[dpdk-dev] KNI Out of memory

Ivano Cerrato 8002onavi at gmail.com
Wed Aug 27 10:40:48 CEST 2014

I wrote a code that creates some KNI interfaces, destroys them when some 
management events occur, and creates new interfaces when other 
management events happen.
What happens is that I create a number of interfaces using "kni_alloc", 
I destroy ALL of them through "kni_release" and, when I try to create a 
new one I get the message "KNI out of memory" during the execution of 
the "kni_alloc".

The number of interfaces that I can create/destroy before getting the 
error depends on the size of the mempool that I specify during the 
creation of the interfaces themselves.
Then, to me it seems that the memory is not properly released when a KNI 
interface is destroyed. Before invoking "kni_release", I drain all the 
remaining mbufs in the tx queues. While checking the sources of DPDK, I 
have seen that indeed this trace only appears when there there are no 
mbufs available in the mempool.

Am I missing something here?  Is there any other call necessary to 
properly release a KNI interface?

Just before/after the creation and release of an interface, I print the 
values obtained by invoking "rte_mempool_count" and 
"rte_mempool_free_count" on the mempool used for the KNI. What I get is 
the following: the value obtained with "rte_mempool_count" tends to 
decrease, while the value get with "rte_mempool_free_count" tends to 

What is the exact semantic of "rte_mempool_count" and 
"rte_mempool_free_count"? From the doxygen documentation, it seems that 
the behaviour should be the opposite.

Best regards,


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