ACK: [PATCH 1/1] selftests/net: relax cpu affinity requirement in msg_zerocopy test

[Thadeu Lima de Souza Cascardo]

On Thu, Aug 06, 2020 at 10:59:44AM +0100, Colin King wrote:
> From: Willem de Bruijn <willemb at google.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/1812620
> 
> The msg_zerocopy test pins the sender and receiver threads to separate
> cores to reduce variance between runs.
> 
> But it hardcodes the cores and skips core 0, so it fails on machines
> with the selected cores offline, or simply fewer cores.
> 
> The test mainly gives code coverage in automated runs. The throughput
> of zerocopy ('-z') and non-zerocopy runs is logged for manual
> inspection.
> 
> Continue even when sched_setaffinity fails. Just log to warn anyone
> interpreting the data.
> 
> Fixes: 07b65c5b31ce ("test: add msg_zerocopy test")
> Reported-by: Colin Ian King <colin.king at canonical.com>
> Signed-off-by: Willem de Bruijn <willemb at google.com>
> Acked-by: Colin Ian King <colin.king at canonical.com>
> Signed-off-by: David S. Miller <davem at davemloft.net>
> (cherry picked from commit 16f6458f2478b55e2b628797bc81a4455045c74e linux-next)
> Signed-off-by: Colin Ian King <colin.king at canonical.com>
> ---
>  tools/testing/selftests/net/msg_zerocopy.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/testing/selftests/net/msg_zerocopy.c b/tools/testing/selftests/net/msg_zerocopy.c
> index 4b02933cab8a..bdc03a2097e8 100644
> --- a/tools/testing/selftests/net/msg_zerocopy.c
> +++ b/tools/testing/selftests/net/msg_zerocopy.c
> @@ -125,9 +125,8 @@ static int do_setcpu(int cpu)
>  	CPU_ZERO(&mask);
>  	CPU_SET(cpu, &mask);
>  	if (sched_setaffinity(0, sizeof(mask), &mask))
> -		error(1, 0, "setaffinity %d", cpu);
> -
> -	if (cfg_verbose)
> +		fprintf(stderr, "cpu: unable to pin, may increase variance.\n");
> +	else if (cfg_verbose)
>  		fprintf(stderr, "cpu: %u\n", cpu);
>  
>  	return 0;
> -- 
> 2.27.0

Thanks!

Acked-by: Thadeu Lima de Souza Cascardo <cascardo at canonical.com>