On Tue, 14 Dec 2021 at 19:19, Christian König
<ckoenig.leichtzumerken@xxxxxxxxx> wrote:
>
> Am 11.12.21 um 10:59 schrieb Stefan Fritsch:
> > On 09.12.21 11:23, Christian König wrote:
> >> Always waiting for the exclusive fence resulted on some performance
> >> regressions. So try to wait for the shared fences first, then the
> >> exclusive fence should always be signaled already.
> >>
> >> v2: fix incorrectly placed "(", add some comment why we do this.
> >>
> >> Signed-off-by: Christian König <christian.koenig@xxxxxxx>
> >
> > Tested-by: Stefan Fritsch <sf@xxxxxxxxxxx>
>
> Thanks.
>
> >
> > Please also add a cc for linux-stable, so that this is fixed in 5.15.x
>
> Sure, but I still need some acked-by or rb from one of the Nouveau guys.
> So gentle ping on that.
Acked-by: Ben Skeggs <bskeggs@xxxxxxxxxx>
>
> Regards,
> Christian.
>
> >
> > Cheers,
> > Stefan
> >
> >> ---
> >> drivers/gpu/drm/nouveau/nouveau_fence.c | 28 +++++++++++++------------
> >> 1 file changed, 15 insertions(+), 13 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/nouveau/nouveau_fence.c
> >> b/drivers/gpu/drm/nouveau/nouveau_fence.c
> >> index 05d0b3eb3690..0ae416aa76dc 100644
> >> --- a/drivers/gpu/drm/nouveau/nouveau_fence.c
> >> +++ b/drivers/gpu/drm/nouveau/nouveau_fence.c
> >> @@ -353,15 +353,22 @@ nouveau_fence_sync(struct nouveau_bo *nvbo,
> >> struct nouveau_channel *chan, bool e
> >> if (ret)
> >> return ret;
> >> - }
> >> - fobj = dma_resv_shared_list(resv);
> >> - fence = dma_resv_excl_fence(resv);
> >> + fobj = NULL;
> >> + } else {
> >> + fobj = dma_resv_shared_list(resv);
> >> + }
> >> - if (fence) {
> >> + /* Waiting for the exclusive fence first causes performance
> >> regressions
> >> + * under some circumstances. So manually wait for the shared
> >> ones first.
> >> + */
> >> + for (i = 0; i < (fobj ? fobj->shared_count : 0) && !ret; ++i) {
> >> struct nouveau_channel *prev = NULL;
> >> bool must_wait = true;
> >> + fence = rcu_dereference_protected(fobj->shared[i],
> >> + dma_resv_held(resv));
> >> +
> >> f = nouveau_local_fence(fence, chan->drm);
> >> if (f) {
> >> rcu_read_lock();
> >> @@ -373,20 +380,13 @@ nouveau_fence_sync(struct nouveau_bo *nvbo,
> >> struct nouveau_channel *chan, bool e
> >> if (must_wait)
> >> ret = dma_fence_wait(fence, intr);
> >> -
> >> - return ret;
> >> }
> >> - if (!exclusive || !fobj)
> >> - return ret;
> >> -
> >> - for (i = 0; i < fobj->shared_count && !ret; ++i) {
> >> + fence = dma_resv_excl_fence(resv);
> >> + if (fence) {
> >> struct nouveau_channel *prev = NULL;
> >> bool must_wait = true;
> >> - fence = rcu_dereference_protected(fobj->shared[i],
> >> - dma_resv_held(resv));
> >> -
> >> f = nouveau_local_fence(fence, chan->drm);
> >> if (f) {
> >> rcu_read_lock();
> >> @@ -398,6 +398,8 @@ nouveau_fence_sync(struct nouveau_bo *nvbo,
> >> struct nouveau_channel *chan, bool e
> >> if (must_wait)
> >> ret = dma_fence_wait(fence, intr);
> >> +
> >> + return ret;
> >> }
> >> return ret;
>
