From: Santosh Shilimkar <santosh.shilimkar@ti.com>
To: Will Deacon <will.deacon@arm.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"arm@kernel.org" <arm@kernel.org>,
Stephen Boyd <sboyd@codeaurora.org>,
John Stultz <john.stultz@linaro.org>,
Russell King <linux@arm.linux.org.uk>,
"rob.herring@calxeda.com" <rob.herring@calxeda.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH] sched_clock: fix postinit no sched_clock function check
Date: Wed, 2 Oct 2013 13:14:44 -0400 [thread overview]
Message-ID: <524C5484.5000601@ti.com> (raw)
In-Reply-To: <20131002170917.GB30298@mudshark.cambridge.arm.com>
On Wednesday 02 October 2013 01:09 PM, Will Deacon wrote:
> On Wed, Oct 02, 2013 at 05:55:28PM +0100, Santosh Shilimkar wrote:
>> The sched_clock code uses 2 levels of function pointers, sched_clock_func()
>> and read_sched_clock() but the no sched_clock check in postinit() just
>> checks read_sched_clock().
>>
>> This leads to kernel falling back to jiffy based sched clock even in
>> presence of sched_clock_func() which is not desirable.
>>
>> Fix the postinit() check to avoid the issue. Probably the issue is hidden
>> so far on most of the arm SOCs because of already existing sched_clock
>> registrations apart from arch_timer sched_clock. One can reproduce the
>> issue by just have arch_timer as sched_clock
>
> Isn't this just an issue with the arch timer driver not calling
> setup_sched_clock? Instead, we munge around with sched_clock_func directly,
> which doesn't appear to be the way anybody else deals with this.
>
I thought about that option as well but was not sure since even in that case
the check is not complete. We just ensure that function is popullated.
> I'm not sure of the history though, so perhaps there's a reason for this...
>
Am curious as well.
Regards,
Santosh
next prev parent reply other threads:[~2013-10-02 17:15 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-02 16:55 [PATCH] sched_clock: fix postinit no sched_clock function check Santosh Shilimkar
2013-10-02 17:09 ` Will Deacon
2013-10-02 17:14 ` Santosh Shilimkar [this message]
2013-10-02 17:22 ` Stephen Boyd
2013-10-02 17:27 ` Santosh Shilimkar
2013-10-02 17:42 ` Stephen Boyd
2013-10-02 17:48 ` Will Deacon
2013-10-02 18:07 ` Santosh Shilimkar
2013-10-09 23:59 ` John Stultz
2013-10-10 0:15 ` Santosh Shilimkar
2013-10-02 18:14 ` Rob Herring
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