Re: rps testing questions

On Mon, 2011-01-17 at 17:43 +0800, mi wake wrote:

I do a rps(Receive Packet Steering) testing on centos 5.5 with  kernel 2.6.37.
cpu: 8 core Intel.
ethernet adapter: bnx2x

Problem statement:
enable rps with:
echo "ff" > /sys/class/net/eth2/queues/rx-0/rps_cpus.

running 1 instances of netperf TCP_RR: netperf  -t TCP_RR -H 192.168.0.1 -c -C
without rps: 9963.48(Trans Rate per sec)
with rps:  9387.59(Trans Rate per sec)

I do ab and tbench testing also find there is less tps with enable
rps.but,there is more cpu using when with enable rps.when with enable
rps ，softirqs is blanced  on cpus.

is there something wrong with my test？

In addition to what Eric said, check the interrupt moderation settings
(ethtool -c/-C options).  One-way latency for a single request/response
test will be at least the interrupt moderation value.

I haven't tested RPS by itself (Solarflare NICs have plenty of hardware
queues) so I don't know whether it can improve latency.  However, RFS
certainly does when there are many flows.

Ben.

-- 
Ben Hutchings, Senior Software Engineer, Solarflare Communications
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.