[netperf-talk] Reported CPU Utilization

[Andrew Gallatin]

On 01/31/11 12:55, Peter F. Klemperer wrote:
> Hi All,
>
> I've seen some interesting results for CPU utilization when running
> netperf that I can't explain. For message size 1 I see a high CPU
> utilization and then a sharp dropoff with increased message size that
> then increases (see attached graph). I did not expect to see that
> initial peak and drop. Can anyone help me understand this?


I'm much more knowledgeable in  *nix than windows, but in general,
small message sizes are going to have a much higher cost per byte
than large message sizes.  This is because of fixed, per-message
costs to do things like perform a system call, lock the socket
buffer for a connection, copy data from userspace to kernel's socket
buffer, etc.

I'm not sure what profiling options you have with windows
in a VM, but I encourage you to profile the different
scenarios if you can.

Drew