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From: Junio C Hamano <gitster@pobox.com>
To: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Cc: Calvin Wan <calvinwan@google.com>,
	git@vger.kernel.org, emilyshaffer@google.com
Subject: Re: [PATCH 4/4] diff-lib: parallelize run_diff_files for submodules
Date: Sat, 24 Sep 2022 13:17:02 -0700	[thread overview]
Message-ID: <xmqqsfkgr0ht.fsf@gitster.g> (raw)
In-Reply-To: <220923.86o7v64ik0.gmgdl@evledraar.gmail.com> (=?utf-8?B?IsOG?= =?utf-8?B?dmFyIEFybmZqw7Zyw7A=?= Bjarmason"'s message of "Fri, 23 Sep 2022 10:06:56 +0200")

Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes:

> On Thu, Sep 22 2022, Calvin Wan wrote:
>
>> +status.parallelSubmodules::
>> +	When linkgit:git-status[1] is run in a superproject with
>> +	submodules, a status subprocess is spawned for every submodule.
>> +	This option specifies the number of submodule status subprocesses
>> +	to run in parallel. If unset, it defaults to 1.
>
> Why do we default to 1, instead of e.g. grep.threads defaulting to the
> "cores available"?

I would imagine we would want to be able to say:

 - I do not trust the parallel mode yet, just use the single process
   method that we have always been using.

 - I do not know how many cores I have, just use a reasonable
   default parallelism.

 - I want to use N processes because I know better than auto-scaling
   based on num_cpus.

And the value of 1 would be a reasonable way to express the first
one.



  reply	other threads:[~2022-09-24 20:17 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-22 23:29 [PATCH 0/4] submodule: parallelize status Calvin Wan
2022-09-22 23:29 ` [PATCH 1/4] run-command: add pipe_output to run_processes_parallel Calvin Wan
2022-09-23  7:52   ` Ævar Arnfjörð Bjarmason
2022-09-26 16:59     ` Calvin Wan
2022-09-27 10:52       ` Ævar Arnfjörð Bjarmason
2022-09-23 18:58   ` Junio C Hamano
2022-09-26 17:31     ` Calvin Wan
2022-09-27  4:45       ` Junio C Hamano
2022-09-27 18:10         ` Calvin Wan
2022-09-27 21:40           ` Junio C Hamano
2022-09-27  9:05       ` Ævar Arnfjörð Bjarmason
2022-09-27 17:55         ` Calvin Wan
2022-09-27 19:34           ` Ævar Arnfjörð Bjarmason
2022-09-27 20:45             ` Calvin Wan
2022-09-28  5:40               ` Ævar Arnfjörð Bjarmason
2022-09-29 20:52                 ` Calvin Wan
2022-09-22 23:29 ` [PATCH 2/4] submodule: move status parsing into function Calvin Wan
2022-09-22 23:29 ` [PATCH 3/4] diff-lib: refactor functions Calvin Wan
2022-09-23 20:36   ` Junio C Hamano
2022-09-26 17:35     ` Calvin Wan
2022-09-22 23:29 ` [PATCH 4/4] diff-lib: parallelize run_diff_files for submodules Calvin Wan
2022-09-23  8:06   ` Ævar Arnfjörð Bjarmason
2022-09-24 20:17     ` Junio C Hamano [this message]
2022-09-26 17:50     ` Calvin Wan
2022-09-23 21:44   ` Junio C Hamano
2022-09-26 19:12     ` Calvin Wan
2022-09-25 13:59   ` Phillip Wood
2022-09-26 17:11     ` Junio C Hamano
2022-09-26 19:22     ` Calvin Wan
2022-09-27 18:40   ` Emily Shaffer
2022-09-23 22:56 ` [PATCH 0/4] submodule: parallelize status Junio C Hamano
2022-09-26 16:33   ` Calvin Wan

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