Re: [PREEMPT_RT PATCH 2/3] i915: convert all irq_locks spinlocks to raw spinlocks

[Sebastian Andrzej Siewior]

On 2019-09-03 10:03:35 [+0200], To Clark Williams wrote:
> anything in a brief test. What I saw however is that switching to
> fullscreen while playing a video gives me ~0.5 to ~2ms latency. This is
> has nothing to do with this change, I have to dig deeperâ It might be
> one of the preempt_disable() section I just noticed.
> I would prefer to keep the lock non-raw unless there is actual need for
> it.

That latency spike is caused by the iommu, qi_submit_sync() to be exact.
Without the iomm I don't see much difference between the two patchesâ
 
Sebastian