[Intel-gfx] [PATCH 01/11] drm/i915/guc: Use system workqueue for log capture

[Chris Wilson]

Quoting Daniele Ceraolo Spurio (2019-07-13 17:44:32)
> 
> 
> On 7/13/2019 3:00 AM, Chris Wilson wrote:
> > We only employ a single task for log capture, and created a workqueue
> > for the purpose of ensuring we had a high priority queue for low
> > latency. We can simply use the system_highpri_wq and avoid the
> > complication with creating our own admist the maze of mutexes.
> > (Currently we create the wq early before we even know we need it in
> > order to avoid trying to create it on demand while we hold the logging
> > mutex.)
> 
> Michal had suggested the same, but I wasn't sure about it since I have a 
> very vague recollection that on a very busy system the system_wq wasn't 
> low-latency enough at high verbosity levels with smaller buffer sizes. 
> However, the same could apply to a dedicated wq and we can now enable 
> bigger log buffers that should significantly reduce the amount of 
> flushes (and thus the latency requirements), so:

We use the system_highpri_wq which should be no different from the
wq we allocated for ourselves. If we need lower latency than that, we
run into trouble :)
-Chris