Re: [PATCH] x86: skip delays during SMP initialization similar to Xen

[Len Brown]

On Thu, May 14, 2015 at 2:36 AM, Len Brown <lenb@xxxxxxxxxx> wrote:

>> [    2.737884] x86: Booted up 4 nodes, 120 CPUs

> For the record, the same (bare metal) box running latest tip boots
> 10ms/processor quicker

> [    1.553658] x86: Booted up 4 nodes, 120 CPUs

> BTW. this time can be reduced by 7% (113 ms) by deleting announce_cpu():
>
> [    1.445815] x86: Booted up 4 nodes, 120 CPUs

I see that the x2apic optimization has been reverted from TIP.
So just for grins, I booted the same box with all the udelays in
smpboot.c removed,
and it speed up boot by only 12ms (0.8%) total:

[    1.432946] x86: Booted up 4 nodes, 120 CPUs

cheers,
-Len Brown, Intel Open Source Technology Center
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