On Sat, Aug 22, 2015 at 12:53:15AM +0800, Julian Elischer wrote:
> On 8/22/15 12:23 AM, Ian Lepore wrote:
> > On Fri, 2015-08-21 at 23:30 +0800, Julian Elischer wrote:
> >> On 8/21/15 11:25 PM, Adrian Chadd wrote:
> >>> Ah, cool. I'll give it a whirl.
> >>> I'm a little worried about having all of the other cores spinning in
> >>> this case (mostly thermal; the machines get VERY LOUD when the CPUs
> >>> are spinning..)
> >> make each spin with the pause instruction.. and for N seconds (N being
> >> the CPU ID) or something
> > cpu_spinwait() is defined as ia32_pause() on i386 and amd64.
> > The problem is that ONLY x86 arches benefit from cpu_spinwait(), it's
> > just a nop on other arches, which turn into little radiant heaters for
> > long spins (like while waiting for APs to be released).
> remind me again why it cant spin with a 'halt' instruction?
Because interrupts are disabled. Even NMI is disabled, because spin
happens in the NMI handler. There is no way to wake up CPU from the
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