On Jul 13, 2010 06:55 PM, "Hefty, Sean" <sean.he...@intel.com> wrote:
> > I see that this rdma_post_send call gives a big contribute to CPU > > use on > > client side. Now the CPU usage (%) is about 95%-99%. > > CPU utilization is usually related to how you process completions. If > you switch from polling the CQ to using events, the CPU utilization > will go down. This will also result in the latency going up. > > > Could you please send me a comment also about the "plateau non > > stable" > > in graph speed versus buffer size with buffer size > 10^5 bytes? > > (attached files) > > This is likely just an artifact of the test and hardware. Hi Sean, thank you for the clarification about CPU utilization. I understand the smaller is CPU utilization the greater is latency. case A) (my actual test) use CQs --> low latency about as designed | CPU utilization = 99% case B) use events (remove poll in CQs)--> worse latency | low CPU utilization Is it possible a compromise? I think the answer is negative but I'm not an expert. This question is open. For the second point, I have results from 13 speed test. I put in the graph the mean of speed for each buffer size with +- standard deviation as symmetric error barr. It is not a complete statistical analysis but it's an idea. I'm agree with Sean's opinion about the "plateau". Thanks a lot. Regards, Andrea Andrea Gozzelino INFN - Laboratori Nazionali di Legnaro (LNL) Viale dell'Universita' 2 -I-35020 - Legnaro (PD)- ITALIA Office: E-101 Tel: +39 049 8068346 Fax: +39 049 641925 Mail: andrea.gozzel...@lnl.infn.it Cell: +39 3488245552
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