Messages in this thread | | | Subject | Re: [RFC] schedule_timeout_range() | From | David Woodhouse <> | Date | Tue, 22 Jul 2008 00:45:25 -0400 |
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On Tue, 2008-07-22 at 14:33 +1000, Nick Piggin wrote: > The only thing I dislike about explicit times is that when a driver or > someone doesn't _really_ know how much to specify. Do you say 10s, 100s?
This is true, but they certainly have a _better_ idea than we do. If the individual callers can't even come up with an answer, how are we ever going to come up with a generic policy that does the right thing?
I really don't think that applying this kind of policy in generic code is useful -- I'd like the callers to provide numbers even if they _do_ pull it out of their wossname.
The number they provide is the _maximum_ amount of time they should be prepared to wait (let's assume for a moment that they stayed sober and remembered Linux isn't a real-time kernel, so all guarantees are taken with a pinch of salt. Let's not get bogged down in nomenclature).
In practice, they'll almost always get called before that maximum time expires -- that's the whole _point_, of course. But we can't _invent_ that maximum in generic code; that's really up to the caller.
> Some upper bound would be nice, which basically would not have to ever > fire by itself unless there is some CPU activity (so you don't have to > set two timers as a bonus). After that, I wonder, perhaps some "maximum > power savings value but not completely deferred"? Say give it a max of > 30s? Or perhaps even that is not future-proof enough if we one day want > to suspend most of the system between external IOs?
I _really_ don't think we want to go there. Let the caller set a maximum amount of time they're prepared to wait, and that's it.
-- dwmw2
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