From: Paul Eggert <eggert@cs.ucla.edu>
To: Dmitry Antipov <dmantipov@yandex.ru>
Cc: Emacs development discussions <emacs-devel@gnu.org>
Subject: Re: m4/clock_time.m4 from r117596
Date: Thu, 31 Jul 2014 22:54:19 -0700 [thread overview]
Message-ID: <53DB2B8B.1060706@cs.ucla.edu> (raw)
In-Reply-To: <53DB28EA.8050301@yandex.ru>
Dmitry Antipov wrote:
> Are you sure about that? On my (Fedora 20) system, 'man timer_settime' and
> 'man timerfd_settime' says nothing about resolution and rounding.
It's a POSIX requirement for timer_settime, and I expect timerfd_settime
to be similar. I'd be surprised if the Linux kernel did it any differently.
A bit of reflection should make it clear why this is so (and why
clock_settime is different): an application must always allow for the
act of computation to advance the clock a little bit, so if the system
rounds timers up and clocks down it won't hurt apps any more than
they're hurt already simply by running.
Here's the POSIX requirement:
"Time values that are between two consecutive non-negative integer
multiples of the resolution of the specified timer shall be rounded up
to the larger multiple of the resolution."
http://pubs.opengroup.org/onlinepubs/9699919799/functions/timer_settime.html
prev parent reply other threads:[~2014-08-01 5:54 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-28 6:31 m4/clock_time.m4 from r117596 Dmitry Antipov
2014-07-31 20:19 ` Paul Eggert
2014-08-01 5:43 ` Dmitry Antipov
2014-08-01 5:54 ` Paul Eggert [this message]
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