Messages in this thread | | | Date | Sat, 20 Nov 2004 12:50:57 +0100 | From | Florian Schmidt <> | Subject | Re: [patch] Real-Time Preemption, -RT-2.6.10-rc2-mm2-V0.7.29-0 |
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On Fri, 19 Nov 2004 22:22:42 -0500 Lee Revell <rlrevell@joe-job.com> wrote:
> On Thu, 2004-11-18 at 17:46 +0100, Ingo Molnar wrote: > > i have released the -V0.7.29-0 Real-Time Preemption patch, which can be > > downloaded from the usual place: > > > > http://redhat.com/~mingo/realtime-preempt/ > > I tried this with CONFIG_PREEMPT_VOLUNTARY (which should theoretically > work like the earlier VP patches, right?) to test for regressions. The > boot process hung after initializing my IDE controller.
I thought so, too, until ingo set me straight (quote ingo):
here are the different layers of preemption:
- !PREEMPT - PREEMPT_VOLUNTARY - PREEMPT - PREEMPT_RT
each step forward decreases latencies, at the cost of more runtime overhead.
so PREEMPT_VOLUNTARY is not "the" feature anymore, it's "a" feature down the hierarchy. In fact the focus is mostly on PREEMPT_RT now.
quote end..
So with RP kernels, PREEMPT is what gives best latency when full realtime preemption is not an option
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