[Intel-gfx] [PATCH igt] lib: Ask the kernel to quiescent the GPU

[Petri Latvala]

On Tue, Sep 26, 2017 at 10:02:02AM +0100, Chris Wilson wrote:
> Since the introduction of debugfs/i915_drop_caches, we have offered the
> ability to wait upon all outstanding batches. This is more efficient and
> less error prone (one example is the use of context priorities, we have
> to idle at the lowest in order not to jump over any low priority tasks
> we want to wait upon) than trying to do it all in userspace. Though we
> could if we wanted to, it's just easier to use the existing facility
> designed for the purpose -- that we were already partially using!
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>

After a discussion on IRC regarding kernel backwards compatibility of
DROP_ACTIVE, this LGTM.

Reviewed-by: Petri Latvala <petri.latvala at intel.com>



> ---
>  lib/drmtest.c | 28 +---------------------------
>  1 file changed, 1 insertion(+), 27 deletions(-)
> 
> diff --git a/lib/drmtest.c b/lib/drmtest.c
> index 8a07152c..4ae023d7 100644
> --- a/lib/drmtest.c
> +++ b/lib/drmtest.c
> @@ -159,35 +159,9 @@ static bool has_known_intel_chipset(int fd)
>   */
>  void gem_quiescent_gpu(int fd)
>  {
> -	uint32_t bbe = MI_BATCH_BUFFER_END;
> -	struct drm_i915_gem_execbuffer2 execbuf;
> -	struct drm_i915_gem_exec_object2 obj;
> -	unsigned ring;
> -
>  	igt_terminate_spin_batches();
>  
> -	memset(&obj, 0, sizeof(obj));
> -	obj.handle = gem_create(fd, 4096);
> -	gem_write(fd, obj.handle, 0, &bbe, sizeof(&bbe));
> -
> -	memset(&execbuf, 0, sizeof(execbuf));
> -	execbuf.buffers_ptr = to_user_pointer(&obj);
> -	execbuf.buffer_count = 1;
> -
> -	for (ring = 0; ring < 1<<6; ring++) {
> -		execbuf.flags = ring;
> -		__gem_execbuf(fd, &execbuf);
> -	}
> -
> -	if (gem_has_bsd2(fd)) {
> -		execbuf.flags = I915_EXEC_BSD | (2 << 13);
> -		__gem_execbuf(fd, &execbuf);
> -	}
> -
> -	gem_sync(fd, obj.handle);
> -	gem_close(fd, obj.handle);
> -
> -	igt_drop_caches_set(fd, DROP_RETIRE | DROP_FREED);
> +	igt_drop_caches_set(fd, DROP_ACTIVE | DROP_RETIRE | DROP_FREED);
>  }
>  
>  /**
> -- 
> 2.14.1
> 
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