On Tue, Oct 22, 2024 at 10:24 AM Chia-I Wu <olvaffe@xxxxxxxxx> wrote: > > On Tue, Oct 22, 2024 at 9:53 AM Christian König > <christian.koenig@xxxxxxx> wrote: > > > > Am 22.10.24 um 18:18 schrieb Chia-I Wu: > > > Userspace might poll a syncobj with the query ioctl. Call > > > dma_fence_enable_sw_signaling to ensure dma_fence_is_signaled returns > > > true in finite time. > > > > Wait a second, just querying the fence status is absolutely not > > guaranteed to return true in finite time. That is well documented on the > > dma_fence() object. > > > > When you want to poll on signaling from userspace you really need to > > call poll or the wait IOCTL with a zero timeout. That will also return > > immediately but should enable signaling while doing that. > > > > So just querying the status should absolutely *not* enable signaling. > > That's an intentional separation. > I think it depends on what semantics DRM_IOCTL_SYNCOBJ_QUERY should have. > > If DRM_IOCTL_SYNCOBJ_QUERY is mainly for vulkan timeline semaphores, > it is a bit heavy if userspace has to do a > DRM_IOCTL_SYNCOBJ_TIMELINE_WAIT before a query. I filed a Mesa issue, https://gitlab.freedesktop.org/mesa/mesa/-/issues/12094, and Faith suggested a kernel-side fix as well. Should we reconsider this?
