[dpdk-dev] NUMA CPU Sockets and DPDK

[Etai Lev Ran]

Hi Prashant,

Based on our experience, using DPDK cross CPU sockets may indeed result in
some performance degradation (~10% for our application vs. staying 
in socket. YMMV based on HW, application structure, etc.).

Regarding CPU utilization on core 1, the one picking up traffic: perhaps I
had misunderstood your comment, but I would expect it to always be close 
to 100% since it's  polling the device via the PMD and not driven by
interrupts. 

Regards,
Etai

-----Original Message-----
From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Prashant Upadhyaya
Sent: Wednesday, February 12, 2014 1:28 PM
To: dev at dpdk.org
Subject: [dpdk-dev] NUMA CPU Sockets and DPDK

Hi guys,

What has been your experience of using DPDK based app's in NUMA mode with
multiple sockets where some cores are present on one socket and other cores
on some other socket.

I am migrating my application from one intel machine with 8 cores, all in
one socket to a 32 core machine where 16 cores are in one socket and 16
other cores in the second socket.
My core 0 does all initialization for mbuf's, nic ports, queues etc. and
uses SOCKET_ID_ANY for socket related parameters.

The usecase works, but I think I am running into performance issues on the
32 core machine.
The lscpu output on my 32 core machine shows the following - NUMA node0
CPU(s): 0,2,4,6,8,10,12,14,16,18,20,22,24,26,28,30
NUMA node1 CPU(s): 1,3,5,7,9,11,13,15,17,19,21,23,25,27,29,31
I am using core 1 to lift all the data from a single queue of an 82599EB
port and I see that the cpu utilization for this core 1 is way too high even
for lifting traffic of 1 Gbps with packet size of 650 bytes.

In general, does one need to be careful in working with multiple sockets and
so forth, any comments would be helpful.

Regards
-Prashant





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