If the fence context has notifies enabled, each of the fences' FENCE_FLAG_SIGNALED_BIT will be updated from the interrupt. We can rely on this status for reporting the current fence_is_signaled() and so avoid an expensive uncached read. Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Cc: Ben Skeggs <bskeggs@xxxxxxxxxx> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx Cc: nouveau@xxxxxxxxxxxxxxxxxxxxx --- drivers/gpu/drm/nouveau/nouveau_fence.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/gpu/drm/nouveau/nouveau_fence.c b/drivers/gpu/drm/nouveau/nouveau_fence.c index 4bb9ab892ae1..7daed5c33043 100644 --- a/drivers/gpu/drm/nouveau/nouveau_fence.c +++ b/drivers/gpu/drm/nouveau/nouveau_fence.c @@ -510,6 +510,16 @@ static bool nouveau_fence_is_signaled(struct fence *f) struct nouveau_channel *chan; bool ret = false; + /* If the notify is already active, we can rely on + * FENCE_FLAG_SIGNALED_BIT being accurate and skip checking the + * current seqno as fctx->read() requires an expensive uncached read. + */ + if (test_bit(FENCE_FLAG_USER_BITS, &fence->base.flags)) + return false; + + if (READ_ONCE(fctx->notify_ref)) + return false; + rcu_read_lock(); chan = rcu_dereference(fence->channel); if (chan) -- 2.9.3 _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
