Messages in this thread |  | | | Date | Wed, 9 Jan 2002 22:06:44 -0800 (PST) | | From | Davide Libenzi <> | | Subject | Re: [PATCH] minor sched-E1 tweaks and questions |
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On Thu, 10 Jan 2002, Rusty Russell wrote:
> Another question: > > if (likely(prev != next)) { > rq->nr_switches++; > rq->curr = next; > next->cpu = prev->cpu; > context_switch(prev, next); > /* > * The runqueue pointer might be from another CPU > * if the new task was last running on a different > * CPU - thus re-load it. > */ > barrier(); > rq = this_rq(); > } > spin_unlock_irq(&rq->lock); > > I do not understand this comment. How can rq (ie. smp_processor_id()) > change? Nothing sleeps here, and if it DID change, the > spin_unlock_irq() would be wrong...
If you switch you'll on the stack the rq of the previous cpu spin_unlock_irq(&rq->lock) is fine if you do not switch and if you switch you need to reload rq
- Davide
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