Messages in this thread | | | From | Daniel Phillips <> | Subject | Re: [2.4.17/18pre] VM and swap - it's really unusable | Date | Wed, 9 Jan 2002 07:36:16 +0100 |
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On January 9, 2002 12:26 am, Luigi Genoni wrote: > On Tue, 8 Jan 2002, Daniel Phillips wrote: > > > On January 8, 2002 08:47 pm, Andrew Morton wrote: > > > Daniel Phillips wrote: > > > > What a preemptible kernel can do that a non-preemptible kernel can't is: > > > > reschedule exactly as often as necessary, instead of having lots of extra > > > > schedule points inserted all over the place, firing when *they* think the > > > > time is right, which may well be earlier than necessary. > > > > > > Nope. `if (current->need_resched)' -> the time is right (beyond right, > > > actually). > > > > Oops, sorry, right. > > > > The preemptible kernel can reschedule, on average, sooner than the > > scheduling-point kernel, which has to wait for a scheduling point to roll > > around. > > mmhhh. At which cost? And then anyway if I have a spinlock, I still have > to wait for a scheduling point to roll around.
Did you read the thread? Think about the relative amount of time spent in spinlocks vs the amount of time spent in the regular kernel.
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