[Public]
Regards,
Prike
> -----Original Message-----
> From: Koenig, Christian <[email protected]>
> Sent: Tuesday, March 17, 2026 7:23 PM
> To: Liang, Prike <[email protected]>; [email protected]; Deucher,
> Alexander
> <[email protected]>; Mohan Marimuthu, Yogesh
> <[email protected]>; SHANMUGAM, SRINIVASAN
> <[email protected]>; Khatri, Sunil <[email protected]>;
> [email protected]
> Subject: Re: [PATCH 04/11] drm/amdgpu: completely rework eviction fence
> handling
>
> On 3/17/26 12:21, Liang, Prike wrote:
> > [Public]
> >
> > Regards,
> > Prike
> >
> >> -----Original Message-----
> >> From: Koenig, Christian <[email protected]>
> >> Sent: Tuesday, March 17, 2026 5:57 PM
> >> To: Liang, Prike <[email protected]>; [email protected];
> >> Deucher, Alexander <[email protected]>; Mohan Marimuthu,
> >> Yogesh <[email protected]>; SHANMUGAM, SRINIVASAN
> >> <[email protected]>; Khatri, Sunil
> <[email protected]>;
> >> [email protected]
> >> Subject: Re: [PATCH 04/11] drm/amdgpu: completely rework eviction
> >> fence handling
> >>
> >> On 3/13/26 09:28, Liang, Prike wrote:
> >>>> +void amdgpu_evf_mgr_attach_fence(struct amdgpu_eviction_fence_mgr
> >> *evf_mgr,
> >>>> + struct amdgpu_bo *bo) {
> >>>> + struct dma_fence *ev_fence = amdgpu_evf_mgr_get_fence(evf_mgr);
> >>>> + struct dma_resv *resv = bo->tbo.base.resv;
> >>>
> >>> Before adding the attached fence, there requires allocating the
> >>> reservation fence
> >> slot first.
> >>
> >> No, the caller does that using the drm_exec.
> >>
> >> Additional to that it is way to late to do any memory allocation here
> >> since that could cycle back and wait for us to attach the eviction fence.
> >>
> >> So by reserving a slot here you would just create a potential deadlock.
> >
> > Is possible pass the wrong fence number through the
> amdgpu_vm_lock_pd()/drm_exec_prepare_obj()? I saw the fence number assert
> error during attaching the reservation fence.
>
> Yeah that is perfectly possible.
>
> For kernel queues you need to have something like number_of_gang_members + 1
> (for TTM) + 1 (for page table updates).
>
> For user queues we probably need 1 (for TTM) + 1 (for page tables updates) +
> 1 (for
> the eviction fence).
>
> Not sure if the calculation was really correct.
We may need to reserve one extra fence slot for attaching eviction fence to the
root BO in the amdgpu_gem_object_open().
> Regards,
> Christian.
>
> >
> >> Regards,
> >> Christian.
