Am 20.10.2017 um 20:53 schrieb Kasiviswanathan, Harish: > > -----Original Message----- > From: Christian König [mailto:ckoenig.leichtzumerken at gmail.com] > Sent: Friday, October 20, 2017 2:38 PM > To: Kasiviswanathan, Harish <Harish.Kasiviswanathan at amd.com>; amd-gfx at lists.freedesktop.org > Subject: Re: [PATCH v2] drm/amdgpu: Sync KFD fence only for move/evict > > Am 20.10.2017 um 19:18 schrieb Harish Kasiviswanathan: >> A single KFD eviction fence is attached to all the BOs of a process >> including BOs imported. This fence ensures that all BOs belonging to >> that process stays resident when the process queues are active. >> >> Don't add this eviction fence to any sync object unless it is a move >> or evict job. These jobs are identified by the fence owner >> AMDGPU_FENCE_OWNER_UNDEFINED >> >> v2: Always sync to exclusive fence >> >> Change-Id: I8752d1cf6b2a1c4f2a57292b7c2cd308d5b6f9b7 >> Signed-off-by: Harish Kasiviswanathan <Harish.Kasiviswanathan at amd.com> >> --- >> drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c | 8 ++++---- >> 1 file changed, 4 insertions(+), 4 deletions(-) >> >> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c >> b/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c >> index a4f0ecf..88e49f7 100644 >> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c >> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c >> @@ -199,10 +199,10 @@ int amdgpu_sync_resv(struct amdgpu_device *adev, >> return -EINVAL; >> >> f = reservation_object_get_excl(resv); >> - fence_owner = amdgpu_sync_get_owner(f); >> - if (fence_owner != AMDGPU_FENCE_OWNER_KFD || >> - owner != AMDGPU_FENCE_OWNER_VM) >> + if (f) { >> r = amdgpu_sync_fence(adev, sync, f); >> + return r; >> + } > That is not correct either. > > [HK]: I thought resv. object can have either an exclusive fence or shared fences but not both at the same time. Is that correct? No, that assumption is incorrect. A reservation object can has exclusive and shared fences at the same time (and that is actually the normal case). > > It must look like this: >>        /* always sync to the exclusive fence */ >>        f = reservation_object_get_excl(resv); >>        r = amdgpu_sync_fence(adev, sync, f); >> >>        flist = reservation_object_get_list(resv); >>        if (!flist || r) >>                return r > Otherwise you ignore all shared fences and completely mess up the dependencies handling. > > I suggest to just revert the patch which originally changed the code away from what it looks like on amd-staging-drm-next. > > [HK]: This patch is going to 17.40 release branch. There is a serious performance issue in SSG benchmark and this is caused by unnecessary evictions. Please revert that ASAP and get back to how the code looks like on amd-staging-drm-next. Otherwise you completely break correct synchronization. All you need is the hunk below for shared fences. Regards, Christian. > > Regards, > Christian. > > >> >> if (explicit_sync) >> return r; >> @@ -216,7 +216,7 @@ int amdgpu_sync_resv(struct amdgpu_device *adev, >> reservation_object_held(resv)); >> fence_owner = amdgpu_sync_get_owner(f); >> if (fence_owner == AMDGPU_FENCE_OWNER_KFD && >> - owner == AMDGPU_FENCE_OWNER_VM) >> + owner != AMDGPU_FENCE_OWNER_UNDEFINED) >> continue; >> >> if (amdgpu_sync_same_dev(adev, f)) { >
