[PATCH 0/1][SRU][Focal][Groovy] selftests/net: relax cpu affinity requirement in msg_zerocopy test

[Po-Hsu Lin]

Hello folks,

I just found that this issue is affecting the B/hwe 5.3 as well.
Can we add this patch the B/hwe too?
(It's also a cherry-pick, and I have the bug nominated for linux-hwe)

Thanks
Sam

On Thu, Aug 6, 2020 at 6:00 PM Colin King <colin.king at canonical.com> wrote:
>
> From: Colin Ian King <colin.king at canonical.com>
>
> BugLink: https://bugs.launchpad.net/bugs/1812620
>
> == SRU Justification [ FOCAL ] ==
>
> The msg_zerocopy.sh kernel self test will fail on machines that don't
> have 2 or 3 CPUs such as 1 CPU cloud instances since the C test program
> tries to set CPU affinity to CPUs 2 and 3 and bails out if it fails.
>
> == Fix ==
>
> Upstream linux-next commit
>
> commit 16f6458f2478b55e2b628797bc81a4455045c74e
> Author: Willem de Bruijn <willemb at google.com>
> Date: Wed Aug 5 04:40:45 2020 -0400
>
>     selftests/net: relax cpu affinity requirement in msg_zerocopy test
>
> The fix now just emits a warning that CPU affinity can't be set
> rather than cause an exit(1) termination.
>
> == Test cast ==
>
> Run the msg_zerocopy.sh test from the kernel net selftest on a 1 CPU
> system or a system with CPUs 2-3 offline'd. Without the fix the test
> fails. With the fix it runs successfully as expected.
>
> == Regression Potential ==
>
> The original test pinned the CPUs for a benchmarking metric, for our
> testing we are using this to test to see if the operations in the tes
>  work successfully. There is a potential that users using this test
> will not notice the warning if they are using this test as a benchmark
> on a 1 CPU system and may get more jittery timing in their benchmarks
> rather than a test failing and complaining they are not running it on
> a suitable multi-CPU system. However, the likelyhood of a user using
> this test on a single CPU system for benchmarking is small and as it
> stands the test will now run and produce potentially jittery benchmarks
> on a 1 CPU system compared to previously where it never ran.
>
> Willem de Bruijn (1):
>   selftests/net: relax cpu affinity requirement in msg_zerocopy test
>
>  tools/testing/selftests/net/msg_zerocopy.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
>
> --
> 2.27.0
>
>
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