git.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Junio C Hamano <gitster@pobox.com>
To: Taylor Blau <me@ttaylorr.com>
Cc: "Christian Göttsche" <cgzones@googlemail.com>, git@vger.kernel.org
Subject: Re: [PATCH] setup: avoid unconditional open with write flags
Date: Tue, 06 Dec 2022 09:10:51 +0900	[thread overview]
Message-ID: <xmqq7cz5pf1w.fsf@gitster.g> (raw)
In-Reply-To: <Y453yiYAifv/oV5n@nand.local> (Taylor Blau's message of "Mon, 5 Dec 2022 17:59:28 -0500")

Taylor Blau <me@ttaylorr.com> writes:

> So it appears that the old version is ever-so-slightly faster than the
> new one. But it's so noisy, and the regression is so small that it's
> hard to notice it at all.
>
> So I wouldn't strongly oppose the patch based on those numbers, but in
> principle it seems flawed.

Thanks for writing and reviewing.

As long as we were touching the function, I suspect that
the logic should become more like

    if (fd #0 is not open)
	open /dev/null read-only and give it to fd #0
    if (fd #1 is not open)
	open /dev/null write-only and give it to fd #1
    if (fd #2 is not open)
	open /dev/null write-only and give it to fd #2

with opening of /dev/null optimized not to happen when not needed.

  reply	other threads:[~2022-12-06  0:10 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-12-05 19:00 [PATCH] setup: avoid unconditional open with write flags Christian Göttsche
2022-12-05 22:13 ` brian m. carlson
2022-12-06  1:38   ` Jeff King
2022-12-06 16:15     ` Christian Göttsche
2022-12-05 22:59 ` Taylor Blau
2022-12-06  0:10   ` Junio C Hamano [this message]
2022-12-06  0:31     ` Taylor Blau
2022-12-06  0:40       ` Junio C Hamano
2022-12-06 19:47 ` René Scharfe
2022-12-06 23:39   ` Junio C Hamano

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=xmqq7cz5pf1w.fsf@gitster.g \
    --to=gitster@pobox.com \
    --cc=cgzones@googlemail.com \
    --cc=git@vger.kernel.org \
    --cc=me@ttaylorr.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).