When chasing a performance issue on ppc64, I noticed tasks
communicating via a pipe would often end up on different nodes.
It turns out SD_WAKE_AFFINE is not set in our node defition. Commit
9fcd18c9e6 (sched: re-tune balancing) enabled SD_WAKE_AFFINE
in the node definition for x86 and we need a similar change for
ppc64.
I used lmbench lat_ctx and perf bench pipe to verify this fix. Each
benchmark was run 10 times and the average taken.
lmbench lat_ctx:
before: 66565 ops/sec
after: 204700 ops/sec
3.1x faster
perf bench pipe:
before: 5.6570 usecs
after: 1.3470 usecs
4.2x faster
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
a200d8e446