| Message ID | 20230227193535.2822389-7-robdclark@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | dma-fence: Deadline awareness | expand |
On Mon, 27 Feb 2023 11:35:12 -0800 Rob Clark <robdclark@gmail.com> wrote: > From: Rob Clark <robdclark@chromium.org> > > Allow userspace to use the EPOLLPRI/POLLPRI flag to indicate an urgent > wait (as opposed to a "housekeeping" wait to know when to cleanup after > some work has completed). Usermode components of GPU driver stacks > often poll() on fence fd's to know when it is safe to do things like > free or reuse a buffer, but they can also poll() on a fence fd when > waiting to read back results from the GPU. The EPOLLPRI/POLLPRI flag > lets the kernel differentiate these two cases. > > Signed-off-by: Rob Clark <robdclark@chromium.org> > --- > drivers/dma-buf/sync_file.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c > index 418021cfb87c..cbe96295373b 100644 > --- a/drivers/dma-buf/sync_file.c > +++ b/drivers/dma-buf/sync_file.c > @@ -192,6 +192,14 @@ static __poll_t sync_file_poll(struct file *file, poll_table *wait) > { > struct sync_file *sync_file = file->private_data; > > + /* > + * The POLLPRI/EPOLLPRI flag can be used to signal that > + * userspace wants the fence to signal ASAP, express this > + * as an immediate deadline. > + */ > + if (poll_requested_events(wait) & EPOLLPRI) > + dma_fence_set_deadline(sync_file->fence, ktime_get()); Hi, I don't think this doc will appear anywhere where it could be found, maybe not in kernel HTML doc at all? I also think this is not a good idea, but not my call. Thanks, pq > + > poll_wait(file, &sync_file->wq, wait); > > if (list_empty(&sync_file->cb.node) &&
diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c index 418021cfb87c..cbe96295373b 100644 --- a/drivers/dma-buf/sync_file.c +++ b/drivers/dma-buf/sync_file.c @@ -192,6 +192,14 @@ static __poll_t sync_file_poll(struct file *file, poll_table *wait) { struct sync_file *sync_file = file->private_data; + /* + * The POLLPRI/EPOLLPRI flag can be used to signal that + * userspace wants the fence to signal ASAP, express this + * as an immediate deadline. + */ + if (poll_requested_events(wait) & EPOLLPRI) + dma_fence_set_deadline(sync_file->fence, ktime_get()); + poll_wait(file, &sync_file->wq, wait); if (list_empty(&sync_file->cb.node) &&