Re: [PATCH] drm/amdgpu: fix ocl test performance drop

[Flora Cui <flora.cui-5C7GfCeVMHo@public.gmane.org>]

On Thu, May 18, 2017 at 01:38:15PM +0200, Christian König wrote:
> Am 18.05.2017 um 09:45 schrieb Flora Cui:
> >partial revert commit <6971d3d> - drm/amdgpu: cleanup logic in
> >amdgpu_vm_flush
> >
> >Change-Id: Iadce9d613dfe9a739643a74050cea55854832adb
> >Signed-off-by: Flora Cui <Flora.Cui@amd.com>
> 
> I don't see how the revert should be faster than the original.
> 
> Especially that amdgpu_vm_had_gpu_reset() is now called twice sounds like
> more overhead than necessary.
> 
> Please explain further.
> 
> Christian.
> 
> >---
> >  drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 14 +++++---------
> >  1 file changed, 5 insertions(+), 9 deletions(-)
> >
> >diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> >index 88420dc..a96bad6 100644
> >--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> >+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> >@@ -743,23 +743,19 @@ int amdgpu_vm_flush(struct amdgpu_ring *ring, struct amdgpu_job *job)
> >  		id->gws_size != job->gws_size ||
> >  		id->oa_base != job->oa_base ||
> >  		id->oa_size != job->oa_size);
> >-	bool vm_flush_needed = job->vm_needs_flush ||
> >-		amdgpu_vm_ring_has_compute_vm_bug(ring);
> >  	unsigned patch_offset = 0;
> >  	int r;
> >-	if (amdgpu_vm_had_gpu_reset(adev, id)) {
> >-		gds_switch_needed = true;
> >-		vm_flush_needed = true;
> >-	}
> >-
> >-	if (!vm_flush_needed && !gds_switch_needed)
> >+	if (!job->vm_needs_flush && !gds_switch_needed &&
> >+	    !amdgpu_vm_had_gpu_reset(adev, id) &&
> >+	    !amdgpu_vm_ring_has_compute_vm_bug(ring))
> >  		return 0;
> >  	if (ring->funcs->init_cond_exec)
> >  		patch_offset = amdgpu_ring_init_cond_exec(ring);
> >-	if (ring->funcs->emit_vm_flush && vm_flush_needed) {
[flora]: for compute ring & amdgpu_vm_ring_has_compute_vm_bug(), a vm_flush is
inserted. This might cause performance drop.
> >+	if (ring->funcs->emit_vm_flush &&
> >+	    (job->vm_needs_flush || amdgpu_vm_had_gpu_reset(adev, id))) {
> >  		struct fence *fence;
> >  		trace_amdgpu_vm_flush(ring, job->vm_id, job->vm_pd_addr);
> 
> 
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