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Date:   Wed, 12 May 2021 18:05:17 +0000
From:   Eric Wong <e@80x24.org>
To:     =?utf-8?B?w4Z2YXIgQXJuZmrDtnLDsA==?= Bjarmason <avarab@gmail.com>
Cc:     git@vger.kernel.org, Junio C Hamano <gitster@pobox.com>,
        Gregory Anders <greg@gpanders.com>,
        =?utf-8?B?xJBvw6BuIFRy4bqnbiBDw7RuZw==?= Danh 
        <congdanhqx@gmail.com>, Jeff King <peff@peff.net>
Subject: Re: [PATCH 8/9] perl: lazily load some common Git.pm setup code
Message-ID: <20210512180517.GA11354@dcvr>
References: <cover-0.9-0000000000-20210512T132955Z-avarab@gmail.com>
 <patch-8.9-2312346f71-20210512T132955Z-avarab@gmail.com>
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Ævar Arnfjörð Bjarmason <avarab@gmail.com> wrote:
> @@ -408,10 +404,12 @@ sub command_bidi_pipe {
>  	my $cwd_save = undef;
>  	if ($self) {
>  		shift;
> -		$cwd_save = cwd();
> +		require Cwd;
> +		$cwd_save = Cwd::cwd();
>  		_setup_git_cmd_env($self);

(This also applies to 7/9)

Cwd::cwd() execs /bin/pwd (at least on Perl 5.28.1 in Debian 10x).
There should be a benefit from using Cwd::getcwd() here, instead.

	strace -f -e execve perl -MCwd -E 'Cwd::cwd()

...confirms the execve is happening.

getcwd() takes 25ms vs 27ms of cwd() for me using the
"schedutil" CPU governor under Linux:

	time perl -MCwd -E 'Cwd::getcwd()'
	time perl -MCwd -E 'Cwd::cwd()'