From: Eliezer Tamir <eliezer.tamir@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>,
lenb@kernel.org, rjw@rjwysocki.net, rui.zhang@intel.com,
jacob.jun.pan@linux.intel.com,
Mike Galbraith <bitbucket@online.de>,
Ingo Molnar <mingo@kernel.org>,
hpa@zytor.com, paulmck@linux.vnet.ibm.com,
Thomas Gleixner <tglx@linutronix.de>,
John Stultz <john.stultz@linaro.org>,
Andy Lutomirski <luto@amacapital.net>,
linux-kernel@vger.kernel.org,
Eliezer Tamir <eliezer@tamir.org.il>
Subject: Re: [PATCH 00/15] cleanups and optimizations
Date: Tue, 17 Dec 2013 20:19:53 +0200 [thread overview]
Message-ID: <52B095C9.7040105@linux.intel.com> (raw)
In-Reply-To: <20131217151337.GN21999@twins.programming.kicks-ass.net>
On 17/12/2013 17:13, Peter Zijlstra wrote:
> On Tue, Dec 17, 2013 at 04:03:58PM +0200, Eliezer Tamir wrote:
>>
>> I'm not sure that subtracting the spin time is the optimal thing to do.
>>
>> The busy poll time is supposed to be limited to something less than 1ms.
>> (I'm using 50us in most of my tests)
>> This is typically orders of magnitude smaller than the poll timeout.
>> Would it make more sense to just enforce a limit on poll time?
>>
>> What do you think?
>
> I've no idea what people normally expect of select/poll wakeup
> granularity but typically we already have 50us of timer slack, although
> RT tasks go without this.
If RT tasks can't accept 50us of fuzziness, then the
path of least astonishment would be to have fully accurate
timekeeping, as you suggested. OK, so that's the plan.
Thanks,
Eliezer
next prev parent reply other threads:[~2013-12-17 18:21 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-12 14:08 [PATCH 00/15] cleanups and optimizations Peter Zijlstra
2013-12-12 14:08 ` [PATCH 01/15] x86, acpi, idle: Restructure the mwait idle routines Peter Zijlstra
2013-12-19 20:09 ` [tip:x86/idle] " tip-bot for Peter Zijlstra
2013-12-19 20:13 ` H. Peter Anvin
2013-12-19 20:16 ` Peter Zijlstra
2013-12-12 14:08 ` [PATCH 02/15] sched, preempt: Fixup missed PREEMPT_NEED_RESCHED folding Peter Zijlstra
2013-12-12 14:08 ` [PATCH 03/15] preempt, locking: Rework local_bh_{dis,en}able() Peter Zijlstra
2013-12-12 14:08 ` [PATCH 04/15] locking: Optimize lock_bh functions Peter Zijlstra
2013-12-12 14:08 ` [PATCH 05/15] sched, net: Clean up preempt_enable_no_resched() abuse Peter Zijlstra
2013-12-12 14:08 ` [PATCH 06/15] sched, net: Fixup busy_loop_us_clock() Peter Zijlstra
2013-12-12 14:08 ` [PATCH 07/15] sched, thermal: Clean up preempt_enable_no_resched() abuse Peter Zijlstra
2013-12-12 14:08 ` [PATCH 08/15] preempt: Take away preempt_enable_no_resched() from modules Peter Zijlstra
2013-12-12 14:08 ` [PATCH 09/15] x86: Use mul_u64_u32_shr() for native_sched_clock() Peter Zijlstra
2013-12-12 14:08 ` [PATCH 10/15] x86: Move some code around Peter Zijlstra
2013-12-12 14:08 ` [PATCH 11/15] x86: Rewrite cyc2ns to avoid the need to disable IRQs Peter Zijlstra
2014-06-16 17:13 ` Viresh Kumar
2014-06-17 12:15 ` Peter Zijlstra
2014-06-17 12:42 ` Viresh Kumar
2014-06-17 16:32 ` Mauro
2014-06-17 12:47 ` Mauro
2013-12-12 14:08 ` [PATCH 12/15] sched: Remove local_irq_disable() from the clocks Peter Zijlstra
2013-12-12 14:08 ` [PATCH 13/15] sched: Use a static_key for sched_clock_stable Peter Zijlstra
2014-01-21 22:28 ` Sasha Levin
2014-01-22 10:45 ` Peter Zijlstra
2014-01-22 11:59 ` Peter Zijlstra
2014-01-23 1:53 ` Dave Young
2014-01-23 16:46 ` [tip:sched/urgent] sched/clock: Fixup early initialization tip-bot for Peter Zijlstra
2014-01-22 12:00 ` [PATCH 13/15] sched: Use a static_key for sched_clock_stable Markus Trippelsdorf
2014-01-22 12:07 ` Peter Zijlstra
2014-01-22 12:16 ` Peter Zijlstra
2014-01-22 12:26 ` Markus Trippelsdorf
2014-01-22 12:30 ` Peter Zijlstra
2014-01-22 13:14 ` Markus Trippelsdorf
2014-01-22 14:26 ` Sasha Levin
2014-01-22 18:35 ` Markus Trippelsdorf
2014-01-22 18:42 ` Peter Zijlstra
2014-01-22 18:45 ` Markus Trippelsdorf
2014-01-22 19:17 ` Josh Boyer
2014-01-22 19:09 ` Markus Trippelsdorf
2014-01-22 19:12 ` Markus Trippelsdorf
2014-01-22 20:16 ` Peter Zijlstra
2014-01-22 21:08 ` Peter Zijlstra
2014-01-22 21:17 ` Markus Trippelsdorf
2014-01-23 9:48 ` Peter Zijlstra
2014-01-23 10:01 ` Markus Trippelsdorf
2014-01-23 10:04 ` Peter Zijlstra
2014-01-23 13:32 ` Josh Boyer
2014-01-23 16:46 ` [tip:sched/urgent] sched/x86/tsc: Initialize multiplier to 0 tip-bot for Peter Zijlstra
2014-01-22 23:53 ` [PATCH 13/15] sched: Use a static_key for sched_clock_stable Josh Boyer
2014-01-23 1:53 ` Dave Young
2014-01-23 2:10 ` Dave Young
2014-01-23 16:56 ` Peter Zijlstra
2014-01-24 3:15 ` Dave Young
2014-01-24 7:58 ` Ingo Molnar
2014-01-22 17:14 ` Peter Zijlstra
2014-01-22 22:31 ` Sasha Levin
2013-12-12 14:08 ` [PATCH 14/15] sched, clock: Fixup clear_sched_clock_stable() Peter Zijlstra
2013-12-12 14:08 ` [PATCH 15/15] x86: Avoid a runtime condition in native_sched_clock() Peter Zijlstra
2013-12-13 3:30 ` [PATCH 00/15] cleanups and optimizations Mike Galbraith
2013-12-13 10:49 ` Eliezer Tamir
2013-12-13 13:56 ` Peter Zijlstra
2013-12-16 17:48 ` Eliezer Tamir
2013-12-17 13:32 ` Peter Zijlstra
2013-12-17 14:03 ` Eliezer Tamir
2013-12-17 15:13 ` Peter Zijlstra
2013-12-17 18:19 ` Eliezer Tamir [this message]
2013-12-17 22:11 ` Thomas Gleixner
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