Issues with Patch: "sched: Improve latencies and throughput"

[Michael Grzeschik <mgr@pengutronix.de>]

We are using an arm mx31 embedded cpu with the v2.6.34 Kernelrelease and
realized some issues with the scheduling behaviour the patch "sched:
Improve latencies and throughput" [1] by Mike Galbraith introduced to
the kernel.

When we used the alsa utility aplay to pipe some audio through an
usbaudio device and put some scheduling overhead on the device, the
amount of underruns, due to the not fast enough refilled ring buffer,
was noticable increased with that patch [1] applied. Until we reverse
applied the patch the amount of underruns was appreciable lower.

That in fact is the opposite behaviour to its actual meaning.

[1] 0ec9fab3d186d9cbb00c0f694d4a260d07c198d9

mgr

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