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From: Junio C Hamano <gitster@pobox.com>
To: "Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com>
Cc: git@vger.kernel.org, peff@peff.net, stolee@gmail.com,
	git@jeffhostetler.com, Derrick Stolee <derrickstolee@github.com>,
	Derrick Stolee <dstolee@microsoft.com>
Subject: Re: [PATCH v2 3/4] read-cache: use hashfile instead of git_hash_ctx
Date: Tue, 18 May 2021 07:13:57 +0900	[thread overview]
Message-ID: <xmqqfsyl57q2.fsf@gitster.g> (raw)
In-Reply-To: <b94172ccf5e91fe59a1d32774dbec23e624f1135.1621254292.git.gitgitgadget@gmail.com> (Derrick Stolee via GitGitGadget's message of "Mon, 17 May 2021 12:24:51 +0000")

"Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com> writes:

> ...
> mult-pack-indexes, and commit-graphs. Therefore, it seems prudent to

multi-pack, I would say.

> There are still some remaining: the extension headers are hashed for use

some remaining what?  I first read an unwritten word as "issues",
but I think the answer is "uses of git_hash_ctx".

> in the End of Index Entries (EOIE) extension. This use of the
> git_hash_ctx is left as-is. There are multiple reasons to not use a
> hashfile here, including ...

> In addition to the test suite passing, I computed indexes using the
> previous binaries and the binaries compiled after this change, and found
> the index data to be exactly equal. Finally, I did extensive performance
> testing of "git update-index --force-write" on repos of various sizes,
> including one with over 2 million paths at HEAD. These tests
> demonstrated less than 1% difference in behavior, so the performance
> should be considered identical.

Hmph, does that mean 128k buffer is overkill and if we wanted to
unify the buffer sizes we should have used 8k instead?

Wait, the removal of fsync has made things faster in general, hasn't
it?  Did something else degrade performance to cancel that gain?

The patch looks an obvious improvement.  What was open-coded in
longhand is now a well structured series of API calls and the result
is much easier to follow and maintain.

Thanks.

  reply	other threads:[~2021-05-17 22:14 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-26 19:12 [PATCH 0/3] Convert index writes to use hashfile API Derrick Stolee via GitGitGadget
2021-03-26 19:12 ` [PATCH 1/3] csum-file: add nested_hashfile() Derrick Stolee via GitGitGadget
2021-03-26 19:12 ` [PATCH 2/3] read-cache: use hashfile instead of git_hash_ctx Derrick Stolee via GitGitGadget
2021-03-29 15:04   ` Derrick Stolee
2021-03-29 19:10     ` Derrick Stolee
2021-03-26 19:12 ` [PATCH 3/3] read-cache: delete unused hashing methods Derrick Stolee via GitGitGadget
2021-03-26 20:16 ` [PATCH 0/3] Convert index writes to use hashfile API Derrick Stolee
2021-05-17 12:24 ` [PATCH v2 0/4] " Derrick Stolee via GitGitGadget
2021-05-17 12:24   ` [PATCH v2 1/4] hashfile: use write_in_full() Derrick Stolee via GitGitGadget
2021-05-17 12:24   ` [PATCH v2 2/4] csum-file.h: increase hashfile buffer size Derrick Stolee via GitGitGadget
2021-05-17 21:54     ` Junio C Hamano
2021-05-18  7:33       ` Jeff King
2021-05-18 14:44         ` Derrick Stolee
2021-05-18  7:31     ` Jeff King
2021-05-18  7:42       ` Jeff King
2021-05-17 12:24   ` [PATCH v2 3/4] read-cache: use hashfile instead of git_hash_ctx Derrick Stolee via GitGitGadget
2021-05-17 22:13     ` Junio C Hamano [this message]
2021-05-18 14:16       ` Derrick Stolee
2021-05-17 12:24   ` [PATCH v2 4/4] read-cache: delete unused hashing methods Derrick Stolee via GitGitGadget
2021-05-18 18:32   ` [PATCH v3 0/4] Convert index writes to use hashfile API Derrick Stolee via GitGitGadget
2021-05-18 18:32     ` [PATCH v3 1/4] hashfile: use write_in_full() Derrick Stolee via GitGitGadget
2021-05-18 18:32     ` [PATCH v3 2/4] csum-file.h: increase hashfile buffer size Derrick Stolee via GitGitGadget
2021-11-25 12:14       ` t4216-log-bloom.sh fails with -v (but not --verbose-log) Ævar Arnfjörð Bjarmason
2021-11-26  4:08         ` Jeff King
2021-11-29 13:49           ` Derrick Stolee
2021-05-18 18:32     ` [PATCH v3 3/4] read-cache: use hashfile instead of git_hash_ctx Derrick Stolee via GitGitGadget
2021-05-18 18:32     ` [PATCH v3 4/4] read-cache: delete unused hashing methods Derrick Stolee via GitGitGadget

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