cpu affinity and lmbench - ac and mjc

LMbench shows some differences several local communication, local bandwidth, and context switch metrics between 2.4.19-pre10-ac2 and 2.4.19-pre10-mjc1.

The latency/bandwidth differences are similar to 2.4.19-pre10aa2 and 2.4.19-jam2, but bigger.

In trying to isolate the differences in the aa/jam series, it appeared the irqrate/irqbalance in jam2 was the differentiating factor.

mjc1 and ac2 are similar to jam/aa. mjc1 is a patchset to ac2. mjc1 doesn't include irqrate/irqbalance though.

I ran ac2 with 1 cpu enabled on a quad xeon to get a better idea of how processor affinity affects lmbench.

Analysis of mjc1, ac2, and ac2 with 1 cpu is here:

http://home.earthlink.net/~rwhron/kernel/lmbench_affinity.html

comments, suggestions welcome.

Randy Hron
http://home.earthlink.net/~rwhron/kernel/bigbox.html