From owner-freebsd-stable@FreeBSD.ORG  Sat Dec 17 21:20:46 2011
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From: Adrian Chadd <adrian@freebsd.org>
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Cc: George Mitchell <george+freebsd@m5p.com>, freebsd-stable@freebsd.org,
	Oliver Pinter <oliver.pntr@gmail.com>
Subject: Re: SCHED_ULE should not be the default
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Erm, just as a random question - since device drivers (and GEOM) run
as separate threads, has anyone looked into what kind of effects the
scheduler has on these?

I definitely have measurable throughput/responsiveness differences
between ULE and 4BSD (and preempt/non-preempt on 4BSD) on my MIPS
boards when they're bridging traffic. I wonder if there's something
strange going on with the scheduling and preemption of driver netisrs,
taskqueues, the fast interrupt handlers, etc.

This may -not- be a userland specific problem..


Adrian