On 01/08/2019 18:16, Chris Wilson wrote:
Quoting Lionel Landwerlin (2019-08-01 15:29:34)
On 31/07/2019 23:03, Chris Wilson wrote:
Quoting Lionel Landwerlin (2019-07-31 15:07:33)
...
I think I have convinced myself that with the split between wait before,
signal after combined with the rule that seqno point along the syncobj
are monotonic, you should not be able to generate an AB-BA deadlock
between concurrent clients.
Can you come up with an example that would deadlock?
Timeline holds 2,1; a wait on 2 will fail with -EINVAL to userspace.
(Though possibly perfectly valid behaviour on the part of the user.)
Timeline holds 2, with 1 being submitted. A wait on 1 waits on 2
instead. If 1 gains a dependency on A (e.g. bad userspace or an
You mean : 1 gains a dependency on 2?
implicit fence, it's a concurrent wait/submit so expect the worst, i.e.
userspace has to be racing with itself to get into this mess), you
now have a deadlock.
Not quite sure I see why...
2 doesn't have any dependency on 1, it just happens to have a number higher.
-Lionel
(The assumption being that the syncpt along the
timeline are themselves not strictly ordered, and considering they are
external syncobj, that seems like a reasonable generalisation.)
-Chris
_______________________________________________
Intel-gfx mailing list
Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/intel-gfx
