Re: [PATCH -tip -v5] irq_work: generic hard-irq context callbacks

[Paul Mackerras]

On Fri, Sep 17, 2010 at 03:06:42PM +0200, Peter Zijlstra wrote:

> Provide a mechanism that allows running code in IRQ context. It is most
> useful for NMI code that needs to interact with the rest of the system
> -- like wakeup a task to drain buffers.
> 
> Perf currently has such a mechanism, so extract that and provide it as a
> generic feature, independent of perf so that others may also benefit.
> 
> The IRQ context callback is generated through self-IPIs where possible,
> or on architectures like powerpc which have soft-disabled IRQs, its ran
> on the soft-enable path.

Actually these days we do it by setting the decrementer (the built-in
timer facility) to generate an interrupt immediately (well, within one
timebase tick, i.e. a small number of nanoseconds).

Paul.
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