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From: Jeff Hostetler <git@jeffhostetler.com>
To: Jeff King <peff@peff.net>
Cc: git@vger.kernel.org, gitster@pobox.com,
	Jeff Hostetler <jeffhost@microsoft.com>
Subject: Re: [PATCH v2 0/2] read-cache: call verify_hdr() in a background thread
Date: Tue, 28 Mar 2017 11:30:47 -0400	[thread overview]
Message-ID: <bf02e996-0b4b-f2ed-09b1-c99bb93c800f@jeffhostetler.com> (raw)
In-Reply-To: <20170327224505.ngp2gel3yvqcjrhw@sigill.intra.peff.net>



On 3/27/2017 6:45 PM, Jeff King wrote:
> On Mon, Mar 27, 2017 at 09:09:37PM +0000, git@jeffhostetler.com wrote:
>
>> From: Jeff Hostetler <jeffhost@microsoft.com>
>>
>> Version 2 of this patch series simplifies this to just
>> turn off the hash verification.  Independent comments
>> from Linus and Peff suggested that we could just turn
>> this off and not worry about it.  So I've updated this
>> patch to do that.  I added a global variable to allow
>> the original code path to be used.  I also added a
>> t/helper command to demonstrate the differences.
>>
>> On the Linux repo, the effect is rather trivial:
>>
>>     $ ~/work/gfw/t/helper/test-skip-verify-index -c 3
>>     0.029884 0 [cache_nr 57994]
>>     0.031035 0 [cache_nr 57994]
>>     0.024308 0 [cache_nr 57994]
>>     0.028409 0 avg
>>     0.018359 1 [cache_nr 57994]
>>     0.017025 1 [cache_nr 57994]
>>     0.011087 1 [cache_nr 57994]
>>     0.015490 1 avg
>>
>> On my Windows source tree (450MB index), I'm seeing a
>> savings of 0.6 seconds -- read_index() went from 1.2 to 0.6
>> seconds.
>
> Very satisfying. I assume that was with OpenSSL as the SHA-1
> implementation (sha1dc would have been much slower on 450MB, I think).
>
> -Peff
>

Yes, this was with the OpenSSL SHA-1 code in a GfW build.
I haven't played with the sha1dc code yet.

$ $/work/gh_gfw/t/helper/test-skip-verify-index.exe -c 5
1.276485 0 [cache_nr 3077831]
1.261164 0 [cache_nr 3077831]
1.256012 0 [cache_nr 3077831]
1.261411 0 [cache_nr 3077831]
1.266174 0 [cache_nr 3077831]
1.264249 0 avg
0.672057 1 [cache_nr 3077831]
0.666968 1 [cache_nr 3077831]
0.668725 1 [cache_nr 3077831]
0.675879 1 [cache_nr 3077831]
0.670213 1 [cache_nr 3077831]
0.670768 1 avg

Jeff

      reply	other threads:[~2017-03-28 15:31 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-27 21:09 [PATCH v2 0/2] read-cache: call verify_hdr() in a background thread git
2017-03-27 21:09 ` [PATCH v2 1/2] read-cache: skip index SHA verification git
2017-03-27 22:44   ` Jeff King
2017-03-27 23:32     ` Jonathan Nieder
2017-03-27 23:39       ` Jeff King
2017-03-28 15:27     ` Jeff Hostetler
2017-03-28 15:37       ` Jeff King
2017-03-27 21:09 ` [PATCH v2 2/2] skip_verify_index: helper test git
2017-03-27 22:45 ` [PATCH v2 0/2] read-cache: call verify_hdr() in a background thread Jeff King
2017-03-28 15:30   ` Jeff Hostetler [this message]

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