Subject: Re: [PATCH v3 0/6] powerpc use pv-qpsinlock as the default spinlock implemention

From: Peter Zijlstra <[email-masked]>
Date: Thu, 26 May 2016 18:54:23 +0200

On Wed, May 25, 2016 at 04:18:03PM +0800, Pan Xinhui wrote:
> I do several tests on pseries IBM,8408-E8E with 32cpus, 64GB memory.
> benchmark test results are below.

> _____test________________spinlcok______________pv-qspinlcok_____
> | compiling takes|	22m 		|	22m		|

How can a kernel build take 22 minutes with 32 CPUs? That's far too
long. My 40 CPU IVB-EP takes all of 50 seconds to build an
x86_64-defconfig from scratch.