big bw_pipe drop due to sched-domain patch?

[David Mosberger]

Today I noticed that going from 2.6.6 to 2.6.7-rc1 caused a big drop
in LMbench2 bw_pipe throughput on a dual-CPU machine (2.6.7-rc1 shows
10 times lower bandwidth than 2.6.6).  It appears that the drop is due
to the two tasks being distributed across the two CPUs, rather than
being kept on the same CPU.  If I force the tasks to be pinned on a
single CPU, e.g., like so:

	$ taskset 1 ./bw_pipe

then performance is "only" about 10% worse than with 2.6.6.

Is this kind of drop expected?

	--david
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