Hi Robert,

On Mon, Jan 09, 2017 at 12:53:20PM +0100, Robert Richter wrote:

On 06.01.17 08:37:25, Ard Biesheuvel wrote:

quoted

Any comments on the performance impact (including boot time) ?

I did a kernel compile test and kernel mode time increases by about
2.2%. Though this is already significant, we need a more suitable mem
benchmark here for further testing.

Thanks for doing this.

For boot time I dont see significant changes.

-Robert


Boot times:

pfn_valid_within():
[   25.929134]
[   25.548830]
[   25.503225]

early_pfn_valid() v3:
[   25.773814]
[   25.548428]
[   25.765290]


Kernel compile times (3 runs each):

pfn_valid_within():

real    6m4.088s
user    372m57.607s
sys     16m55.158s

real    6m1.532s
user    372m48.453s
sys     16m50.370s

real    6m4.061s
user    373m18.753s
sys     16m57.027s

Did you reboot the machine between each build here, or only when changing
kernel? If the latter, do you see variations in kernel build time by simply
rebooting the same Image?

Will