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

Len Brown
2015-05-14T07:18:45Z

On Thu, May 14, 2015 at 2:36 AM, Len Brown <lenb@kernel.org> 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