Re: [RFC] maximum latency tracking infrastructure

[Nick Piggin]

Arjan van de Ven wrote:
> Nick Piggin wrote:

> > Surely you would call set_acceptable_latency() *before* running such
> > operation that requires the given latency? And that 
> > set_acceptable_latency
> > would block the caller until all CPUs are set to wake within this 
> > latency.
> >
> > That would be the API semantics I would expect, anyway.
>
>
> but that means it blocks, and thus can't be used in irq context

Is that a problem? I guess it could be, but you don't want to
give a false sense of security either. Having an explicit _nosync
version may make that clear?

> (the usage model I imagine happens most is a set_acceptable_latency() 
> which can block during device init,
> with either no or a very course limit, and a 
> modify_acceptable_latency(), which cannot block, from irq context or
> device open)

OK. You'd know more about that than I ;)

--
SUSE Labs, Novell Inc.
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