From: Derrick Stolee <stolee@gmail.com>
To: Jeff King <peff@peff.net>, Junio C Hamano <gitster@pobox.com>
Cc: Derrick Stolee <dstolee@microsoft.com>,
git@vger.kernel.org, git@jeffhostetler.com
Subject: Re: [PATCH v2 1/5] test-list-objects: List a subset of object ids
Date: Thu, 5 Oct 2017 08:39:42 -0400 [thread overview]
Message-ID: <6222f65a-c518-74a4-9df4-89bf997425cb@gmail.com> (raw)
In-Reply-To: <20171005100001.do5m4zhexcsltvw7@sigill.intra.peff.net>
On 10/5/2017 6:00 AM, Jeff King wrote:
> On Thu, Oct 05, 2017 at 06:48:10PM +0900, Junio C Hamano wrote:
>
>> Jeff King <peff@peff.net> writes:
>>
>>> This is weirdly specific. Can we accomplish the same thing with existing
>>> tools?
>>>
>>> E.g., could:
>>>
>>> git cat-file --batch-all-objects --batch-check='%(objectname)' |
>>> shuffle |
>>> head -n 100
>>>
>>> do the same thing?
>>>
>>> I know that "shuffle" isn't available everywhere, but I'd much rather
>>> see us fill in portability gaps in a general way, rather than
>>> introducing one-shot C code that needs to be maintained (and you
>>> wouldn't _think_ that t/helper programs need much maintenance, but try
>>> perusing "git log t/helper" output; they have to adapt to the same
>>> tree-wide changes as the rest of the code).
>> I was thinking about this a bit more, and came to the conclusion
>> that "sort -R" and "shuf" are wrong tools to use. We would want to
>> measure with something close to real world workload. for example,
>> letting
>>
>> git rev-list --all --objects
>>
>> produce the listof objects in traversal order (i.e. this is very
>> similar to the order in which "git log -p" needs to access the
>> objects) and chomping at the number of sample objects you need in
>> your test would give you such a list.
> Actually, I'd just as soon see timings for "git log --format=%h" or "git
> log --raw", as opposed to patches 1 and 2.
>
> You won't see a 90% speedup there, but you will see the actual
> improvement that real-world users are going to experience, which is way
> more important, IMHO.
>
> -Peff
Thanks for thinking hard about this.
For some real-user context: Some engineers using Git for the Windows
repo were seeing extremely slow commands, such as 'fetch' or 'commit',
and when we took a trace we saw most of the time spinning in this
abbreviation code. Our workaround so far has been to set core.abbrev=40.
I'll run some perf numbers for these commands you recommend, and also
see if I can replicate some of the pain points that triggered this
change using the Linux repo.
Thanks,
-Stolee
next prev parent reply other threads:[~2017-10-05 12:39 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-25 9:54 [PATCH v2 0/5] Improve abbreviation disambiguation Derrick Stolee
2017-09-25 9:54 ` [PATCH v2 1/5] test-list-objects: List a subset of object ids Derrick Stolee
2017-09-26 9:24 ` Junio C Hamano
2017-10-05 8:42 ` Jeff King
2017-10-05 9:48 ` Junio C Hamano
2017-10-05 10:00 ` Jeff King
2017-10-05 10:16 ` Junio C Hamano
2017-10-05 12:39 ` Derrick Stolee [this message]
2017-10-06 14:11 ` Jeff King
2017-10-07 19:12 ` Derrick Stolee
2017-10-07 19:33 ` Jeff King
2017-10-08 1:46 ` Junio C Hamano
2017-09-25 9:54 ` [PATCH v2 2/5] p0008-abbrev.sh: Test find_unique_abbrev() perf Derrick Stolee
2017-09-26 9:27 ` Junio C Hamano
2017-10-05 8:55 ` Jeff King
2017-10-05 8:57 ` Jeff King
2017-09-25 9:54 ` [PATCH v2 3/5] sha1_name: Unroll len loop in find_unique_abbrev_r Derrick Stolee
2017-09-25 9:54 ` [PATCH v2 4/5] sha1_name: Parse less while finding common prefix Derrick Stolee
2017-09-25 23:42 ` Stefan Beller
2017-10-02 14:52 ` Derrick Stolee
2017-09-25 9:54 ` [PATCH v2 5/5] sha1_name: Minimize OID comparisons during disambiguation Derrick Stolee
2017-10-02 14:56 ` [PATCH v3 0/5] Improve abbreviation disambituation Derrick Stolee
2017-10-05 9:49 ` Jeff King
2017-10-02 14:56 ` [PATCH v3 1/5] test-list-objects: List a subset of object ids Derrick Stolee
2017-10-03 4:16 ` Junio C Hamano
2017-10-02 14:56 ` [PATCH v3 2/5] p0008-abbrev.sh: Test find_unique_abbrev() perf Derrick Stolee
2017-10-02 14:56 ` [PATCH v3 3/5] sha1_name: Unroll len loop in find_unique_abbrev_r Derrick Stolee
2017-10-03 10:49 ` Junio C Hamano
2017-10-03 11:26 ` Derrick Stolee
2017-10-04 6:10 ` Junio C Hamano
2017-10-04 13:06 ` Derrick Stolee
2017-10-04 6:07 ` Junio C Hamano
2017-10-04 13:19 ` Derrick Stolee
2017-10-05 1:26 ` Junio C Hamano
2017-10-05 9:13 ` Jeff King
2017-10-05 9:50 ` Junio C Hamano
2017-10-02 14:56 ` [PATCH v3 4/5] sha1_name: Parse less while finding common prefix Derrick Stolee
2017-10-04 6:14 ` Junio C Hamano
2017-10-02 14:56 ` [PATCH v3 5/5] sha1_name: Minimize OID comparisons during disambiguation Derrick Stolee
2017-10-03 15:55 ` Stefan Beller
2017-10-03 17:05 ` Derrick Stolee
2017-10-05 9:44 ` Jeff King
2017-10-06 13:52 ` [PATCH] cleanup: fix possible overflow errors in binary search Derrick Stolee
2017-10-06 14:18 ` Jeff King
2017-10-06 14:41 ` Derrick Stolee
2017-10-08 18:29 ` [PATCH v2] " Derrick Stolee
2017-10-09 13:33 ` Jeff King
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