Messages in this thread | | | Date | Tue, 21 Mar 2000 08:58:59 -0700 | From | yodaiken@fsmlabs ... | Subject | Re: scheduler ignores need_resched flag in 2.2.x and 2.3.x? |
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On Tue, Mar 21, 2000 at 12:33:25PM +0000, Alan Cox wrote: > > This is what makes Ingo's latency patch less dangerous: need_resched is hard > > to set. Your scenario requires that an interrupt routine, interrupting > > kernel mode, set needs_resched. Where does this happen? > > A process wake from interrupt state - eg a network event. Its not actually > that uncommon. The window is small however so it isnt likely to get hit > much.
The scheduler is too complex for me. So the confusingly named "reschedule_idle" is called on wake and if preemption_goodness tells it to, it can set need_resched, which as Jun Sun, points out, can belong to a process that is in the middle of being replaced by a second process. Ok. That makes sense and his fix seems reasonable: need current->needs_resched = (prev->needs_resched?1:current->needs_resched); in __schedule_tail
Thanks.
BTW: the comments on schedule, that it is simple and nice and that "the goto" is interesting are out of date.
-- --------------------------------------------------------- Victor Yodaiken FSMLabs: www.fsmlabs.com www.rtlinux.com FSMLabs is a servicemark and a service of VJY Associates L.L.C, New Mexico.
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