Re: [PATCH i-g-t v5] tests/i915/gem_exec_async: Update with engine discovery

[Ramalingam C <ramalingam.c@intel.com>]

On 2019-07-30 at 13:05:27 +0100, Tvrtko Ursulin wrote:
> 
> On 30/07/2019 04:58, Ramalingam C wrote:
> > Legacy execbuf abi tests are prefixed with legacy. New test are added to
> > run on physical engines accessed through engine discovery.
> > 
> > So legacy tests run on the unconfigured (with engine map) context and
> > use a new helper gem_eb_flags_to_engine to look up the engine from the
> > intel_execution_engines2 static list. This is only to enable the core
> > test code to be shared.
> > 
> > Places where new contexts are created had to be updated to either
> > equally configure the contexts or not.
> > 
> > v2:
> >    retained the test as it is for legacy uapi testing and duplciated for
> > 	new engine discovery [Tvrtko]
> > v3:
> >    Few nits addressed [Tvrtko]
> > v4:
> >    In legacy uAPI test path, iterate through for_each_engine [Tvrtko]
> > v5:
> >    Function for exec_flag comparison [Tvrtko]
> > 
> > Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
> > ---
> >   lib/igt_gt.c                | 25 ++++++++++++++++++
> >   lib/igt_gt.h                |  1 +
> >   tests/i915/gem_exec_async.c | 52 +++++++++++++++++++++++++++----------
> >   3 files changed, 64 insertions(+), 14 deletions(-)
> > 
> > diff --git a/lib/igt_gt.c b/lib/igt_gt.c
> > index 78e3cd08925b..f594a46282bc 100644
> > --- a/lib/igt_gt.c
> > +++ b/lib/igt_gt.c
> > @@ -633,3 +633,28 @@ bool gem_ring_has_physical_engine(int fd, unsigned ring)
> >   
> >   	return gem_has_ring(fd, ring);
> >   }
> > +
> > +bool gem_eb_flags_are_different_engines(unsigned eb_flag1, unsigned eb_flag2)
> 
> I think we try to avoid implied int but not sure in this case whether to suggest unsigned int, long or uint64_t. If we are suggesting in the function name that any flags can be passed in perhaps it should be uint64_t and then we filter on the engine bits (flags.. &= I915_EXEC_RING_MASK | (3 << 13)) before checking. Yeah, I think that would be more robust for a generic helper.
> 
> And add a doc blurb for this helper since it is non-obvious why we went for different and not same. My thinking was the name different would be clearer to express kind of tri-state nature of this check. (Flags may be different, but engines are not guaranteed to be different.) Have I over-complicated it? Do we need to make it clearer by naming it gem_eb_flags_are_guaranteed_different_engines? :)
For me current shape looks good enough :) I will use the uint64_t for
parameter types.
> 
> > +{
> > +	if (eb_flag1 == eb_flag2)
> > +		return false;
> > +
> > +	/* DEFAULT stands for RENDER in legacy uAPI*/
> > +	if ((eb_flag1 == I915_EXEC_DEFAULT && eb_flag2 == I915_EXEC_RENDER) ||
> > +	     (eb_flag1 == I915_EXEC_RENDER && eb_flag2 == I915_EXEC_DEFAULT))
> > +		return false;
> > +
> > +	/*
> > +	 * BSD could be executed on BSD1/BSD2. So BSD and BSD-n could be
> > +	 * same engine.
> > +	 */
> > +	if ((eb_flag1 == I915_EXEC_BSD) &&
> > +	    (eb_flag2 & ~I915_EXEC_BSD_MASK) == I915_EXEC_BSD)
> > +			return false;
> > +
> > +	if ((eb_flag2 == I915_EXEC_BSD) &&
> > +	    (eb_flag1 & ~I915_EXEC_BSD_MASK) == I915_EXEC_BSD)
> > +			return false;
> 
> I think this works.
> 
> I've also come up with something to merge the two checks, not 100% it's correct or more readable:
> 
> if (((flag1 | flag2) & I915_EXEC_RING_MASK)) == I915_EXEC_BSD && // at least one is BSD
>     !((flag1 ^ flag2) & I915_EXEC_RING_MASK) && // both are BSD
>     (((flag1 | flag2) & (3 << 13))) != 3) // not guaranteed different
> 	return false;
> 
> Would need feeding in some values and checking it works as expected. Probably not worth it since I doubt it is more readable.
readability perspective, we could stick to the original version. If we
want to go ahead we need to do below ops:

if (((flag1 | flag2) & I915_EXEC_BSD) &&  //Atleast one is BSD
    !((flag1 ^ flag2) & I915_EXEC_BSD) && //Both are BSD
    ((flag1 | flag2) & I915_EXEC_RING_MASK) != I915_EXEC_RING_MASK) //Not BSD0 and BSD1
	return false;
> 
> > +
> > +	return true;
> > +}
> > diff --git a/lib/igt_gt.h b/lib/igt_gt.h
> > index 73b5002a04bd..760b8baefc48 100644
> > --- a/lib/igt_gt.h
> > +++ b/lib/igt_gt.h
> > @@ -101,5 +101,6 @@ extern const struct intel_execution_engine2 {
> >   } intel_execution_engines2[];
> >   
> >   int gem_execbuf_flags_to_engine_class(unsigned int flags);
> > +bool gem_eb_flags_are_different_engines(unsigned eb_flag1, unsigned eb_flag2);
> >   
> >   #endif /* IGT_GT_H */
> > diff --git a/tests/i915/gem_exec_async.c b/tests/i915/gem_exec_async.c
> > index 9a06af7e29cb..5fdce5ac5b77 100644
> > --- a/tests/i915/gem_exec_async.c
> > +++ b/tests/i915/gem_exec_async.c
> > @@ -80,9 +80,10 @@ static void store_dword(int fd, unsigned ring,
> >   	gem_close(fd, obj[1].handle);
> >   }
> >   
> > -static void one(int fd, unsigned ring, uint32_t flags)
> > +static void one(int fd, const struct intel_execution_engine2 *e2, bool legacy)
> >   {
> >   	const int gen = intel_gen(intel_get_drm_devid(fd));
> > +	const struct intel_execution_engine2 *other2;
> >   	struct drm_i915_gem_exec_object2 obj[2];
> >   #define SCRATCH 0
> >   #define BATCH 1
> > @@ -138,20 +139,33 @@ static void one(int fd, unsigned ring, uint32_t flags)
> >   	memset(&execbuf, 0, sizeof(execbuf));
> >   	execbuf.buffers_ptr = to_user_pointer(obj);
> >   	execbuf.buffer_count = 2;
> > -	execbuf.flags = ring | flags;
> > +	execbuf.flags = e2->flags;
> >   	igt_require(__gem_execbuf(fd, &execbuf) == 0);
> >   	gem_close(fd, obj[BATCH].handle);
> >   
> >   	i = 0;
> > -	for_each_physical_engine(fd, other) {
> > -		if (other == ring)
> > -			continue;
> > +	if (legacy) {
> > +		for_each_engine(fd, other) {
> > +			if (gem_eb_flags_are_different_engines(e2->flags, other))
> 
> if (!different)
Will fix it. Thanks.

-Ram
> 
> Regards,
> 
> Tvrtko
> 
> > +				continue;
> >   
> > -		if (!gem_can_store_dword(fd, other))
> > -			continue;
> > +			if (!gem_can_store_dword(fd, other))
> > +				continue;
> > +
> > +			store_dword(fd, other, obj[SCRATCH].handle, 4*i, i);
> > +			i++;
> > +		}
> > +	} else {
> > +		__for_each_physical_engine(fd, other2) {
> > +			if (gem_engine_is_equal(e2, other2))
> > +				continue;
> >   
> > -		store_dword(fd, other, obj[SCRATCH].handle, 4*i, i);
> > -		i++;
> > +			if (!gem_class_can_store_dword(fd, other2->class))
> > +				continue;
> > +
> > +			store_dword(fd, other2->flags, obj[SCRATCH].handle, 4*i, i);
> > +			i++;
> > +		}
> >   	}
> >   
> >   	*batch = MI_BATCH_BUFFER_END;
> > @@ -185,7 +199,9 @@ static bool has_async_execbuf(int fd)
> >   
> >   igt_main
> >   {
> > +	const struct intel_execution_engine2 *e2;
> >   	const struct intel_execution_engine *e;
> > +	struct intel_execution_engine2 e2__;
> >   	int fd = -1;
> >   
> >   	igt_skip_on_simulation();
> > @@ -200,14 +216,22 @@ igt_main
> >   	}
> >   
> >   	for (e = intel_execution_engines; e->name; e++) {
> > -		/* default exec-id is purely symbolic */
> > -		if (e->exec_id == 0)
> > +		e2__ = gem_eb_flags_to_engine(e->exec_id | e->flags);
> > +		if (e2__.flags == -1)
> >   			continue;
> > +		e2 = &e2__;
> >   
> > -		igt_subtest_f("concurrent-writes-%s", e->name) {
> > +		igt_subtest_f("legacy-concurrent-writes-%s", e2->name) {
> >   			igt_require(gem_ring_has_physical_engine(fd, e->exec_id | e->flags));
> > -			igt_require(gem_can_store_dword(fd, e->exec_id | e->flags));
> > -			one(fd, e->exec_id, e->flags);
> > +			igt_require(gem_class_can_store_dword(fd, e2->class));
> > +			one(fd, e2, true);
> > +		}
> > +	}
> > +
> > +	__for_each_physical_engine(fd, e2) {
> > +		igt_subtest_f("concurrent-writes-%s", e2->name) {
> > +			igt_require(gem_class_can_store_dword(fd, e2->class));
> > +			one(fd, e2, false);
> >   		}
> >   	}
> >   
> > 
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