Re: [PATCH] selftests/kvm: Fix bug in how demand_paging_test calculates paging rate

[Oliver Upton <oliver.upton@linux.dev>]

The shortlog doesn't give any hint as to what the bug actually is.
Maybe:

  KVM: selftests: Fix nsec to sec conversion in demand_paging_test

On Thu, Feb 16, 2023 at 08:02:18PM +0000, Anish Moorthy wrote:
> The current denominator is 1E8, not 1E9 as it should be.

  demand_paging_test uses 1E8 as the denominator to convert nanoseconds
  to seconds, which is wrong. Use NSEC_PER_SEC instead to fix the issue
  and make the conversion obvious.

> Reported-by: James Houghton <jthoughton@google.com>
> Signed-off-by: Anish Moorthy <amoorthy@google.com>

Bikeshedding aside:

Reviewed-by: Oliver Upton <oliver.upton@linux.dev>

> ---
>  tools/testing/selftests/kvm/demand_paging_test.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
> index b0e1fc4de9e29..2439c4043fed6 100644
> --- a/tools/testing/selftests/kvm/demand_paging_test.c
> +++ b/tools/testing/selftests/kvm/demand_paging_test.c
> @@ -194,7 +194,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
>  		ts_diff.tv_sec, ts_diff.tv_nsec);
>  	pr_info("Overall demand paging rate: %f pgs/sec\n",
>  		memstress_args.vcpu_args[0].pages * nr_vcpus /
> -		((double)ts_diff.tv_sec + (double)ts_diff.tv_nsec / 100000000.0));
> +		((double)ts_diff.tv_sec + (double)ts_diff.tv_nsec / NSEC_PER_SEC));
>  
>  	memstress_destroy_vm(vm);
>  
> -- 
> 2.39.2.637.g21b0678d19-goog
> 

-- 
Thanks,
Oliver