[Intel-gfx] [PATCH 1/2] drm/i915/guc: Add GuC Load time to debugfs

[Chris Wilson]

Quoting Srivatsa, Anusha (2017-09-08 18:58:11)
> 
> 
> >-----Original Message-----
> >From: Chris Wilson [mailto:chris at chris-wilson.co.uk]
> >Sent: Thursday, September 7, 2017 3:08 PM
> >To: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>; Srivatsa, Anusha
> ><anusha.srivatsa at intel.com>; intel-gfx at lists.freedesktop.org
> >Cc: Sundaresan, Sujaritha <sujaritha.sundaresan at intel.com>
> >Subject: Re: [Intel-gfx] [PATCH 1/2] drm/i915/guc: Add GuC Load time to debugfs
> >
> >Quoting Tvrtko Ursulin (2017-09-07 09:49:02)
> >>
> >> On 07/09/2017 01:37, Anusha Srivatsa wrote:
> >> > Calculate the time that GuC takes to load.
> >> > This information could be very useful in determining if GuC is
> >> > taking unreasonably long time to load in a certain platforms.
> >>
> >> Do we need this in debugfs or a DRM_NOTE or something would be
> >> sufficient if the load time is above certain threshold?
> >>
> >> Also, what are the typical times here? Are jiffies precise enough?
> >> Could be only 10ms granularity on some kernels.
> >
> >Hear, hear. Aiming for jiffie resolution sets a very low bar.
> >
> >Why is this important anyway? It shouldn't be on the critical path for bringing up
> >userspace (i.e. on the synchronous portion of boot/module loading). Nor should
> >it be delaying bringing up a screen, once the core is initialised we should be able
> >to bring up GT and the display in parallel.
> 
> Hi Chris,
> Wont it still be of some value to know the time taken to load the firmware in different platforms? To have some data to tell how much time it takes to load?

If it always reports 0 jiffies that is not much use. Why do you need to
add code to do this since you can just log the function call timings?
-Chris