On 2023-06-01 18:06, James Zhu wrote:
On 2023-06-01 17:17, Felix Kuehling wrote:
On 2023-06-01 16:47, James Zhu wrote:
Don't sleep when event age unmatch, and update last_event_age.
It is only for KFD_EVENT_TYPE_SIGNAL which is checked by user space.
Signed-off-by: James Zhu <James.Zhu@xxxxxxx>
---
drivers/gpu/drm/amd/amdkfd/kfd_events.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_events.c
b/drivers/gpu/drm/amd/amdkfd/kfd_events.c
index b27a79c5f826..23e154811471 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_events.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_events.c
@@ -964,6 +964,19 @@ int kfd_wait_on_events(struct kfd_process *p,
event_data.event_id);
if (ret)
goto out_unlock;
+
+ /* last_event_age = 0 reserved for backward compatible */
+ if (event_data.last_event_age &&
+ event_waiters[i].event->event_age !=
event_data.last_event_age) {
+ event_data.last_event_age =
event_waiters[i].event->event_age;
+ WRITE_ONCE(event_waiters[i].activated, true);
I think this is probably not necessary if you're returning before the
first call to test_event_condition.
[JZ] Currently, the returning is with test_event_condition. Since some
conditions needs return with all events signaled.
so all waiters need check and update if any event interrupts are
missing here(unmatched event age).
+
+ if (copy_to_user(&events[i], &event_data,
+ sizeof(struct kfd_event_data))) {
+ ret = -EFAULT;
+ goto out_unlock;
+ }
+ }
When waiting on multiple events, it would be more efficient to catch
all events with outdated age in a single system call, instead of
returning after finding the first one. Then return after the loop if
it found one or more outdated events.
[JZ] Yes, the code is working in this way, when all events' waiters
are activated, the following test_event_condition ==
KFD_IOC_WAIT_RESULT_COMPLETE, then return to user mode without sleep.
Also EFAULT is the wrong error code. It means "bad address". I think
we could return 0 here because there is really no error. It's just a
normal condition to allow user mode to update its event information
before going to sleep. If you want a non-0 return code, I'd recommend
-EDEADLK, because sleeping without outdated event information can
lead to deadlocks. We'd also need to translate that into a meaningful
status code in the Thunk to let ROCr know what's going on. I don't
see a suitable status code in the current Thunk API for this.
[JZ] Basically, this failure is for copy_to_user. It will lead to busy
wait instead of deadlock.
Oh, right, I missed that this is only for the case that copy_to_user
fails. EFAULT is the correct error code for this. Then this patch looks
good as is.
Regards,
Felix
**
Regards,
Felix
}
/* Check condition once. */
