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SubjectRe: [PATCH] sched_clock: fix postinit no sched_clock function check
On Wednesday 02 October 2013 01:48 PM, Will Deacon wrote:
> On Wed, Oct 02, 2013 at 06:42:40PM +0100, Stephen Boyd wrote:
>> On 10/02/13 10:27, Santosh Shilimkar wrote:
>>> Really... I have not created patch out of fun.
>>> Its broken on my keystone machine at least where the sched_clock is
>>> falling back on jiffy based sched_clock even in presence of arch_timer
>>> sched_clock.
>>
>> How is that possible? sched_clock_func is only assigned by
>> arch/arm/kernel/arch_timer.c when the architected timer is detected and
>> sched_clock() in kernel/time/sched_clock.c calls that function pointer
>> unconditionally. The only way I see this happening is if the architected
>> timer rate is zero.
> ^^^^^^^^^^^^^^^^^^
>
> *cough* CNTFRQ *cough*
>
:) CNTFRQ as such is fine. I think the below print mis-lead me mostly.

sched_clock: ARM arch timer >56 bits at 6144kHz, resolution 162ns
sched_clock: 32 bits at 100 Hz, resolution 10000000ns, wraps every 4294967286ms

So yes, now the subject patch actually just avoids the jiffy sched_clock()
registration and nothing else. Even without the patch arch_timer sched_clock
will be in use.

Regards,
Santosh


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