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

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

btw, what's about gfx9 for amdgpu_vm_ring_has_compute_vm_bug()? Is the
workaround still needed?

On Fri, May 19, 2017 at 10:25:19AM +0800, Flora Cui wrote:
> 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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