From: Peter Zijlstra <peterz@infradead.org>
To: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Andy Lutomirski <luto@amacapital.net>,
umgwanakikbuti@gmail.com, mingo@kernel.org, tglx@linutronix.de,
nicolas.pitre@linaro.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/6] sched,trace: Add a tracepoint for remote wakeups via polling
Date: Wed, 4 Jun 2014 15:54:58 +0200 [thread overview]
Message-ID: <20140604135458.GN30445@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <538F186A.2060801@linaro.org>
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On Wed, Jun 04, 2014 at 03:00:26PM +0200, Daniel Lezcano wrote:
> On 06/04/2014 02:29 AM, Andy Lutomirski wrote:
> >Remote wakeups of polling CPUs are a valuable performance
> >improvement; add a tracepoint to make it much easier to verify that
> >they're working.
> >
> >Signed-off-by: Andy Lutomirski <luto@amacapital.net>
>
> I don't think this trace makes sense. The polling state is x86 only and this
> trace is in the generic code.
Not so, there's PPC using it someplace (ISTR its doing a polling
amortization of the idle hypercall or somesuch) and there's archs that
have no other idle means that polling, as well as some for which its
optional.
There are indeed archs, like arm, that only do the WFI thing, and for
those this is indeed all a NOP.
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next prev parent reply other threads:[~2014-06-04 13:55 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-04 0:29 [PATCH 0/6] sched: Cleanup and improve polling idle loops Andy Lutomirski
2014-06-04 0:29 ` [PATCH 1/6] cpuidle: Set polling in poll_idle Andy Lutomirski
2014-06-04 0:29 ` [PATCH 2/6] sched,trace: Add a tracepoint for remote wakeups via polling Andy Lutomirski
2014-06-04 13:00 ` Daniel Lezcano
2014-06-04 13:54 ` Peter Zijlstra [this message]
2014-06-04 14:43 ` Andy Lutomirski
2014-06-04 0:29 ` [PATCH 3/6] sched,idle: Clarify where TIF_NRFLAG_POLLING is set Andy Lutomirski
2014-06-04 13:03 ` Daniel Lezcano
2014-06-04 14:58 ` Andy Lutomirski
2014-06-04 0:29 ` [PATCH 4/6] sched,idle: Clear polling before descheduling the idle thread Andy Lutomirski
2014-06-04 7:44 ` Peter Zijlstra
2014-06-04 14:57 ` Andy Lutomirski
2014-06-04 16:03 ` Peter Zijlstra
2014-06-04 7:53 ` Peter Zijlstra
2014-06-04 14:46 ` Andy Lutomirski
2014-06-04 0:29 ` [PATCH 5/6] sched,idle: Simplify wake_up_idle_cpu Andy Lutomirski
2014-06-04 0:29 ` [PATCH 6/6] sched: Optimize ttwu IPI Andy Lutomirski
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