Messages in this thread | | | Date | Sat, 23 Jun 2007 00:15:29 +0200 | From | Ingo Molnar <> | Subject | Re: [RFC PATCH 0/6] Convert all tasklets to workqueues |
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* Daniel Walker <dwalker@mvista.com> wrote:
> > - tasklets have certain fairness limitations. (they are executed in > > softirq context and thus preempt everything, even if there is > > some potentially more important, high-priority task waiting to be > > executed.) > > Since -rt has been executing tasklets in process context for a long > time, I'm not sure this change would cause to many regressions. > However, it seems like implicit dependencies on "tasklets preempt > everything" might crop up. The other issue is if they don't "preempt > everything" (most of the time), what default priority do we give them > (all of the time)? [...]
there is no such guarantee at all (of 'instant preemption'), even with current, softirq-based tasklets. A tasklet might be 'stolen' by another CPU. It might be delayed to the next timer tick (or other softirq execution). Or it might be delayed into a ksoftirqd context, which currently runs at nice +19. So your worry of implicit execution dependencies is unfounded, because, if they existed, they would be bad (and triggerable) bugs today too.
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