Diego Guella wrote:
----- Original Message -----
A newbie question about InfiniBand: while running an RDMA bandwidth
test I noticed that the RDMA communication occupied 99% CPU time,
which is much more than I expected for InfiniBand. Is this normal or
should I check my setup ?
How the test was run:
(host 1) ib_rdma_bw -s 104857600
(host 2) time ib_rdma_bw -s 104857600 192.168.64.7
I think it's normal, I see the same behavior here.
If you take a look at ib_rdma_bw code, you can see that the program
waits in a while() loop, polling the CQ for the WC to appear.
I think it's coded that way to get the WC as soon as possible and
report a more precise time (that is used after to compute BW).
If you don't want that behavior in your application you could use
event notification for the CQ.
If one wants to reduce the CPU usage (on the expense of the latency) he
can work with CQ events.
Dotan
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