From: Peter Zijlstra <peterz@infradead.org>
To: john stultz <johnstul@us.ibm.com>
Cc: Linus Walleij <linus.ml.walleij@gmail.com>,
Paul Mundt <lethal@linux-sh.org>, Ingo Molnar <mingo@elte.hu>,
Andrew Victor <linux@maxim.org.za>,
Haavard Skinnemoen <hskinnemoen@atmel.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-sh@vger.kernel.org,
linux-arm-kernel@lists.arm.linux.org.uk,
John Stultz <johnstul@linux.vnet.ibm.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH] sched: Support current clocksource handling in
Date: Wed, 27 May 2009 06:58:46 +0000 [thread overview]
Message-ID: <1243407526.23657.37.camel@twins> (raw)
In-Reply-To: <1243378835.3275.30.camel@localhost>
On Tue, 2009-05-26 at 16:00 -0700, john stultz wrote:
> Sure, I guess what I'm trying to pull out here is that should we try to
> create some OK_FOR_SCHED_CLOCK flag for clocksources, and then we try to
> make this generic so other arches can add that flag and be done, what is
> the guidance we want to give to arch maintainers for setting that flag?
>
> 1) Has to be very very fast. Can we put a number on this? 50ns to read?
I'd express it in cpu cycles, but not sure, the very fastest the arch
has :-) Just tell people this is in their scheduling hot-path and they
might understand.
> 2) How long does it have to be monotonic for?
Forever? (per cpu)
> Is it ok if it wraps every few seconds?
No, if it wraps it needs to wrap on u64.
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: john stultz <johnstul@us.ibm.com>
Cc: Linus Walleij <linus.ml.walleij@gmail.com>,
Paul Mundt <lethal@linux-sh.org>, Ingo Molnar <mingo@elte.hu>,
Andrew Victor <linux@maxim.org.za>,
Haavard Skinnemoen <hskinnemoen@atmel.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-sh@vger.kernel.org,
linux-arm-kernel@lists.arm.linux.org.uk,
John Stultz <johnstul@linux.vnet.ibm.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH] sched: Support current clocksource handling in fallback sched_clock().
Date: Wed, 27 May 2009 08:58:46 +0200 [thread overview]
Message-ID: <1243407526.23657.37.camel@twins> (raw)
In-Reply-To: <1243378835.3275.30.camel@localhost>
On Tue, 2009-05-26 at 16:00 -0700, john stultz wrote:
> Sure, I guess what I'm trying to pull out here is that should we try to
> create some OK_FOR_SCHED_CLOCK flag for clocksources, and then we try to
> make this generic so other arches can add that flag and be done, what is
> the guidance we want to give to arch maintainers for setting that flag?
>
> 1) Has to be very very fast. Can we put a number on this? 50ns to read?
I'd express it in cpu cycles, but not sure, the very fastest the arch
has :-) Just tell people this is in their scheduling hot-path and they
might understand.
> 2) How long does it have to be monotonic for?
Forever? (per cpu)
> Is it ok if it wraps every few seconds?
No, if it wraps it needs to wrap on u64.
next prev parent reply other threads:[~2009-05-27 6:58 UTC|newest]
Thread overview: 114+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-26 6:15 [PATCH] sched: Support current clocksource handling in fallback sched_clock() Paul Mundt
2009-05-26 6:15 ` Paul Mundt
2009-05-26 14:31 ` [PATCH] sched: Support current clocksource handling in fallback Linus Walleij
2009-05-26 14:31 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Linus Walleij
2009-05-26 14:38 ` [PATCH] sched: Support current clocksource handling in Peter Zijlstra
2009-05-26 14:38 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Peter Zijlstra
2009-05-26 20:17 ` [PATCH] sched: Support current clocksource handling in fallback Thomas Gleixner
2009-05-26 20:17 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Thomas Gleixner
2009-05-26 23:08 ` Paul Mundt
2009-05-26 23:08 ` Paul Mundt
2009-05-26 23:13 ` Paul Mundt
2009-05-26 23:13 ` Paul Mundt
2009-05-26 23:25 ` [PATCH] sched: Support current clocksource handling in john stultz
2009-05-26 23:25 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() john stultz
2009-05-26 23:44 ` Paul Mundt
2009-05-26 23:44 ` Paul Mundt
2009-05-27 0:18 ` [PATCH] sched: Support current clocksource handling in fallback Thomas Gleixner
2009-05-27 0:18 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Thomas Gleixner
2009-05-27 0:22 ` [PATCH] sched: Support current clocksource handling in john stultz
2009-05-27 0:22 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() john stultz
2009-05-27 0:26 ` Paul Mundt
2009-05-27 0:26 ` Paul Mundt
2009-05-27 1:09 ` [PATCH] sched: Support current clocksource handling in john stultz
2009-05-27 1:09 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() john stultz
2009-05-27 0:27 ` [PATCH] sched: Support current clocksource handling in fallback Thomas Gleixner
2009-05-27 0:27 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Thomas Gleixner
2009-05-26 23:49 ` [PATCH] sched: Support current clocksource handling in fallback Thomas Gleixner
2009-05-26 23:49 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Thomas Gleixner
2009-05-27 0:15 ` Paul Mundt
2009-05-27 0:15 ` Paul Mundt
2009-05-27 16:25 ` [PATCH] sched: Support current clocksource handling in Daniel Walker
2009-05-27 16:25 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Daniel Walker
2009-05-28 8:44 ` Paul Mundt
2009-05-28 8:44 ` Paul Mundt
2009-05-28 9:19 ` Paul Mundt
2009-05-28 9:19 ` Paul Mundt
2009-05-28 9:34 ` [PATCH] sched: Support current clocksource handling in Peter Zijlstra
2009-05-28 9:34 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Peter Zijlstra
2009-05-28 11:09 ` Paul Mundt
2009-05-28 11:09 ` Paul Mundt
2009-05-28 12:22 ` [PATCH] sched: Support current clocksource handling in fallback Thomas Gleixner
2009-05-28 12:22 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Thomas Gleixner
2009-05-28 12:40 ` [PATCH] sched: Support current clocksource handling in Peter Zijlstra
2009-05-28 12:40 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Peter Zijlstra
2009-05-28 12:42 ` Paul Mundt
2009-05-28 12:42 ` Paul Mundt
2009-05-28 12:53 ` [PATCH] sched: Support current clocksource handling in fallback Thomas Gleixner
2009-05-28 12:53 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Thomas Gleixner
2009-05-28 12:59 ` [PATCH] sched: Support current clocksource handling in Peter Zijlstra
2009-05-28 12:59 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Peter Zijlstra
2009-05-28 13:20 ` Paul Mundt
2009-05-28 13:20 ` Paul Mundt
2009-05-28 16:13 ` [PATCH] sched: Support current clocksource handling in Daniel Walker
2009-05-28 16:13 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Daniel Walker
2009-05-28 16:32 ` [PATCH] sched: Support current clocksource handling in Peter Zijlstra
2009-05-28 16:32 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Peter Zijlstra
2009-05-28 16:40 ` Paul Mundt
2009-05-28 16:40 ` Paul Mundt
2009-05-28 16:52 ` [PATCH] sched: Support current clocksource handling in Daniel Walker
2009-05-28 16:52 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Daniel Walker
2009-05-28 16:58 ` Paul Mundt
2009-05-28 16:58 ` Paul Mundt
2009-05-28 17:38 ` [PATCH] sched: Support current clocksource handling in Daniel Walker
2009-05-28 17:38 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Daniel Walker
2009-05-28 17:46 ` [PATCH] sched: Support current clocksource handling in fallback Thomas Gleixner
2009-05-28 17:46 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Thomas Gleixner
2009-05-28 17:53 ` Paul Mundt
2009-05-28 17:53 ` Paul Mundt
2009-05-28 18:10 ` [PATCH] sched: Support current clocksource handling in Daniel Walker
2009-05-28 18:10 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Daniel Walker
2009-05-28 18:27 ` Paul Mundt
2009-05-28 18:27 ` Paul Mundt
2009-05-28 19:04 ` [PATCH] sched: Support current clocksource handling in Daniel Walker
2009-05-28 19:04 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Daniel Walker
2009-05-28 19:34 ` Paul Mundt
2009-05-28 19:34 ` Paul Mundt
2009-05-28 19:41 ` [PATCH] sched: Support current clocksource handling in Daniel Walker
2009-05-28 19:41 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Daniel Walker
2009-05-28 23:37 ` Paul Mundt
2009-05-28 23:37 ` Paul Mundt
2009-05-28 18:44 ` [PATCH] sched: Support current clocksource handling in fallback Thomas Gleixner
2009-05-28 18:44 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Thomas Gleixner
2009-05-28 17:00 ` [PATCH] sched: Support current clocksource handling in fallback Thomas Gleixner
2009-05-28 17:00 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Thomas Gleixner
2009-05-28 17:07 ` [PATCH] sched: Support current clocksource handling in John Stultz
2009-05-28 17:07 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() John Stultz
2009-05-26 20:23 ` [PATCH] sched: Support current clocksource handling in john stultz
2009-05-26 20:23 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() john stultz
2009-05-26 20:30 ` [PATCH] sched: Support current clocksource handling in Peter Zijlstra
2009-05-26 20:30 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Peter Zijlstra
2009-05-26 20:40 ` [PATCH] sched: Support current clocksource handling in john stultz
2009-05-26 20:40 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() john stultz
2009-05-26 20:55 ` [PATCH] sched: Support current clocksource handling in Peter Zijlstra
2009-05-26 20:55 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Peter Zijlstra
2009-05-26 23:00 ` [PATCH] sched: Support current clocksource handling in john stultz
2009-05-26 23:00 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() john stultz
2009-05-26 23:24 ` [PATCH] sched: Support current clocksource handling in fallback Mangalampalli, JayantX
2009-05-26 23:24 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Mangalampalli, JayantX
2009-05-27 0:04 ` [PATCH] sched: Support current clocksource handling in fallback Thomas Gleixner
2009-05-27 0:04 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Thomas Gleixner
2009-05-26 23:39 ` [PATCH] sched: Support current clocksource handling in fallback Thomas Gleixner
2009-05-26 23:39 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Thomas Gleixner
2009-05-27 6:58 ` Peter Zijlstra [this message]
2009-05-27 6:58 ` Peter Zijlstra
2009-05-26 20:39 ` [PATCH] sched: Support current clocksource handling in fallback Thomas Gleixner
2009-05-26 20:39 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Thomas Gleixner
2009-05-26 14:43 ` Paul Mundt
2009-05-26 14:43 ` Paul Mundt
2009-05-26 14:50 ` [PATCH] sched: Support current clocksource handling in Peter Zijlstra
2009-05-26 14:50 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Peter Zijlstra
2009-05-26 14:53 ` Paul Mundt
2009-05-26 14:53 ` Paul Mundt
2009-05-26 15:02 ` [PATCH] sched: Support current clocksource handling in fallback Matthieu CASTET
2009-05-26 15:02 ` [PATCH] sched: Support current clocksource handling in fallback sched_clock() Matthieu CASTET
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