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

Len Brown
2015-05-16T08:46:24Z

On Thu, May 14, 2015 at 2:44 AM, Ingo Molnar <mingo@kernel.org> wrote:

>
>> BTW. this time can be reduced by 7% (113 ms) by deleting
>> announce_cpu():
>>
>> [ 1.445815] x86: Booted up 4 nodes, 120 CPUs
>
> so that kind of info looks pretty useful, especially when there's
> hangs/failures.

I think the messages we print on failure are useful.
I think the success case should be a 1-line summary.

> I'm wondering what takes 113 msecs to print 120 CPUs -
> that's about 1 msec per a few chars of printk produced, seems
> excessive. Do you have any idea what's going on there? Does your
> system print to a serial console perhaps?

Yes, serial console -- that server is actually much
closer to you than it is to me, it is in Finland:-)

I should benchmark it, because 115200 should be faster...

cheers,
Len Brown, Intel Open Source Technology Center