From: Jamie Lokier <jamie@shareable.org>
To: Peter Williams <peterw@aurema.com>
Cc: Micha Feigin <michf@post.tau.ac.il>, lkml <linux-kernel@vger.kernel.org>
Subject: Re: finding out the value of HZ from userspace
Date: Thu, 25 Mar 2004 17:40:53 +0000 [thread overview]
Message-ID: <20040325174053.GB11236@mail.shareable.org> (raw)
In-Reply-To: <405F70F6.5050605@aurema.com>
Peter Williams wrote:
> >Will this be USER_HZ or kernel HZ?
> >Someone earlier suggested it would be USER_HZ which would make it
> >pointless.
>
> It has to be whatever enables user space to correctly interpret values
> sent to user space as "ticks". That means USER_HZ and it's not useless
> as it enables USER_HZ to be different and/or change without breaking
> programs that use values expressed in "ticks".
It is, however, useless for the _other_ reasons userspace needs to
know kernel HZ, including as I mentioned userspace timer granularity.
(Btw, that usage would be better as a period rather than a frequency,
so that a "tickless" kernel can report zero).
The fundamental problem is that there are two values, and both values
have programs which can usefully use them.
How hard can it be to export both?
-- Jamie
next prev parent reply other threads:[~2004-03-25 17:43 UTC|newest]
Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <michf@post.tau.ac.il>
2004-03-11 14:17 ` Micha Feigin
2004-03-13 17:24 ` Arjan van de Ven
2004-03-13 19:34 ` John Reiser
2004-03-13 19:38 ` Arjan van de Ven
2004-03-13 22:14 ` Micha Feigin
2004-03-13 22:32 ` Arjan van de Ven
2004-03-14 1:05 ` Micha Feigin
2004-03-14 1:49 ` Andrew Morton
2004-03-14 14:37 ` Micha Feigin
2004-03-16 0:28 ` Peter Williams
2004-03-16 6:33 ` Arjan van de Ven
2004-03-16 23:38 ` Peter Williams
2004-03-20 10:22 ` Arjan van de Ven
2004-03-20 11:28 ` Stefan Smietanowski
2004-03-20 11:41 ` Arjan van de Ven
2004-03-20 23:58 ` Peter Williams
2004-03-21 1:09 ` Tim Schmielau
2004-03-21 1:30 ` Peter Williams
2004-03-21 8:00 ` Kai Henningsen
2004-03-21 10:32 ` Stefan Smietanowski
2004-03-22 22:34 ` Micha Feigin
2004-03-22 23:04 ` Peter Williams
2004-03-25 17:40 ` Jamie Lokier [this message]
2004-03-25 23:22 ` Peter Williams
2004-03-27 13:31 ` Jamie Lokier
2004-03-27 23:52 ` Peter Williams
2004-03-28 12:16 ` Jamie Lokier
2004-03-27 21:11 ` Micha Feigin
2004-03-20 23:26 ` Peter Williams
2004-03-13 21:19 ` tabris
2004-03-13 22:10 ` Micha Feigin
2004-03-13 22:41 ` Arjan van de Ven
2004-03-14 1:07 ` Micha Feigin
2004-03-14 18:26 ` John Reiser
2004-03-14 2:45 ` Horst von Brand
2004-03-14 14:39 ` Micha Feigin
2004-03-15 8:17 ` Jamie Lokier
2004-03-16 18:16 ` Mark Gross
2004-03-15 10:13 ` Richard Curnow
[not found] ` <200403161757.48786.mgross@linux.intel.com>
[not found] ` <20040317023059.GD19564@mail.shareable.org>
2004-03-17 16:48 ` Call for HRT in 2.6 kernel was " Mark Gross
2004-03-17 20:07 ` Jamie Lokier
2004-03-17 21:25 ` Mark Gross
2004-03-18 1:19 ` Karim Yaghmour
2004-03-18 11:56 ` Jamie Lokier
2004-03-18 15:23 ` Karim Yaghmour
2004-03-21 1:55 ` Erik Andersen
2004-03-23 22:35 ` Karim Yaghmour
[not found] <1zkOe-Uc-17@gated-at.bofh.it>
[not found] ` <1zl7M-1eJ-43@gated-at.bofh.it>
[not found] ` <1zn9p-3mW-5@gated-at.bofh.it>
[not found] ` <1znj5-3wM-15@gated-at.bofh.it>
[not found] ` <1AaWr-655-7@gated-at.bofh.it>
2004-03-16 2:27 ` Andi Kleen
2004-03-16 5:53 ` Peter Williams
2004-03-16 6:16 ` Andi Kleen
2004-03-16 23:15 ` Peter Williams
2004-03-16 23:56 ` Andi Kleen
2004-03-17 0:15 ` Peter Williams
2004-03-16 9:16 ` Bernd Petrovitsch
2004-03-16 23:45 ` Peter Williams
2004-03-16 16:14 Albert Cahalan
2004-03-16 17:22 ` Richard Curnow
2004-03-20 9:56 ` Arjan van de Ven
2004-03-20 14:54 ` Albert Cahalan
2004-03-20 23:58 ` Peter Williams
2004-03-31 21:40 ` Randy.Dunlap
2004-03-31 23:46 ` Albert Cahalan
2004-04-01 15:54 ` Jamie Lokier
2004-04-01 16:01 ` Arjan van de Ven
2004-04-01 16:30 ` Jamie Lokier
2004-04-01 16:50 ` Richard B. Johnson
2004-04-01 17:01 ` Jamie Lokier
2004-04-01 21:27 ` Michael Buesch
2004-04-02 0:16 ` Peter Williams
2004-04-02 0:07 ` Peter Williams
2004-04-02 0:39 ` Jamie Lokier
2004-04-02 1:44 ` Peter Williams
2004-04-02 18:28 ` Tim Bird
2004-04-02 22:05 ` Peter Williams
2004-04-01 16:12 ` Albert Cahalan
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