On Thu, Oct 23, 2014 at 11:45:05AM -0700, Roland Dreier wrote: > On Thu, Oct 23, 2014 at 10:21 AM, Evgenii Smirnov > <evgenii.smirnov@xxxxxxxxxxxxxxxx> 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. > I assume ib_send_bw uses inline with blueflame so it may be part of the explanation to the differences you see. -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
