From: Andi Kleen <ak@suse.de>
To: Neil Horman <nhorman@tuxdriver.com>
Cc: a.zummo@towertech.it, jg@freedesktop.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] RTC: Add mmap method to rtc character driver
Date: 26 Jul 2006 17:16:53 +0200 [thread overview]
Message-ID: <p73bqrc5rbu.fsf@verdi.suse.de> (raw)
In-Reply-To: <20060725174100.GA4608@hmsreliant.homelinux.net>
Neil Horman <nhorman@tuxdriver.com> writes:
> At OLS last week, During Dave Jones Userspace Sucks presentation, Jim
> Geddys and some of the Xorg guys noted that they would be able to stop using gettimeofday
> so frequently, if they had some other way to get a millisecond resolution timer
> in userspace,
No, no, it's wrong. They should use gettimeofday and the kernel's job
is to make it fast enough that they can.
Or rather they likely shouldn't use gettimeofday, but clock_gettime()
with CLOCK_MONOTONIC instead to be independent of someone setting the
clock back.
Memory mapped counters are generally not flexible enough and there
are lots of reasons why the kernel might need to do special things
for time keeping. Don't expose them.
-Andi
next prev parent reply other threads:[~2006-07-26 15:17 UTC|newest]
Thread overview: 87+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-07-25 17:41 [PATCH] RTC: Add mmap method to rtc character driver Neil Horman
2006-07-25 17:55 ` Arjan van de Ven
2006-07-25 18:01 ` Jim Gettys
2006-07-25 18:22 ` Neil Horman
2006-07-25 18:32 ` Arjan van de Ven
2006-07-25 18:43 ` Neil Horman
2006-07-25 18:53 ` Arjan van de Ven
2006-07-25 19:03 ` Neil Horman
2006-07-25 19:06 ` Arjan van de Ven
2006-07-25 19:07 ` John W. Linville
2006-07-25 19:16 ` Arjan van de Ven
2006-07-25 19:08 ` H. Peter Anvin
2006-07-25 17:57 ` Segher Boessenkool
2006-07-25 18:28 ` Neil Horman
2006-07-25 18:56 ` Segher Boessenkool
2006-07-25 19:07 ` Neil Horman
2006-07-25 19:10 ` H. Peter Anvin
2006-07-25 19:21 ` Neil Horman
2006-07-25 19:31 ` Segher Boessenkool
2006-07-25 19:47 ` Neil Horman
2006-07-25 20:04 ` Dave Airlie
2006-07-25 20:24 ` H. Peter Anvin
2006-07-25 20:47 ` Neil Horman
2006-07-25 20:50 ` H. Peter Anvin
2006-07-25 22:25 ` Neil Horman
2006-07-25 22:33 ` H. Peter Anvin
2006-07-25 23:10 ` Neil Horman
2006-07-25 23:22 ` H. Peter Anvin
2006-07-26 0:03 ` Neil Horman
2006-07-25 23:29 ` David Lang
2006-07-26 0:18 ` Neil Horman
2006-07-25 23:29 ` Segher Boessenkool
2006-07-25 23:56 ` Neil Horman
2006-07-26 0:02 ` H. Peter Anvin
2006-07-26 0:20 ` Neil Horman
2006-07-26 0:36 ` H. Peter Anvin
2006-07-26 14:45 ` A better interface, perhaps: a timed signal flag Theodore Tso
2006-07-28 13:33 ` Steven Rostedt
2006-07-28 14:52 ` Theodore Tso
2006-07-28 15:05 ` Steven Rostedt
2006-07-28 16:41 ` Alan Cox
2006-07-28 16:44 ` Steven Rostedt
2006-07-28 20:01 ` Alan Cox
2006-07-28 20:12 ` Steven Rostedt
2006-07-28 20:36 ` Alan Cox
2006-07-28 20:31 ` Steven Rostedt
2006-07-28 17:11 ` H. Peter Anvin
2006-07-25 20:58 ` [PATCH] RTC: Add mmap method to rtc character driver Jim Gettys
2006-07-25 21:04 ` H. Peter Anvin
2006-07-25 21:14 ` Jim Gettys
2006-07-25 21:18 ` H. Peter Anvin
2006-07-25 21:39 ` Jim Gettys
2006-07-29 4:28 ` Bill Huey
2006-07-29 12:54 ` Neil Horman
2006-07-29 20:41 ` Bill Huey
2006-07-29 21:43 ` Neil Horman
2006-07-29 22:45 ` Keith Packard
2006-07-29 23:18 ` Edgar Toernig
2006-07-29 21:49 ` Edgar Toernig
2006-07-29 22:51 ` itimer again (Re: [PATCH] RTC: Add mmap method to rtc character driver) Bill Huey
2006-07-29 23:35 ` Nicholas Miell
2006-07-30 1:00 ` Bill Huey
2006-07-30 1:22 ` Nicholas Miell
2006-07-30 1:39 ` Bill Huey
2006-07-30 2:02 ` Nicholas Miell
2006-07-30 14:33 ` Theodore Tso
2006-07-30 22:20 ` Bill Huey
2006-07-31 15:40 ` Theodore Tso
2006-07-30 0:16 ` Edgar Toernig
2006-07-30 0:24 ` Bill Huey
2006-07-29 14:02 ` [PATCH] RTC: Add mmap method to rtc character driver Thomas Gleixner
2006-07-26 13:17 ` Martin J. Bligh
2006-08-02 3:54 ` john stultz
2006-08-02 4:26 ` H. Peter Anvin
2006-08-02 4:34 ` john stultz
2006-07-25 23:26 ` Segher Boessenkool
2006-07-26 0:10 ` Neil Horman
2006-07-25 20:03 ` Paul Mackerras
2006-07-25 23:27 ` Segher Boessenkool
2006-07-26 0:06 ` Neil Horman
2006-07-25 18:00 ` Jim Gettys
2006-07-25 18:17 ` Neil Horman
2006-07-26 15:16 ` Andi Kleen [this message]
2006-07-26 17:25 ` Jim Gettys
2006-07-27 23:53 ` Paul Mackerras
2006-07-28 3:29 ` Jim Gettys
2006-07-28 11:59 ` Neil Horman
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