From: Junio C Hamano <gitster@pobox.com>
To: Taylor Blau <me@ttaylorr.com>
Cc: Jeff King <peff@peff.net>,
git@vger.kernel.org, dstolee@microsoft.com, jrnieder@gmail.com
Subject: Re: [PATCH v2 1/8] packfile: prepare for the existence of '*.rev' files
Date: Mon, 25 Jan 2021 11:04:33 -0800 [thread overview]
Message-ID: <xmqqy2ggyh1a.fsf@gitster.c.googlers.com> (raw)
In-Reply-To: <YA8DlQwSzNZXq+AU@nand.local> (Taylor Blau's message of "Mon, 25 Jan 2021 12:44:53 -0500")
Taylor Blau <me@ttaylorr.com> writes:
>> Thinking out loud a bit: a .rev file means we're spending an extra map
>> per pack (but not a descriptor, since we close after mmap). And like the
>> .idx files (but unlike .pack file maps), we don't keep track of these
>> and try to close them when under memory pressure. I think that's
>> probably OK in terms of bytes. It may mean running up against operating
>> system number-of-mmap limits more quickly ...
>> ...
>> > if (ends_with(name, ".idx"))
>> > return 3;
>> > - return 4;
>> > + if (ends_with(name, ".rev"))
>> > + return 4;
>> > + return 5;
>> > }
>>
>> Probably not super important, but: should the .idx file still come last
>> here? Simultaneous readers won't start using the pack until the .idx
>> file is present. We'd probably prefer they see the whole thing
>> atomically, than see a .idx missing its .rev (they won't ever produce a
>> wrong answer, but they'll generate the in-core revindex on the fly when
>> they don't need to).
At some point, we may want to
- introduce .idx version 3 that is more extensible, so that the
reverse info is included in one of its chunks;
- make the .rev data for all packs stored as a chunk in .midx, so
we can first check with .midx and not open any .rev files.
either of which would reduce the numberfrom 30k down to 10k ;-)
next prev parent reply other threads:[~2021-01-25 19:09 UTC|newest]
Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-08 18:19 [PATCH 0/8] pack-revindex: introduce on-disk '.rev' format Taylor Blau
2021-01-08 18:19 ` [PATCH 1/8] packfile: prepare for the existence of '*.rev' files Taylor Blau
2021-01-08 18:20 ` [PATCH 2/8] pack-write.c: prepare to write 'pack-*.rev' files Taylor Blau
2021-01-08 18:20 ` [PATCH 3/8] builtin/index-pack.c: write reverse indexes Taylor Blau
2021-01-08 18:20 ` [PATCH 4/8] builtin/pack-objects.c: respect 'pack.writeReverseIndex' Taylor Blau
2021-01-08 18:20 ` [PATCH 5/8] Documentation/config/pack.txt: advertise 'pack.writeReverseIndex' Taylor Blau
2021-01-08 18:20 ` [PATCH 6/8] t: prepare for GIT_TEST_WRITE_REV_INDEX Taylor Blau
2021-01-12 17:11 ` Ævar Arnfjörð Bjarmason
2021-01-12 18:40 ` Taylor Blau
2021-01-08 18:20 ` [PATCH 7/8] t: support GIT_TEST_WRITE_REV_INDEX Taylor Blau
2021-01-12 16:49 ` Derrick Stolee
2021-01-12 17:34 ` Taylor Blau
2021-01-12 17:18 ` Ævar Arnfjörð Bjarmason
2021-01-12 17:39 ` Derrick Stolee
2021-01-12 18:17 ` Taylor Blau
2021-01-08 18:20 ` [PATCH 8/8] pack-revindex: ensure that on-disk reverse indexes are given precedence Taylor Blau
2021-01-13 22:28 ` [PATCH v2 0/8] pack-revindex: introduce on-disk '.rev' format Taylor Blau
2021-01-13 22:28 ` [PATCH v2 1/8] packfile: prepare for the existence of '*.rev' files Taylor Blau
2021-01-14 7:22 ` Junio C Hamano
2021-01-14 12:07 ` Derrick Stolee
2021-01-14 19:57 ` Jeff King
2021-01-14 18:28 ` Taylor Blau
2021-01-14 7:26 ` Junio C Hamano
2021-01-14 18:13 ` Taylor Blau
2021-01-14 20:57 ` Junio C Hamano
2021-01-22 22:54 ` Jeff King
2021-01-25 17:44 ` Taylor Blau
2021-01-25 18:27 ` Jeff King
2021-01-25 19:04 ` Junio C Hamano [this message]
2021-01-25 19:23 ` Taylor Blau
2021-01-13 22:28 ` [PATCH v2 2/8] pack-write.c: prepare to write 'pack-*.rev' files Taylor Blau
2021-01-22 23:24 ` Jeff King
2021-01-25 19:15 ` Taylor Blau
2021-01-26 21:43 ` Jeff King
2021-01-13 22:28 ` [PATCH v2 3/8] builtin/index-pack.c: write reverse indexes Taylor Blau
2021-01-22 23:53 ` Jeff King
2021-01-25 20:03 ` Taylor Blau
2021-01-13 22:28 ` [PATCH v2 4/8] builtin/pack-objects.c: respect 'pack.writeReverseIndex' Taylor Blau
2021-01-22 23:57 ` Jeff King
2021-01-23 0:08 ` Jeff King
2021-01-25 20:21 ` Taylor Blau
2021-01-25 20:50 ` Jeff King
2021-01-13 22:28 ` [PATCH v2 5/8] Documentation/config/pack.txt: advertise 'pack.writeReverseIndex' Taylor Blau
2021-01-13 22:28 ` [PATCH v2 6/8] t: prepare for GIT_TEST_WRITE_REV_INDEX Taylor Blau
2021-01-13 22:28 ` [PATCH v2 7/8] t: support GIT_TEST_WRITE_REV_INDEX Taylor Blau
2021-01-13 22:28 ` [PATCH v2 8/8] pack-revindex: ensure that on-disk reverse indexes are given precedence Taylor Blau
2021-01-25 23:37 ` [PATCH v3 00/10] pack-revindex: introduce on-disk '.rev' format Taylor Blau
2021-01-25 23:37 ` [PATCH v3 01/10] packfile: prepare for the existence of '*.rev' files Taylor Blau
2021-01-29 0:27 ` Jeff King
2021-01-29 1:14 ` Taylor Blau
2021-01-30 8:39 ` Jeff King
2021-01-25 23:37 ` [PATCH v3 02/10] pack-write.c: prepare to write 'pack-*.rev' files Taylor Blau
2021-01-25 23:37 ` [PATCH v3 03/10] builtin/index-pack.c: allow stripping arbitrary extensions Taylor Blau
2021-01-29 0:28 ` Jeff King
2021-01-29 1:15 ` Taylor Blau
2021-01-25 23:37 ` [PATCH v3 04/10] builtin/index-pack.c: write reverse indexes Taylor Blau
2021-01-25 23:37 ` [PATCH v3 05/10] builtin/pack-objects.c: respect 'pack.writeReverseIndex' Taylor Blau
2021-01-25 23:37 ` [PATCH v3 06/10] Documentation/config/pack.txt: advertise 'pack.writeReverseIndex' Taylor Blau
2021-01-29 0:30 ` Jeff King
2021-01-29 1:17 ` Taylor Blau
2021-01-30 8:41 ` Jeff King
2021-01-25 23:37 ` [PATCH v3 07/10] t: prepare for GIT_TEST_WRITE_REV_INDEX Taylor Blau
2021-01-29 0:45 ` Jeff King
2021-01-29 1:09 ` Eric Sunshine
2021-01-29 1:21 ` Taylor Blau
2021-01-30 8:43 ` Jeff King
2021-01-29 2:42 ` Junio C Hamano
2021-01-25 23:37 ` [PATCH v3 08/10] t: support GIT_TEST_WRITE_REV_INDEX Taylor Blau
2021-01-29 0:47 ` Jeff King
2021-01-25 23:37 ` [PATCH v3 09/10] pack-revindex: ensure that on-disk reverse indexes are given precedence Taylor Blau
2021-01-29 0:53 ` Jeff King
2021-01-29 1:25 ` Taylor Blau
2021-01-30 8:46 ` Jeff King
2021-01-25 23:37 ` [PATCH v3 10/10] t5325: check both on-disk and in-memory reverse index Taylor Blau
2021-01-29 1:04 ` Jeff King
2021-01-29 1:05 ` Jeff King
2021-01-29 1:32 ` Taylor Blau
2021-01-30 8:47 ` Jeff King
2021-01-26 2:36 ` [PATCH v3 00/10] pack-revindex: introduce on-disk '.rev' format Junio C Hamano
2021-01-26 2:49 ` Taylor Blau
2021-01-29 1:06 ` Jeff King
2021-01-29 1:34 ` Taylor Blau
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