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Re: [patch] change futex_wait() to hrtimers

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From: Theodore Tso <tytso@...>
To: Andi Kleen <andi@...>
Cc: Thomas Gleixner <tglx@...>, Ingo Molnar <mingo@...>, Roland McGrath <roland@...>, <akpm@...>, <mm-commits@...>, <npiggin@...>, <drepper@...>, <oleg@...>, <sebastien.dugue@...>, <linux-kernel@...>
Subject: Re: [patch] change futex_wait() to hrtimers
Date: Monday, March 12, 2007 - 10:12 am

On Mon, Mar 12, 2007 at 11:58:26AM +0100, Andi Kleen wrote:

What we probably need in the long-term, and not just for high
precision wakeups, is we need a way for waiters (either in the kernel
or in userspace) to specify a desired precision in their timers.  Is
it, "wake me up in a second, exactly", or "wake me up in a second,
plus or minus 10ms"?   (or 50ms?  or 100ms?).

This becomes especially important if we want the tickless code to
really shine as far as power management is concerned.  Unfortunately,
the POSIX timer abstraction doesn't give this kind of flexibility
easily, so it's going to be a while before we see significant
userspace adoption of such a kernel feature, but I think it's
something that would be still worthwhile to add.

Regards,

						- Ted
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Messages in current thread:
[patch] change futex_wait() to hrtimers, Ingo Molnar, (Mon Mar 12, 5:10 am)
Re: [patch] change futex_wait() to hrtimers, Andi Kleen, (Mon Mar 12, 7:27 am)
Re: [patch] change futex_wait() to hrtimers, Thomas Gleixner, (Mon Mar 12, 7:00 am)
Re: [patch] change futex_wait() to hrtimers, Andi Kleen, (Mon Mar 12, 6:58 am)
Re: [patch] change futex_wait() to hrtimers, Theodore Tso, (Mon Mar 12, 10:12 am)
Re: [patch] change futex_wait() to hrtimers, Nick Piggin, (Mon Mar 12, 10:32 am)
Re: [patch] change futex_wait() to hrtimers, Ingo Molnar, (Mon Mar 12, 10:31 am)
Re: [patch] change futex_wait() to hrtimers, Andi Kleen, (Mon Mar 12, 10:22 am)
Re: [patch] change futex_wait() to hrtimers, Ingo Molnar, (Mon Mar 12, 7:04 am)
Re: [patch] change futex_wait() to hrtimers, Andi Kleen, (Mon Mar 12, 7:20 am)
Re: [patch] change futex_wait() to hrtimers, Ingo Molnar, (Mon Mar 12, 7:28 am)
Re: [patch] change futex_wait() to hrtimers, Nick Piggin, (Mon Mar 12, 5:16 am)
Re: [patch] change futex_wait() to hrtimers, Ingo Molnar, (Mon Mar 12, 7:02 am)
Re: [patch] change futex_wait() to hrtimers, Nick Piggin, (Mon Mar 12, 7:13 am)
Re: [patch] change futex_wait() to hrtimers, Ingo Molnar, (Mon Mar 12, 7:19 am)
Re: [patch] change futex_wait() to hrtimers, Nick Piggin, (Mon Mar 12, 7:29 am)
Re: [patch] change futex_wait() to hrtimers, Ingo Molnar, (Mon Mar 12, 7:38 am)
Re: [patch] change futex_wait() to hrtimers, Nick Piggin, (Mon Mar 12, 7:52 am)
Re: [patch] change futex_wait() to hrtimers, Ingo Molnar, (Mon Mar 12, 8:21 am)
Re: [patch] change futex_wait() to hrtimers, Nick Piggin, (Mon Mar 12, 8:36 am)
Re: [patch] change futex_wait() to hrtimers, Thomas Gleixner, (Mon Mar 12, 7:19 am)