On Friday 18 January 2008 17:33, stephane eranian wrote: > Nick, > > It is arch specific. If an architecture wants interrupts on during > > context switch, or runqueue unlocked, then they set it (btw > > INTERRUPTS_ON_CTXSW also implies UNLOCKED_CTXSW). > > Yes , I noticed that. I am only interested in UNLOCKED_CTXSW. > But it appears that the approach suggested my Peter does work. We are > running some tests. OK, that might be OK. > > Although, eg on x86, you would hold off interrupts and runqueue lock for > > slightly less time if you defined those, it results in _slightly_ more > > complicated context switching... although I did once find a workload > > where the reduced runqueue contention improved throughput a bit, it is > > not much problem in general to hold the lock. > > By complicated you mean that now you'd have to make sure you don't > need to access runqueue data? Well, not speaking about the arch-specific code (which may involve more complexities), but the core scheduler needs the task_struct->oncpu variable wheras that isn't required if the runqueue is locked while switching tasks. - To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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