From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Dave Jones <davej@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
Anton Vorontsov <anton.vorontsov@linaro.org>,
Ingo Molnar <mingo@elte.hu>,
Russell King <linux@arm.linux.org.uk>,
Oleg Nesterov <oleg@redhat.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Nicolas Pitre <nico@fluxnic.net>, Mike Chan <mike@android.com>,
Todd Poynor <toddpoynor@google.com>,
cpufreq@vger.kernel.org, kernel-team@android.com,
linaro-kernel@lists.linaro.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org,
Arjan Van De Ven <arjan@infradead.org>
Subject: Re: [PATCH RFC 0/4] Scheduler idle notifiers and users
Date: Thu, 09 Feb 2012 08:33:54 +1100 [thread overview]
Message-ID: <1328736834.2903.33.camel@pasglop> (raw)
In-Reply-To: <20120208202314.GA28290@redhat.com>
On Wed, 2012-02-08 at 15:23 -0500, Dave Jones wrote:
> I think the biggest mistake we ever made with cpufreq was making it
> so configurable. If we redesign it, just say no to plugin governors,
> and
> yes to a lot fewer sysfs knobs.
>
> So, provide mechanism to kill off all the governors, and there's a
> migration path from what we have now to something that just works
> in a lot more cases, while remaining configurable enough for the
> corner-cases.
On the other hand, the need for schedulable contxts may not necessarily
go away.
If you look beyond x86, there's several issues that get into the
picture. i2c clock chips & power control chips are slow (the i2c bus
itself is). You don't want to spin for hundreds of microsecs while you
do those transactions.
I have seen many cases where the clock control can be done quite
quickly, but on the other hand, the voltage control takes dozens of ms
to reach the target value & stabilize.
That could be done asynchronously .. as long as the scheduler doesn't
constantly hammer it with change requests.
Cheers,
Ben.
next prev parent reply other threads:[~2012-02-08 21:34 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-08 1:39 [PATCH RFC 0/4] Scheduler idle notifiers and users Anton Vorontsov
2012-02-08 1:41 ` [PATCH 1/4] sched: Introduce idle notifiers API Anton Vorontsov
2012-02-08 1:43 ` [PATCH 2/4] sched: Wire up idle notifiers Anton Vorontsov
2012-02-08 1:44 ` [PATCH 3/4] cpufreq: New 'interactive' governor Anton Vorontsov
2012-02-08 23:00 ` Vincent Guittot
2012-02-09 0:32 ` Anton Vorontsov
2012-02-08 1:44 ` [PATCH 4/4] ARM: Move leds idle start/stop calls to sched idle notifiers Anton Vorontsov
2012-02-08 3:05 ` [PATCH RFC 0/4] Scheduler idle notifiers and users Peter Zijlstra
2012-02-08 20:23 ` Dave Jones
2012-02-08 21:33 ` Benjamin Herrenschmidt [this message]
2012-02-09 7:51 ` Ingo Molnar
2012-02-11 3:15 ` Saravana Kannan
2012-02-11 14:39 ` Mark Brown
2012-02-11 14:53 ` Peter Zijlstra
2012-02-11 15:33 ` Mark Brown
2012-02-15 13:38 ` Peter Zijlstra
2012-02-15 16:04 ` Mark Brown
2012-02-12 21:33 ` Benjamin Herrenschmidt
2012-02-11 14:45 ` Ingo Molnar
2012-02-14 23:20 ` Saravana Kannan
2012-02-15 13:38 ` Peter Zijlstra
2012-02-15 14:02 ` Russell King - ARM Linux
2012-02-15 15:01 ` Peter Zijlstra
2012-02-15 16:00 ` Russell King - ARM Linux
2012-02-15 16:09 ` Peter Zijlstra
2012-02-16 3:31 ` Benjamin Herrenschmidt
2012-02-16 10:14 ` Peter Zijlstra
2012-02-17 9:00 ` Dominik Brodowski
2012-02-20 11:03 ` Peter Zijlstra
2012-02-21 12:38 ` Pantelis Antoniou
2012-02-21 12:56 ` Peter Zijlstra
2012-02-21 13:31 ` Pantelis Antoniou
2012-02-21 14:52 ` Amit Kucheria
2012-02-21 17:06 ` Pantelis Antoniou
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