On Tue, 18 Feb 2025 08:45:55 -0800 Kevin Krakauer wrote:
> GRO tests are timing dependent and can easily flake. This is partially
> mitigated in gro.sh by giving each subtest 3 chances to pass. However,
> this still flakes on some machines.
To be clear - are you running this over veth or a real device?
> Set the device's napi_defer_hard_irqs to 50 so that GRO is less likely
> to immediately flush. This already happened in setup_loopback.sh, but
> wasn't added to setup_veth.sh. This accounts for most of the reduction
> in flakiness.
That doesn't make intuitive sense to me. If we already defer flushes
why do we need to also defer IRQs?
> We also increase the number of chances for success from 3 to 6.
>
> `gro.sh -t <test>` now returns a passing/failing exit code as expected.
>
> gro.c:main no longer erroneously claims a test passes when running as a
> server.
>
> Tested: Ran `gro.sh -t large` 100 times with and without this change.
> Passed 100/100 with and 64/100 without. Ran inside strace to increase
> flakiness.
>
> Signed-off-by: Kevin Krakauer <krakauer@xxxxxxxxxx>
> ---
> tools/testing/selftests/net/gro.c | 8 +++++---
> tools/testing/selftests/net/gro.sh | 5 +++--
> tools/testing/selftests/net/setup_veth.sh | 1 +
> 3 files changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/tools/testing/selftests/net/gro.c b/tools/testing/selftests/net/gro.c
> index b2184847e388..d5824eadea10 100644
> --- a/tools/testing/selftests/net/gro.c
> +++ b/tools/testing/selftests/net/gro.c
> @@ -1318,11 +1318,13 @@ int main(int argc, char **argv)
> read_MAC(src_mac, smac);
> read_MAC(dst_mac, dmac);
>
> - if (tx_socket)
> + if (tx_socket) {
> gro_sender();
> - else
> + } else {
> + /* Only the receiver exit status determines test success. */
> gro_receiver();
> + fprintf(stderr, "Gro::%s test passed.\n", testname);
> + }
>
> - fprintf(stderr, "Gro::%s test passed.\n", testname);
That seems quite separate to the stability fix?
> return 0;
> }
> diff --git a/tools/testing/selftests/net/gro.sh b/tools/testing/selftests/net/gro.sh
> index 02c21ff4ca81..703173f8c8a9 100755
> --- a/tools/testing/selftests/net/gro.sh
> +++ b/tools/testing/selftests/net/gro.sh
> @@ -21,7 +21,7 @@ run_test() {
> # Each test is run 3 times to deflake, because given the receive timing,
> # not all packets that should coalesce will be considered in the same flow
> # on every try.
> - for tries in {1..3}; do
> + for tries in {1..6}; do
> # Actual test starts here
> ip netns exec $server_ns ./gro "${ARGS[@]}" "--rx" "--iface" "server" \
> 1>>log.txt &
> @@ -100,5 +100,6 @@ trap cleanup EXIT
> if [[ "${test}" == "all" ]]; then
> run_all_tests
> else
> - run_test "${proto}" "${test}"
> + exit_code=$(run_test "${proto}" "${test}")
> + exit $exit_code
Also separate from stability?
Let's split the patch up into logically separate changes.
> fi;
> diff --git a/tools/testing/selftests/net/setup_veth.sh b/tools/testing/selftests/net/setup_veth.sh
> index 1f78a87f6f37..9882ad730c24 100644
> --- a/tools/testing/selftests/net/setup_veth.sh
> +++ b/tools/testing/selftests/net/setup_veth.sh
> @@ -12,6 +12,7 @@ setup_veth_ns() {
>
> [[ -e /var/run/netns/"${ns_name}" ]] || ip netns add "${ns_name}"
> echo 1000000 > "/sys/class/net/${ns_dev}/gro_flush_timeout"
> + echo 50 > "/sys/class/net/${ns_dev}/napi_defer_hard_irqs"
> ip link set dev "${ns_dev}" netns "${ns_name}" mtu 65535
> ip -netns "${ns_name}" link set dev "${ns_dev}" up
>
--
pw-bot: cr
