[Intel-gfx] [PATCH i-g-t v5 10/11] tests/perf: prevent power management to kick in when necessary

[Matthew Auld]

On 08/31, Lionel Landwerlin wrote:
> Some of our tests measure that the OA unit produces reports at
> expected time intervals (as configured through the PERF_OPEN
> ioctl). It turns out the power management plays a role in the decision
> of the OA unit to write reports to memory. Under normal circumstances
> we don't really mind if the unit misses one report here or there, but
> for our tests it makes pretty difficult to verify whether we've made a
> mistake in the configuration.
> 
> To work around this, let's prevent power management to kick in by
> holding /dev/cpu_dma_latency opened for the following tests :
> 
>   - blocking
>   - polling
>   - buffer-fill
>   - oa-exponents
+    - enable-disable

> 
> Many thanks to Chris Wilson for suggesting this!
> 
> Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>

Seems to cure the oa-exponents test for me, so:
Reviewed-by: Matthew Auld <matthew.auld at intel.com>