[Intel-gfx] [PATCH i-g-t] tests/i915: Skip gem_exec_fair on GuC based platforms

[Intel-gfx] [PATCH i-g-t] tests/i915: Skip gem_exec_fair on GuC based platforms

[John.C.Harrison]

From: John Harrison <John.C.Harrison@Intel.com>

The gem_exec_fair test is specifically testing scheduler algorithm
performance. However, GuC does not implement the same algorithm as
execlist mode and this test is not applicable. So, until sw arch
approves a new algorithm and it is implemented in GuC, stop running
the test.

Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
---
 tests/i915/gem_exec_fair.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/tests/i915/gem_exec_fair.c b/tests/i915/gem_exec_fair.c
index ef5a450f6..ca9c73c6e 100644
--- a/tests/i915/gem_exec_fair.c
+++ b/tests/i915/gem_exec_fair.c
@@ -1314,6 +1314,12 @@ igt_main
 		igt_require(gem_scheduler_enabled(i915));
 		igt_require(gem_scheduler_has_ctx_priority(i915));
 
+		/*
+		 * These tests are for a specific scheduling model which is
+		 * not currently implemented by GuC. So skip on GuC platforms.
+		 */
+		igt_require(intel_gen(intel_get_drm_devid(i915)) < 12);
+
 		cfg = intel_ctx_cfg_all_physical(i915);
 
 		igt_info("CS timestamp frequency: %d\n",
-- 
2.25.1

Re: [Intel-gfx] [PATCH i-g-t] tests/i915: Skip gem_exec_fair on GuC based platforms

[Dixit, Ashutosh]

On Wed, 13 Oct 2021 15:43:17 -0700, <John.C.Harrison@Intel.com> wrote:
>
> From: John Harrison <John.C.Harrison@Intel.com>
>
> The gem_exec_fair test is specifically testing scheduler algorithm
> performance. However, GuC does not implement the same algorithm as
> execlist mode and this test is not applicable. So, until sw arch
> approves a new algorithm and it is implemented in GuC, stop running
> the test.
>
> Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
> ---
>  tests/i915/gem_exec_fair.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/tests/i915/gem_exec_fair.c b/tests/i915/gem_exec_fair.c
> index ef5a450f6..ca9c73c6e 100644
> --- a/tests/i915/gem_exec_fair.c
> +++ b/tests/i915/gem_exec_fair.c
> @@ -1314,6 +1314,12 @@ igt_main
>		igt_require(gem_scheduler_enabled(i915));
>		igt_require(gem_scheduler_has_ctx_priority(i915));
>
> +		/*
> +		 * These tests are for a specific scheduling model which is
> +		 * not currently implemented by GuC. So skip on GuC platforms.
> +		 */
> +		igt_require(intel_gen(intel_get_drm_devid(i915)) < 12);

Probably a feature check rather than a version check is better? Can we use
say gem_has_guc_submission() instead?

Though appears gem_has_guc_submission() only checks if guc submission is
available, not if it is actually in use (unless guc will used when
available automatically)? Is it possible to add the check if guc submission
is actually in use? Or a check for guc scheduler?

> +
>		cfg = intel_ctx_cfg_all_physical(i915);
>
>		igt_info("CS timestamp frequency: %d\n",
> --
> 2.25.1
>

Re: [Intel-gfx] [PATCH i-g-t] tests/i915: Skip gem_exec_fair on GuC based platforms

[John Harrison]

On 10/13/2021 15:53, Dixit, Ashutosh wrote:
> On Wed, 13 Oct 2021 15:43:17 -0700, <John.C.Harrison@Intel.com> wrote:
>> From: John Harrison <John.C.Harrison@Intel.com>
>>
>> The gem_exec_fair test is specifically testing scheduler algorithm
>> performance. However, GuC does not implement the same algorithm as
>> execlist mode and this test is not applicable. So, until sw arch
>> approves a new algorithm and it is implemented in GuC, stop running
>> the test.
>>
>> Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
>> ---
>>   tests/i915/gem_exec_fair.c | 6 ++++++
>>   1 file changed, 6 insertions(+)
>>
>> diff --git a/tests/i915/gem_exec_fair.c b/tests/i915/gem_exec_fair.c
>> index ef5a450f6..ca9c73c6e 100644
>> --- a/tests/i915/gem_exec_fair.c
>> +++ b/tests/i915/gem_exec_fair.c
>> @@ -1314,6 +1314,12 @@ igt_main
>> 		igt_require(gem_scheduler_enabled(i915));
>> 		igt_require(gem_scheduler_has_ctx_priority(i915));
>>
>> +		/*
>> +		 * These tests are for a specific scheduling model which is
>> +		 * not currently implemented by GuC. So skip on GuC platforms.
>> +		 */
>> +		igt_require(intel_gen(intel_get_drm_devid(i915)) < 12);
> Probably a feature check rather than a version check is better? Can we use
> say gem_has_guc_submission() instead?
>
> Though appears gem_has_guc_submission() only checks if guc submission is
> available, not if it is actually in use (unless guc will used when
> available automatically)? Is it possible to add the check if guc submission
> is actually in use? Or a check for guc scheduler?
I believe this has come up a few times before. My understanding is that 
no, there is no current official/safe way for userland to check if GuC 
submission is enabled (you can read some of the debugfs files and make 
an educated guess but that isn't exactly an official interface). And the 
answer was that it isn't worth adding a UAPI specifically for it. Not 
least because it would be a UAPI solely for use by IGT which is not allowed.

John.


>
>> +
>> 		cfg = intel_ctx_cfg_all_physical(i915);
>>
>> 		igt_info("CS timestamp frequency: %d\n",
>> --
>> 2.25.1
>>

Re: [Intel-gfx] [PATCH i-g-t] tests/i915: Skip gem_exec_fair on GuC based platforms

[Dixit, Ashutosh]

On Wed, 13 Oct 2021 18:07:05 -0700, John Harrison wrote:
>
> On 10/13/2021 15:53, Dixit, Ashutosh wrote:
> >> diff --git a/tests/i915/gem_exec_fair.c b/tests/i915/gem_exec_fair.c
> >> index ef5a450f6..ca9c73c6e 100644
> >> --- a/tests/i915/gem_exec_fair.c
> >> +++ b/tests/i915/gem_exec_fair.c
> >> @@ -1314,6 +1314,12 @@ igt_main
> >>		igt_require(gem_scheduler_enabled(i915));
> >>		igt_require(gem_scheduler_has_ctx_priority(i915));
> >>
> >> +		/*
> >> +		 * These tests are for a specific scheduling model which is
> >> +		 * not currently implemented by GuC. So skip on GuC platforms.
> >> +		 */
> >> +		igt_require(intel_gen(intel_get_drm_devid(i915)) < 12);
> > Probably a feature check rather than a version check is better? Can we use
> > say gem_has_guc_submission() instead?
> >
> > Though appears gem_has_guc_submission() only checks if guc submission is
> > available, not if it is actually in use (unless guc will used when
> > available automatically)? Is it possible to add the check if guc submission
> > is actually in use? Or a check for guc scheduler?
>
> I believe this has come up a few times before. My understanding is that no,
> there is no current official/safe way for userland to check if GuC
> submission is enabled (you can read some of the debugfs files and make an
> educated guess but that isn't exactly an official interface). And the
> answer was that it isn't worth adding a UAPI specifically for it. Not least
> because it would be a UAPI solely for use by IGT which is not allowed.

Hmm, so kernel will use GuC submission if bit 0 of enable_guc module param
is 1, correct? Which is what gem_has_guc_submission() checks, though I
guess we can also add a function gem_using_guc_submission() which is
basically an alias for gem_has_guc_submission(). So we can't do this? Or
the module param is not an acceptable uapi? But we already introduced
gem_has_guc_submission()?

I think this kind of a generation/version check should be implemented in
the kernel. If kernel wants to turn on GuC submission by default let it do
that and set enable_guc. In IGT we just check enable_guc. No? Thanks.

Re: [Intel-gfx] [igt-dev] [PATCH i-g-t] tests/i915: Skip gem_exec_fair on GuC based platforms

[Tvrtko Ursulin]

On 13/10/2021 23:43, John.C.Harrison@Intel.com wrote:
> From: John Harrison <John.C.Harrison@Intel.com>
> 
> The gem_exec_fair test is specifically testing scheduler algorithm
> performance. However, GuC does not implement the same algorithm as
> execlist mode and this test is not applicable. So, until sw arch
> approves a new algorithm and it is implemented in GuC, stop running
> the test.
> 
> Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
> ---
>   tests/i915/gem_exec_fair.c | 6 ++++++
>   1 file changed, 6 insertions(+)
> 
> diff --git a/tests/i915/gem_exec_fair.c b/tests/i915/gem_exec_fair.c
> index ef5a450f6..ca9c73c6e 100644
> --- a/tests/i915/gem_exec_fair.c
> +++ b/tests/i915/gem_exec_fair.c
> @@ -1314,6 +1314,12 @@ igt_main
>   		igt_require(gem_scheduler_enabled(i915));
>   		igt_require(gem_scheduler_has_ctx_priority(i915));
>   
> +		/*
> +		 * These tests are for a specific scheduling model which is
> +		 * not currently implemented by GuC. So skip on GuC platforms.
> +		 */
> +		igt_require(intel_gen(intel_get_drm_devid(i915)) < 12);

I don't understand why do patches which claim Tigerlake is a GuC 
submission platform keep appearing?

It's a stupid patch to use it against, but as a matter of principle this 
has to receive a clear NACK, from me at least.

There are so many ways to avoid the nack, but factually incorrect commit 
message and code comment just have no place so IMO cannot go in.

We can look at on which platforms it passes and on which platforms it 
mostly fails and decide what to do about it.

Or just use debugfs to check whether GuC is in use, IGT does it all the 
time and it's not ABI. Or improve the skip condition to include gen 
_and_ _platform_ checks.

Anything but proposing patches which are factually incorrect.

Regards,

Tvrtko

> +
>   		cfg = intel_ctx_cfg_all_physical(i915);
>   
>   		igt_info("CS timestamp frequency: %d\n",
>