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From: Jeff King <peff@peff.net>
To: Derrick Stolee <stolee@gmail.com>
Cc: git@vger.kernel.org
Subject: Re: [PATCH 3/6] t/perf: add infrastructure for measuring sizes
Date: Wed, 22 Aug 2018 11:31:04 -0400	[thread overview]
Message-ID: <20180822153104.GE32630@sigill.intra.peff.net> (raw)
In-Reply-To: <b071f6a2-2403-0bbb-72a5-695f8c4e724d@gmail.com>

On Wed, Aug 22, 2018 at 09:40:55AM -0400, Derrick Stolee wrote:

> On 8/21/2018 3:06 PM, Jeff King wrote:
> > The main objective of scripts in the perf framework is to
> > run "test_perf", which measures the time it takes to run
> > some operation. However, it can also be interesting to see
> > the change in the output size of certain operations.
> > 
> > This patch introduces test_size, which records a single
> > numeric output from the test and shows it in the aggregated
> > output (with pretty printing and relative size comparison).
> 
> I'm interested in exploring this test_size mechanism. The other area that
> could benefit from size testing is 'git repack', but I don't have any plans
> to change our compression or delta strategies. If we _did_ look into that,
> then using test_size would be a natural fit.

Yeah, I agree it would be a good tool for showing off improvements
there.

It may also be useful for catching regressions in topics that are trying
to speed things up, but _don't_ intend to change the size. We could even
do that proactively now. I.e., something like:

  test_perf 'repack' 'git repack -adf'
  test_size 'pack size' 'wc -c <.git/objects/pack/*.pack'

just to see if it ever changes.  But I suspect its usefulness may depend
on how you are packing (e.g., is "-f" more likely to catch issues than
without?).

The new tests I added in this series cover packs created for fetches.
There's no guarantee that will overlap with the behavior of an on-disk
repack, but at least we have some generic coverage of pack-objects
output sizes now. Absent any suspicion of a regression for a particular
case, that's probably an acceptable canary in the coal mine.

-Peff

  reply	other threads:[~2018-08-22 15:31 UTC|newest]

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-21 18:41 [PATCH] test-tool.h: include git-compat-util.h Jeff King
2018-08-21 19:03 ` Junio C Hamano
2018-08-21 19:06 ` [PATCH 1/6] t/perf: factor boilerplate out of test_perf Jeff King
2018-08-21 19:06 ` [PATCH 2/6] t/perf: factor out percent calculations Jeff King
2018-08-21 19:06 ` [PATCH 3/6] t/perf: add infrastructure for measuring sizes Jeff King
2018-08-22 13:40   ` Derrick Stolee
2018-08-22 15:31     ` Jeff King [this message]
2018-08-21 19:06 ` [PATCH 4/6] t/perf: add perf tests for fetches from a bitmapped server Jeff King
2018-08-21 19:07 ` [PATCH 5/6] pack-bitmap: save "have" bitmap from walk Jeff King
2018-08-21 19:47   ` Derrick Stolee
2018-08-21 19:54     ` Jeff King
2018-08-31 15:23   ` Ævar Arnfjörð Bjarmason
2018-08-31 22:55     ` Jeff King
2018-09-01  7:41       ` [PATCH 0/4] un-breaking pack-objects with bitmaps Jeff King
2018-09-01  7:44         ` [PATCH 1/4] bitmap_has_sha1_in_uninteresting(): drop BUG check Jeff King
2018-09-01  7:48         ` [PATCH 2/4] t5310: test delta reuse with bitmaps Jeff King
2018-09-01  8:03           ` Jeff King
2018-09-01 20:29             ` Ævar Arnfjörð Bjarmason
2018-09-01 22:46               ` Ben Peart
2018-09-02  5:51               ` Jeff King
2018-09-04 19:05             ` Stefan Beller
2018-09-04 19:45               ` Junio C Hamano
2018-09-04 20:02               ` Jeff King
2018-09-01  7:49         ` [PATCH 3/4] traverse_bitmap_commit_list(): don't free result Jeff King
2018-09-01  7:50         ` [PATCH 4/4] pack-bitmap: drop "loaded" flag Jeff King
2018-09-04 19:30         ` [PATCH 0/4] un-breaking pack-objects with bitmaps Stefan Beller
2018-09-04 20:03           ` Jeff King
2018-09-08  6:43         ` Ævar Arnfjörð Bjarmason
2018-09-10 16:53           ` Junio C Hamano
2018-09-10 18:48             ` Jeff King
2018-09-10 19:23               ` Junio C Hamano
2018-08-21 19:07 ` [PATCH 6/6] pack-objects: reuse on-disk deltas for thin "have" objects Jeff King
2018-08-21 19:43   ` Junio C Hamano
2018-08-21 19:50     ` Junio C Hamano
2018-08-21 20:07       ` Jeff King
2018-08-21 20:14         ` Jeff King
2018-08-21 20:52           ` Junio C Hamano
2018-08-21 21:30             ` Jeff King
2018-08-21 20:57         ` Junio C Hamano
2018-08-21 21:32           ` Jeff King
2018-08-23  0:43           ` [PATCH 0/9] trailer-parsing false positives Jeff King
2018-08-23  0:44             ` [PATCH 1/9] trailer: use size_t for string offsets Jeff King
2018-08-23  0:45             ` [PATCH 2/9] trailer: use size_t for iterating trailer list Jeff King
2018-08-23  0:46             ` [PATCH 3/9] trailer: pass process_trailer_opts to trailer_info_get() Jeff King
2018-08-23  0:48             ` [PATCH 4/9] interpret-trailers: tighten check for "---" patch boundary Jeff King
2018-08-23  0:49             ` [PATCH 5/9] interpret-trailers: allow suppressing "---" divider Jeff King
2018-08-23  0:50             ` [PATCH 6/9] pretty, ref-filter: format %(trailers) with no_divider option Jeff King
2018-08-23  0:50             ` [PATCH 7/9] sequencer: ignore "---" divider when parsing trailers Jeff King
2018-08-23  0:50             ` [PATCH 8/9] append_signoff: use size_t for string offsets Jeff King
2018-08-23  0:51             ` [PATCH 9/9] sequencer: handle ignore_footer when parsing trailers Jeff King
2018-08-23 18:30             ` [PATCH 0/9] trailer-parsing false positives Junio C Hamano
2018-08-24  7:26               ` Jeff King
2018-08-21 20:00     ` [PATCH 6/6] pack-objects: reuse on-disk deltas for thin "have" objects Jeff King
  -- strict thread matches above, loose matches on Subject: below --
2018-08-17 20:54 [PATCH 0/6] reuse on-disk deltas for fetches with bitmaps Jeff King
2018-08-17 20:56 ` [PATCH 3/6] t/perf: add infrastructure for measuring sizes Jeff King
2014-03-26  7:22 [PATCH/RFC 0/6] reuse deltas found by bitmaps Jeff King
2014-03-26  7:22 ` [PATCH 3/6] t/perf: add infrastructure for measuring sizes Jeff King

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