[AMD Official Use Only - Internal Distribution Only] Thanks! Could you please take an example of trouble “This way we avoid a bunch of trouble when one process drops the VMID reservation and another one grabs it.”? Thanks Jacob From: Koenig, Christian Sent: Tuesday, March 3, 2020 11:03 PM To: He, Jacob; amd-gfx@lists.freedesktop.org Subject: Re: [PATCH] drm/amdgpu: Update SPM_VMID with the job's vmid when application reserves the vmid Am 03.03.20 um 15:34 schrieb He, Jacob: [AMD Official Use Only - Internal Distribution Only] It would be better if we could do that asynchronously with a register write on the ring. Sorry, I don’t get your point. Could you please elaborate more? You pass the ring from amdgpu_vm_flush() to the *_update_spm_vmid() functions. And then instead of using WREG32() you call amdgpu_ring_emit_wreg() to make the write asynchronously on the ring buffer using a CP command. This way we avoid a bunch of trouble when one process drops the VMID reservation and another one grabs it. Regards, Christian. Thanks Jacob From: Christian König Sent: Tuesday, March 3, 2020 10:16 PM To: He, Jacob; amd-gfx@lists.freedesktop.org Subject: Re: [PATCH] drm/amdgpu: Update SPM_VMID with the job's vmid when application reserves the vmid Am 02.03.20 um 06:35 schrieb Jacob He: > SPM access the video memory according to SPM_VMID. It should be updated > with the job's vmid right before the job is scheduled. SPM_VMID is a > global resource > > Change-Id: Id3881908960398f87e7c95026a54ff83ff826700 > Signed-off-by: Jacob He > --- > drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c > index c00696f3017e..c761d3a0b6e8 100644 > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c > @@ -1080,8 +1080,12 @@ int amdgpu_vm_flush(struct amdgpu_ring *ring, struct amdgpu_job *job, > struct dma_fence *fence = NULL; > bool pasid_mapping_needed = false; > unsigned patch_offset = 0; > + bool update_spm_vmid_needed = (job->vm && (job->vm->reserved_vmid[vmhub] != NULL)); > int r; > > + if (update_spm_vmid_needed && adev->gfx.rlc.funcs->update_spm_vmid) > + adev->gfx.rlc.funcs->update_spm_vmid(adev, job->vmid); > + It would be better if we could do that asynchronously with a register write on the ring. The alternative is that we block for the VM to be idle in amdgpu_vm_ioctl() before unreserving the VMID. In other words lock the reservation object of the root PD and call amdgpu_vm_wait_idle() before calling amdgpu_vmid_free_reserved(). Regards, Christian. > if (amdgpu_vmid_had_gpu_reset(adev, id)) { > gds_switch_needed = true; > vm_flush_needed = true;