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

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 27/04/2022 16:43, Dixit, Ashutosh wrote:
> 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.

Np. One could even say that there is little difference between skip and 
fail, given both need manual handling in cibuglog to be marked as known 
until GuC support gets added. At least if I still remember how it works 
and that unexplained skips still count as fails.

Regards,

Tvrtko