Re: [Intel-gfx] [PATCH v3] drm/i915: Don't show engine information in fdinfo with GuC submission

["Dixit, Ashutosh" <ashutosh.dixit@intel.com>]

On Wed, 27 Apr 2022 02:15:35 -0700, Tvrtko Ursulin wrote:
>
> On 15/04/2022 01:25, Ashutosh Dixit wrote:
> > At present i915 does not fetch busyness information from GuC, resulting in
> > incorrect busyness values in fdinfo. Because engine information is coupled
> > with busyness in fdinfo, skip showing client engine information in fdinfo
> > with GuC submission till fetching busyness is supported in the i915 GuC
> > submission backend.
> >
> > v2 (Daniele):
> >    Make commit title and description more precise
> >    Add FIXME with brief description at code change
> >    s/intel_guc_submission_is_used/intel_uc_uses_guc_submission/
> >
> > v3 (Daniele):
> >    Drop FIXME in comment
> >
> > Bug: https://gitlab.freedesktop.org/drm/intel/-/issues/5564
> > Fixes: 055634e4b62f ("drm/i915: Expose client engine utilisation via fdinfo")
> > Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com
> > Cc: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
> > Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
> > Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
> > ---
> >   drivers/gpu/drm/i915/i915_drm_client.c | 6 +++++-
> >   1 file changed, 5 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_drm_client.c b/drivers/gpu/drm/i915/i915_drm_client.c
> > index e539f6b23060..475a6f824cad 100644
> > --- a/drivers/gpu/drm/i915/i915_drm_client.c
> > +++ b/drivers/gpu/drm/i915/i915_drm_client.c
> > @@ -145,7 +145,11 @@ void i915_drm_client_fdinfo(struct seq_file *m, struct file *f)
> >		   PCI_SLOT(pdev->devfn), PCI_FUNC(pdev->devfn));
> >	seq_printf(m, "drm-client-id:\t%u\n", client->id);
> >   -	if (GRAPHICS_VER(i915) < 8)
> > +	/*
> > +	 * Temporarily skip showing client engine information with GuC submission till
> > +	 * fetching engine busyness is implemented in the GuC submission backend
> > +	 */
> > +	if (GRAPHICS_VER(i915) < 8 || intel_uc_uses_guc_submission(&i915->gt0.uc))
> >		return;
> >		for (i = 0; i < ARRAY_SIZE(uabi_class_names); i++)
>
> Thanks for fixing this while I was away. It was a simple miss, nothing
> sinister. In terms of mention of "garbage" numbers being reported - were
> they actually garbage or simply always zero?

Ah, you are referring to what I wrote in the bug. Actually I didn't check
the values myself but was told we were displaying "garbage" values (or at
least I interpreted it that way, and garbage meaning not just zero). But
looking now at IGT outputs from that time appears the values were just zero
:/

https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_11503/re-adlp-pub1/igt@drm_fdinfo@all-busy-idle-check-all.html

I think we could even have left zero values as is except that we'd have to
fix the IGT failure.

Sorry for the confusion.

Thanks.
--
Ashutosh