From: marc.zyngier@arm•com (Marc Zyngier)
To: linux-arm-kernel@lists•infradead.org
Subject: [RFC PATCH] ARM: sched_clock: allow sched_clock to be selected at runtime
Date: Wed, 10 Aug 2011 15:16:42 +0100 [thread overview]
Message-ID: <4E4292CA.3050704@arm.com> (raw)
In-Reply-To: <20110810114907.GA2680@pulham.picochip.com>
On 10/08/11 12:49, Jamie Iles wrote:
> Hi Marc,
>
> On Tue, Aug 09, 2011 at 06:13:35PM +0100, Marc Zyngier wrote:
>> sched_clock() is yet another blocker on the road to the single
>> image. This patch implements an idea by Russell King:
>>
>> http://www.spinics.net/lists/linux-omap/msg49561.html
>>
>> Instead of asking the platform to implement both sched_clock()
>> itself and the rollover callback, simply register a read()
>> function, and let the ARM code care about sched_clock() itself,
>> the conversion to ns and the rollover. sched_clock() uses
>> this read() function as an indirection to the platform code.
>>
>> This allow some simplifications and possibly some footprint gain
>> when multiple platforms are compiled in. Among the drawbacks,
>> the removal of the *_fixed_sched_clock optimization which could
>> negatively impact some platforms (sa1100, tegra, versatile
>> and omap).
>>
>> Tested on 11MPCore, OMAP4 and Tegra.
>
> Tested on my 1176 platform and works nicely. However, shouldn't the
> read functions still be marked notrace so they don't appear in ftrace
> output?
>
> On my (out of tree) platform, omitting notrace and having all of the
> ftrace bootup tests results in a hard lockup. Annotating the read
> function resolves this.
I'll update the patch to reflect this.
Many thanks for testing.
M.
--
Jazz is not dead. It just smells funny...
next prev parent reply other threads:[~2011-08-10 14:16 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-09 17:13 [RFC PATCH] ARM: sched_clock: allow sched_clock to be selected at runtime Marc Zyngier
2011-08-09 20:54 ` Linus Walleij
2011-08-09 21:20 ` Rob Herring
2011-08-09 21:28 ` Eric Miao
2011-08-09 21:33 ` Russell King - ARM Linux
2011-08-10 8:28 ` Marc Zyngier
2011-08-10 8:52 ` Russell King - ARM Linux
2011-08-10 8:59 ` Marc Zyngier
2011-08-10 7:13 ` Linus Walleij
2011-08-10 11:49 ` Jamie Iles
2011-08-10 14:16 ` Marc Zyngier [this message]
2011-08-11 8:25 ` Russell King - ARM Linux
2011-08-11 8:49 ` Jamie Iles
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