selftests/net: relax cpu affinity requirement in msg_zerocopy test

[ Upstream commit 16f6458f2478b55e2b628797bc81a4455045c74e ]

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@canonical.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/tools/testing/selftests/net/msg_zerocopy.c b/tools/testing/selftests/net/msg_zerocopy.c
index e11fe84de0fd92f9123b9bb75c0745123ad43546..6184d2a4c4a62e29a7723d6a9cb6bc7fdc9a38c4 100644 (file)
--- a/tools/testing/selftests/net/msg_zerocopy.c
+++ b/tools/testing/selftests/net/msg_zerocopy.c
@@ -121,9 +121,8 @@ 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;