From: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
To: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: mtk.manpages@gmail.com, linux-man@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org
Subject: Re: clock_gettime.2: _COARSE clocks are not always faster...
Date: Mon, 18 Apr 2016 16:12:50 +0100 [thread overview]
Message-ID: <5714F972.6080603@gmail.com> (raw)
In-Reply-To: <87k2k67ml4.fsf@rasmusvillemoes.dk>
Hello Rasmus,
On 04/09/2016 05:50 PM, Rasmus Villemoes wrote:
> Hi Michael
>
> The other day, I was curious how the vdso was implemented on ppc, and I
> noted that neither ppc32 or ppc64 handle the _COARSE versions of
> CLOCK_{REALTIME,MONOTONIC} in the vdso, so they fall back to an actual
> syscall. And sure enough, measuring CLOCK_MONOTONIC
> vs. CLOCK_MONOTONIC_COARSE shows that the latter has three times as much
> overhead as the former.
>
> Whether it's worth adding a note to the man page is up to you.
I think it's useful to do so. For both *COARSE flags, I added:
[[
Requires per-architecture support, and probably also architecture support
for this flag in the vdso(7).
]]
Thanks!
Michael
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
next prev parent reply other threads:[~2016-04-18 15:12 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-09 16:50 clock_gettime.2: _COARSE clocks are not always faster Rasmus Villemoes
2016-04-18 15:12 ` Michael Kerrisk (man-pages) [this message]
2016-04-18 15:23 ` Michael Kerrisk (man-pages)
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=5714F972.6080603@gmail.com \
--to=mtk.manpages@gmail.com \
--cc=linux-man@vger.kernel.org \
--cc=linux@rasmusvillemoes.dk \
--cc=linuxppc-dev@lists.ozlabs.org \
/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).