Messages in this thread | | | Date | Tue, 5 Jun 2012 23:15:16 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [PATCH 0/6] x86/cpu hotplug: Wake up offline CPU via mwait or nmi |
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On Tue, 5 Jun 2012, Andi Kleen wrote: > Thomas Gleixner <tglx@linutronix.de> writes: > > > > Vs. the interrupt/timer/other crap madness: > > > > - We really don't want to have an interrupt balancer in the kernel > > again, but we need a mechanism to prevent the user space balancer > > trainwreck from ruining the power saving party. > > Why not? I think the kernel is exactly the right place for it. > It's essentially a scheduling problem. Scheduling in user space > is not a good idea.
No argument about scheduling in user space. Though the real problem is where do you draw the line between mechanism and policy?
> With MSI-X the drivers just want a static setting. User space > shouldn't mess with it. > > Some of the workarounds for user space messing with it (like that > interrupt rmap code) are really bad and just a workaround for doing the > scheduling in the wrong place. > > For dynamic changes it should indeed by part of scheduling, > following similar rules, with only high level policy input > from userland.
I'd be happy to see a patch which implements all of that and avoids the pitfalls of the old in kernel irq balancer along with the short comings of the user space one.
Thanks,
tglx
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