Messages in this thread | | | Date | Sat, 12 Jan 2002 21:53:41 +0100 | From | Roman Zippel <> | Subject | Re: [2.4.17/18pre] VM and swap - it's really unusable |
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Hi,
Alan Cox wrote:
> So with pre-empt this happens > > driver magic > disable_irq(dev->irq) > PRE-EMPT: > [large periods of time running other code] > PRE-EMPT: > We get back and we've missed 300 packets, the serial port sharing > the IRQ has dropped our internet connection completely.
But it shouldn't deadlock as Victor is suggesting.
> There are numerous other examples in the kernel tree where the current code > knows that there is a small bounded time between two actions in kernel space > that do not have a sleep. They are not spin locked, and putting spin locks > everywhere will just trash performance. They are pure hardware interactions > so you can't automatically detect them.
Why should spin locks trash perfomance, while an expensive disable_irq() doesn't?
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