2 11/14] csum-file.h: introduce 'hashwrite_be64()' Taylor Blau
2020-08-05 17:02   ` [PATCH v2 12/14] commit-graph: add large-filters bitmap chunk Taylor Blau
2020-08-05 21:01     ` Junio C Hamano
2020-08-05 21:17       ` Taylor Blau
2020-08-05 22:21         ` Junio C Hamano
2020-08-05 22:25           ` Taylor Blau
2020-08-11 13:48             ` Taylor Blau
2020-08-11 18:59               ` Junio C Hamano
2020-08-05 17:03   ` [PATCH v2 13/14] commit-graph: rename 'split_commit_graph_opts' Taylor Blau
2020-08-05 17:03   ` [PATCH v2 14/14] builtin/commit-graph.c: introduce '--max-new-filters=<n>' Taylor Blau
2020-08-11 20:51 ` [PATCH v3 00/14] more miscellaneous Bloom filter improvements Taylor Blau
2020-08-11 20:51   ` [PATCH v3 01/14] commit-graph: introduce 'get_bloom_filter_settings()' Taylor Blau
2020-08-11 21:18     ` SZEDER Gábor
2020-08-11 21:21       ` Taylor Blau
2020-08-11 21:27         ` SZEDER Gábor
2020-08-11 21:34           ` Taylor Blau
2020-08-11 23:55             ` SZEDER Gábor
2020-08-12 11:48               ` Derrick Stolee
2020-08-14 20:17                 ` Taylor Blau
2020-08-11 20:51   ` [PATCH v3 02/14] t4216: use an '&&'-chain Taylor Blau
2020-08-11 20:51   ` [PATCH v3 03/14] commit-graph: pass a 'struct repository *' in more places Taylor Blau
2020-08-11 20:51   ` [PATCH v3 04/14] t/helper/test-read-graph.c: prepare repo settings Taylor Blau
2020-08-11 20:51   ` [PATCH v3 05/14] commit-graph: respect 'commitGraph.readChangedPaths' Taylor Blau
2020-08-11 20:51   ` [PATCH v3 06/14] commit-graph.c: store maximum changed paths Taylor Blau
2020-08-11 20:51   ` [PATCH v3 07/14] bloom: split 'get_bloom_filter()' in two Taylor Blau
2020-08-11 20:51   ` [PATCH v3 11/14] csum-file.h: introduce 'hashwrite_be64()' Taylor Blau
2020-08-11 20:51   ` [PATCH v3 08/14] bloom: use provided 'struct bloom_filter_settings' Taylor Blau
2020-08-11 20:51   ` [PATCH v3 09/14] bloom/diff: properly short-circuit on max_changes Taylor Blau
2020-08-11 20:52   ` [PATCH v3 10/14] commit-graph.c: sort index into commits list Taylor Blau
2020-08-11 20:52   ` [PATCH v3 12/14] commit-graph: add large-filters bitmap chunk Taylor Blau
2020-08-11 21:11     ` Derrick Stolee
2020-08-11 21:18       ` Taylor Blau
2020-08-11 22:05         ` Taylor Blau
2020-08-19 13:35     ` SZEDER Gábor
2020-09-02 20:23       ` Taylor Blau
2020-09-01 14:35     ` SZEDER Gábor
2020-09-02 20:40       ` Taylor Blau
2020-08-11 20:52   ` [PATCH v3 13/14] commit-graph: rename 'split_commit_graph_opts' Taylor Blau
2020-08-19  9:56     ` SZEDER Gábor
2020-09-02 21:02       ` Taylor Blau
2020-08-11 20:52   ` [PATCH v3 14/14] builtin/commit-graph.c: introduce '--max-new-filters=<n>' Taylor Blau
2020-08-12 11:49     ` SZEDER Gábor
2020-08-14 20:20       ` Taylor Blau
2020-08-17 22:50         ` SZEDER Gábor
2020-09-02 21:03           ` Taylor Blau
2020-08-12 12:29     ` Derrick Stolee
2020-08-14 20:10       ` Taylor Blau
2020-08-18 22:23     ` SZEDER Gábor
2020-09-03 16:35       ` Taylor Blau [this message]
2020-08-19  8:20     ` SZEDER Gábor
2020-09-03 16:42       ` Taylor Blau
2020-09-04  8:50         ` SZEDER Gábor
2020-09-01 14:36     ` SZEDER Gábor
2020-09-03 18:49       ` Taylor Blau
2020-09-03 21:45   ` [PATCH v3 00/14] more miscellaneous Bloom filter improvements Junio C Hamano
2020-09-03 22:33     ` Taylor Blau
2020-09-03 22:45 ` [PATCH v4 " Taylor Blau
2020-09-03 22:46   ` [PATCH v4 01/14] commit-graph: introduce 'get_bloom_filter_settings()' Taylor Blau
2020-09-03 22:46   ` [PATCH v4 02/14] t4216: use an '&&'-chain Taylor Blau
2020-09-03 22:46   ` [PATCH v4 03/14] commit-graph: pass a 'struct repository *' in more places Taylor Blau
2020-09-03 22:46   ` [PATCH v4 04/14] t/helper/test-read-graph.c: prepare repo settings Taylor Blau
2020-09-03 22:46   ` [PATCH v4 05/14] commit-graph: respect 'commitGraph.readChangedPaths' Taylor Blau
2020-09-03 22:46   ` [PATCH v4 06/14] commit-graph.c: store maximum changed paths Taylor Blau
2020-09-03 22:46   ` [PATCH v4 07/14] bloom: split 'get_bloom_filter()' in two Taylor Blau
2020-09-05 17:22     ` Jakub Narębski
2020-09-05 17:38       ` Taylor Blau
2020-09-05 17:50         ` Jakub Narębski
2020-09-05 18:01           ` Taylor Blau
2020-09-05 18:18             ` Jakub Narębski
2020-09-05 18:38               ` Taylor Blau
2020-09-05 18:55                 ` Taylor Blau
2020-09-05 19:04                   ` SZEDER Gábor
2020-09-05 19:49                     ` Taylor Blau
2020-09-06 21:52                       ` Junio C Hamano
2020-09-03 22:46   ` [PATCH v4 08/14] bloom: use provided 'struct bloom_filter_settings' Taylor Blau
2020-09-03 22:46   ` [PATCH v4 09/14] bloom/diff: properly short-circuit on max_changes Taylor Blau
2020-09-03 22:46   ` [PATCH v4 10/14] commit-graph.c: sort index into commits list Taylor Blau
2020-09-03 22:46   ` [PATCH v4 11/14] csum-file.h: introduce 'hashwrite_be64()' Taylor Blau
2020-09-04 20:18     ` René Scharfe
2020-09-04 20:22       ` Taylor Blau
2020-09-03 22:46   ` [PATCH v4 12/14] commit-graph: add large-filters bitmap chunk Taylor Blau
2020-09-03 22:46   ` [PATCH v4 13/14] commit-graph: rename 'split_commit_graph_opts' Taylor Blau
2020-09-04 15:20     ` Taylor Blau
2020-09-03 22:47   ` [PATCH v4 14/14] builtin/commit-graph.c: introduce '--max-new-filters=<n>' Taylor Blau
2020-09-04 14:39   ` [PATCH v4 00/14] more miscellaneous Bloom filter improvements Derrick Stolee

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

  List information: http://vger.kernel.org/majordomo-info.html

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200903163513.GA6521@nand.local \
    --to=me@ttaylorr.com \
    --cc=dstolee@microsoft.com \
    --cc=git@vger.kernel.org \
    --cc=gitster@pobox.com \
    --cc=peff@peff.net \
    --cc=szeder.dev@gmail.com \
    --subject='Re: [PATCH v3 14/14] builtin/commit-graph.c: introduce '\''--max-new-filters=<n>'\''' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Code repositories for project(s) associated with this inbox:

	https://80x24.org/mirrors/git.git

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).