Re: PREEMPT_RT vs I-PIPE: the numbers, part 2

From: hui
Date: Wed Jun 22 2005 - 15:18:17 EST

On Wed, Jun 22, 2005 at 04:10:57PM -0400, Karim Yaghmour wrote:
> Bill Huey (hui) wrote:
> > FreeBSD went through some slow down when they moved to SMPng, but not
> > the kind of numbers you show for things surrounding the network stack.
> > Something clearly bad happened.
> Note that the numbers are not freak accidents, they are consistent
> accross the various setups. So in total, that's 15 LMbench runs,
> all showing consistent _severe_ cost for preempt_rt. And this despite

Yeah, I looked at the numbers more carefully and it's clearly showing
some problems. There is a significant context switch penalty with
irq-threads and I wouldn't surprise if this is what's going on.


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