Messages in this thread | | | From | Andy Lutomirski <> | Date | Wed, 21 May 2014 15:32:33 -0700 | Subject | Re: [RFC] x86_64: A real proposal for iret-less return to kernel |
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On Wed, May 21, 2014 at 3:25 PM, Andi Kleen <andi@firstfloor.org> wrote: > > Seems like a lot of effort and risk to essentially only optimize in kernel > interrupt handlers.
The idea is that it might allow us to remove a bunch of scary nested NMI code as well as speeding things up.
> > AFAIK the most interesting cases (like user page faults) are not > affected at all. Usually most workloads don't spend all that much time > in the kernel, so it won't help most interrupts. > > I suspect the only case that's really interesting here is interrupting > idle. Maybe it would be possible to do some fast path in this case only. > > However idle currently has so much overhead that I suspect that there > are lower hanging fruit elsewhere.
I will gladly buy a meal or beverage for whomever fixes the ttwu stuff to stop sending IPIs to idle CPUs, which will help a lot.
--Andy
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