On Thu, Oct 23, 2014 at 10:21 AM, Evgenii Smirnov
<evgenii.smir...@profitbricks.com> wrote:
> I am trying to achieve high packet per second throughput with 2-byte
> messages over Infiniband from kernel using IB_SEND verb. The most I
> can get so far is 3.5 Mpps. However, ib_send_bw utility from perftest
> package is able to send 2-byte packets with rate of 9 Mpps.
> After some profiling I found that execution of ib_post_send function
> in kernel takes about 213 ns in average, for the user-space function
> ibv_post_send takes only about 57 ns.
> As I understand, these functions do almost same operations. The work
> request fields and queue pair parameters are also the same. Why do
> they have such big difference in execution times?


Interesting.  I guess it would be useful to look at perf top / and or
get a perf report with "perf report -a -g" when running your high PPS
workload, and see where the time is wasted.

 - R.
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