Hi Prashant,
do you pass flags to odp_ring_create that it's multi consumer, multi
producer?
Maxim.
On 08/22/2014 12:12 PM, Prashant Upadhyaya wrote:
Hi,
I have a usecase where each core has a ring associated with it.
Every core dequeues from its own ring – thus each core’s ring above is
representing the single consumer mode.
Every core can enqueue to every other core’s ring – thus each core’s
ring above is representing the multi-producer mode.
To enqueue, I use odp_ring_mp_enqueue_bulk
To dequeue, I use odp_ring_sc_dequeue_bulk
I try to enqueue in a loop till the enqueue succeeds, the idea being
that the other cores will dequeue eventually to create space on the
ring. I use fixed size rings.
Now when I run my usecase, which has a lot of pipelining between
cores, I see that sometimes the code, which is enqueueing on a ring,
blocks in the loop i.e. its enqueue never succeeds.
If I use my own locks to protect the enqueue and dequeue on a given
core’s ring, then my usecase works fine.
Now then, I have not yet been able to get to the bottom of this and
can’t exactly put a finger on where the bug lies in the ring
framework, but the fact that my own external locking vanishes the
problem, I am inclined to believe that there seems to be some race
condition in rings implementation when there are multi producers and a
single consumer.
I am not getting enough time to run some standalone stress tests to
reproduce the above issue in a controlled environment for further
debugging.
If anybody on the list volunteers to test the above or has encountered
a similar problem, we probably have a chance to debug and fix this issue.
Regards
-Prashant
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