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From: Derrick Stolee <stolee@gmail.com>
To: Derrick Stolee via GitGitGadget <gitgitgadget@gmail.com>,
	git@vger.kernel.org
Cc: gitster@pobox.com, peff@peff.net, git@jeffhostetler.com,
	Derrick Stolee <derrickstolee@github.com>
Subject: Re: [PATCH 0/3] Convert index writes to use hashfile API
Date: Fri, 26 Mar 2021 16:16:05 -0400	[thread overview]
Message-ID: <01c1c74d-cc8a-0541-5193-723c41dd877c@gmail.com> (raw)
In-Reply-To: <pull.916.git.1616785928.gitgitgadget@gmail.com>

On 3/26/2021 3:12 PM, Derrick Stolee via GitGitGadget wrote:
> As I prepare some ideas on index v5, one thing that strikes me as an
> interesting direction to try is to use the chunk-format API. This would make
> our extension model extremely simple (they become optional chunks, easily
> identified by the table of contents).
> 
> But there is a huge hurdle to even starting that investigation: the index
> uses its own hashing methods, separate from the hashfile API in csum-file.c!
> 
> The internals of the algorithms are mostly identical. The only possible
> change is that the buffer sizes are different: 8KB for hashfile and 128KB in
> read-cache.c. I was unable to find a performance difference in these two
> implementations, despite testing on several repo sizes.

Of course, shortly after I send this series (thinking I've checked all the
details carefully) I notice that I was using "git update-index --really-refresh"
for testing, but what I really wanted was "git update-index --force-write".

In this case, I _do_ see a performance degradation using the hashfile API.
I will investigate whether this is just a poor implementation of the nesting
hashfile, or something else more tricky. Changing the buffer size doesn't do
the trick.

Please ignore this series for now. Sorry for the noise.

-Stolee

  parent reply	other threads:[~2021-03-26 20:17 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-26 19:12 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 ` Derrick Stolee [this message]
2021-05-17 12:24 ` [PATCH v2 0/4] Convert index writes to use hashfile API 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
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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