On 3/4/24 22:07, Pavel Begunkov wrote:
On 3/1/24 03:45, Jens Axboe wrote:
On 2/29/24 9:36 AM, Pavel Begunkov wrote:
With defer taskrun we store aux cqes into a cache array and then flush
into the CQ, and we also maintain the ordering so aux cqes are flushed
before request completions. Why do we need the cache instead of pushing
them directly? We acutally don't, so let's kill it.
One nuance is synchronisation -- the path we touch here is only for
DEFER_TASKRUN and guaranteed to be executed in the task context, and
all cqe posting is serialised by that. We also don't need locks because
of that, see __io_cq_lock().
Nicely spotted! Looks good to me.
Apparently I'm wrong as "defer" in that function is not about
defer taskrun, but rather IO_URING_F_COMPLETE_DEFER. Jens, can
you drop it for now?
One way forward would be to limit the aux fast path to defer
taskrun, I don't really care about other cases, and aux is
mostly useful for multishots hence net, which should preferably
be DEFER_TASKRUN.
In any case the code is a bit unhandy if not smelly, can use
some refactoring.
--
Pavel Begunkov
