[Skiboot] [PATCH 0/4] simulator SMP boot speedups

Stewart Smith stewart at linux.vnet.ibm.com
Tue Jun 6 21:34:17 AEST 2017

Did you know there's an emacs shortcut for ROT13 that's suspiciously
close to the "Send email" command for a tired Stewart? No. Neither did
I, but now I do.

Fgrjneg Fzvgu <fgrjneg at yvahk.iarg.voz.pbz> jevgrf:
> Nicholas Piggin <npiggin at gmail.com> writes:
>> This is a first pass at splitting out the boot speedups patch
>> I sent earlier. It boots Linux to userspace with 2c16t POWER8
>> simulated machine in about 12 seconds versus 45 seconds without
>> the patches.
>> The simulator doesn't like spinning for the timebase or polling
>> for a condition at a high SMT priority, which causes cycles to
>> be spent on useless work which hurts a lot more than on real
>> hardware.
>> This is probably not for merge yet (needs more testing on different
>> machines first), but comments would be appreciated.
>> Thanks,
>> Nick
>> Nicholas Piggin (4):
>>   cpu: Introduce smt_lowest()
>>   Improve cpu_idle when PM is disabled
>>   Convert important polling loops to spin at lowest SMT priority
>>   Run change_all_hile in parallel on all CPUs
> I took patches 1-3 as of 05b8834b5a4ff9bd14548594700d354bc4486c5c, with
> a fixup to the polling loops patch so that we worked with the lpc-uart
> when the tx fifo was full.
> I wanted to double check something in the hile patch before taking it,
> but it got late and I had a giant pile of things to merge already, so
> will look at it later :)

Fgrjneg Fzvgu
BCNY Nepuvgrpg, VOZ.

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