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From: Jeff Hostetler <git@jeffhostetler.com>
To: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
	"Matheus Tavares" <matheus.bernardino@usp.br>
Cc: git@vger.kernel.org, gerardu@amazon.com,
	Derrick Stolee <stolee@gmail.com>
Subject: Re: RFC: auto-enabling parallel-checkout on NFS
Date: Thu, 19 Nov 2020 09:11:14 -0500
Message-ID: <e0ddf00d-785b-9220-0082-8be54fb7a7c6@jeffhostetler.com> (raw)
In-Reply-To: <87y2ixpvos.fsf@evledraar.gmail.com>



On 11/19/20 4:01 AM, Ævar Arnfjörð Bjarmason wrote:
> 
>> The major downside is that detecting the file system type is quite
>> platform-dependent, so there is no simple and portable solution. (Also,
>> I'm not sure if the optimal number of workers would be the same on
>> different OSes). But we decided to give it a try, so this is a
>> rough prototype that would work for Linux:
>> https://github.com/matheustavares/git/commit/2e2c787e2a1742fed8c35dba185b7cd208603de9
> 
> I'm not intrinsically opposed to hardcoding some "nr_threads = is_nfs()
> ? x : y" as a stopgap.
> 
> I do think we should be thinking about a sustainable way of doing this
> sort of thing, this method of testing once and hardcoding something
> isn't a good approach.
> 
> It doesn't anticipate all sorts of different setups, e.g. in this case
> NFS is not a FS, but a protocol, there's probably going to be some
> implementations where parallel is much worse due to a quirk of the
> implementation.
> 
> I think integrating an optimization run with the relatively new
> git-maintenance is a better way forward.
> 
> You'd configure e.g.:
> 
>      maintenance.performanceTests.enabled=true
>      maintenance.performanceTests.writeConfig=true
> 
> Which would run e.g.:
> 
>      git config --type bool core.untrackedCache $(git update-index --test-untracked-cache && echo true || echo false)
>      git config checkout.workers $(git maintenance--helper auto-discover-config checkout.workers)
> 
> Such an implementation can be really basic at first, or even just punt
> on the test and use your current "is it NFS?" check.
> 
> But I think we should be moving to some helper that does the actual test
> locally when asked/configured by the user, so we're not making a bunch
> of guesses in advance about the size/shape of the repository, OS/nfs/fs
> etc.
> 

I kinda like this idea.  It would give us a chance to let maintenance
periodically probe the repo/system and improve some of these tuning
knobs.

Jeff

  reply	other threads:[~2020-11-19 14:14 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-15 19:43 Matheus Tavares
2020-11-16 15:19 ` Jeff Hostetler
2020-11-19  4:01   ` Matheus Tavares
2020-11-19 14:04     ` Jeff Hostetler
2020-11-20 12:10       ` Ævar Arnfjörð Bjarmason
2020-11-23 23:18       ` Geert Jansen
2020-11-19  9:01 ` Ævar Arnfjörð Bjarmason
2020-11-19 14:11   ` Jeff Hostetler [this message]
2020-11-23 23:37   ` Geert Jansen
2020-11-24 12:58     ` Ævar Arnfjörð Bjarmason

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