[netperf-talk] global question concerning Netperf test and SMP support

[Rick Jones]

I'm a bit surprised that 128 byte send sizes is faster than 16K, but I 
suppose if the system is small enough, or has a small enough page size 
(?) there may be some issues with ease of buffer allocation.

I might have guessed something to do with processor data cache 
residency, but presumably the size of the send ring will be, by default, 
one more buffer than fits in the SO_SNDBUF size when the data socket is 
created - I suppose if the cache is < 32KB the 128 B send case would 
have the buffer ring fit and 16KB sends would not.  Testing that would 
call for HW counter information from the processor.  Going back through 
the string you mentioned something with 32KB L1 data cache and a 128 KB 
L2 cache - is that on both sides or just one?

Some experimentation with different socket buffer sizes, explicitly set 
with test-specific -s and -S might be a good thing.

That the remote CPU utilization is coming back as a negative value is 
quite troubling and requires further investigation.

I wouldn't expect redirecting netperf output to cause a big performance 
change, certainly not one that would vary with the parms to netperf - 
the quantity of output will be the same whether -m is 128 or 16K or 
anything else.

happy benchmarking,

rick jones