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From: Junio C Hamano <gitster@pobox.com>
To: Jeff King <peff@peff.net>
Cc: git@vger.kernel.org, Kyle Meyer <kyle@kyleam.com>,
	Eric Sunshine <sunshine@sunshineco.com>,
	Taylor Blau <me@ttaylorr.com>
Subject: Re: [PATCH v2] rev-list --disk-usage
Date: Tue, 09 Feb 2021 13:14:17 -0800	[thread overview]
Message-ID: <xmqq8s7x0wra.fsf@gitster.c.googlers.com> (raw)
In-Reply-To: <YCJtbmaguIW+YeAs@coredump.intra.peff.net> (Jeff King's message of "Tue, 9 Feb 2021 06:09:34 -0500")

Jeff King <peff@peff.net> writes:

> I don't know that it's really worth digging into that much, though it's
> quite possible there may be some easy wins by optimizing those memcpy
> calls. E.g., I'm not sure if the compiler ends up inlining them or not.
> If it doesn't realize that the_hash_algo->rawsz is only ever "20" or
> "32", we could perhaps help it along with specialized versions of
> hashcpy(). If somebody does want to play with it, this patch may make a
> good testbed. :)

Yuck.  That reminds me of the adventure Shawn he made in the Java
land benchmarking which one among int[5], int a,b,c,d,e, char[40] is
the most efficient way (both storage-wise and performance-wise) to
store SHA-1 hash.  I wish we didn't have to go there.

It indeed is an interesting, despite a bit sad, observation that
even with a good precomputed information, an overly heavy interface
can kill potential performance benefit.

Thanks.

  reply	other threads:[~2021-02-09 21:46 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-27 22:11 [PATCH 0/2] " Jeff King
2021-01-27 22:12 ` [PATCH 1/2] t: add --no-tag option to test_commit Jeff King
2021-01-27 22:48   ` Taylor Blau
2021-01-27 22:17 ` [PATCH 2/2] rev-list: add --disk-usage option for calculating disk usage Jeff King
2021-01-27 22:57   ` Taylor Blau
2021-01-27 23:34     ` Jeff King
2021-01-27 23:01   ` Kyle Meyer
2021-01-27 23:36     ` Jeff King
2021-01-27 23:07   ` Eric Sunshine
2021-01-27 23:39     ` Jeff King
2021-01-27 22:46 ` [PATCH 0/2] rev-list --disk-usage Taylor Blau
2021-02-09 10:52 ` [PATCH v2] " Jeff King
2021-02-09 10:52   ` [PATCH v2 1/2] t: add --no-tag option to test_commit Jeff King
2021-02-09 10:53   ` [PATCH v2 2/2] rev-list: add --disk-usage option for calculating disk usage Jeff King
2021-02-09 11:09   ` [PATCH v2] rev-list --disk-usage Jeff King
2021-02-09 21:14     ` Junio C Hamano [this message]
2021-02-10  9:38       ` Jeff King
2021-02-10  0:44   ` Junio C Hamano
2021-02-10  1:49     ` Taylor Blau
2021-02-10 10:01     ` Jeff King
2021-02-10 16:31       ` Junio C Hamano
2021-02-10 20:38         ` Jeff King
2021-02-10 23:15           ` Taylor Blau
2021-02-11 11:00             ` Jeff King
2021-02-11 12:04               ` Ævar Arnfjörð Bjarmason
2021-02-11 17:57                 ` Junio C Hamano
2021-02-17 23:31                 ` [PATCH 0/2] rev-list --disk-usage example docs Jeff King
2021-02-17 23:34                   ` [PATCH 1/2] docs/rev-list: add an examples section Jeff King
2021-02-17 23:35                   ` [PATCH 2/2] docs/rev-list: add some examples of --disk-usage Jeff King
2021-02-17 23:44                   ` [PATCH 0/2] rev-list --disk-usage example docs Taylor Blau

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