Messages in this thread | | | Date | Thu, 19 Nov 2009 14:16:34 +0000 | From | Matthew Garrett <> | Subject | Re: [PATCH] [RFC] Add support for uevents on block device idle changes |
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On Thu, Nov 19, 2009 at 02:29:29PM +0100, Kay Sievers wrote: > On Thu, Nov 19, 2009 at 14:01, Matthew Garrett <mjg@redhat.com> wrote: > > On Thu, Nov 19, 2009 at 12:09:30PM +0100, Kay Sievers wrote: > >> On Wed, Nov 18, 2009 at 22:33, Matthew Garrett <mjg59@srcf.ucam.org> wrote: > >> > My use cases are on the order of a second. > >> > >> Ok, what's the specific use case, which should be triggered after a > >> second? I thought you were thinking about disk spindown or similar. > > > > The first is altering ALPM policy. ALPM will be initiated by the host if > > the number of queued requests hits zero - if there's no hysteresis > > implemented, then that can result in a significant performance hit. We > > don't need /much/ hysteresis, but it's the difference between a 50% > > performance hit and not having that. > > Can't that logic live entirely in the kernel, instead of being a > rather generic userspace event interface (with the current limitation > to a single user)?
It could, but it seems a bit of a hack. It'd still also require the timer to be in the kernel, so we might as well expose that to userspace.
-- Matthew Garrett | mjg59@srcf.ucam.org
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