[Intel-gfx] freedesktop bug id: 100548, bisected to sched/clock commit

[Martin Peres]

On 12/04/17 15:31, Peter Zijlstra wrote:
> On Wed, Apr 12, 2017 at 12:04:00PM +0000, Lofstedt, Marta wrote:
>> Hi,
>>
>> We have this "old" Lenovo Cantiga laptop(Intel Core 2 Duo L9400), hocked up to our i915 pre-merge CI system, that has started to give unstable results after commit:
>>
>> commit 7b09cc5a9debc86c903c2eff8f8a1fdef773c649
>> Author: Pavel Tatashin <pasha.tatashin at oracle.com>
>> Date:   Wed Mar 22 16:24:17 2017 -0400
>>
>>     sched/clock: Fix broken stable to unstable transfer
>>
>> The issue is describe more in detail here:
>> https://bugs.freedesktop.org/show_bug.cgi?id=100548
>
> I don't click links.
>
>> We have reverted above patch and then issue is no longer reproducible.
>> Also, note that this issue has not been reproduced on any of our other machines,
>> https://intel-gfx-ci.01.org/CI/
>>
>> So, why is this only affecting the Core 2 Duo?
>
> Core2 doesn't have a usable TSC and would revert to the slow path. I'll
> have another look at that patch.
>

So, by default, it is using the hpet clock source. FYI, I tried the only 
other available clock source (acpi_pm) and got the same result.