Re: [PATCH v2 net-next 2/2] selftests: virtio_net: add buffer circulation test

[Vishwanath Seshagiri <vishs@meta.com>]

On 1/28/26 2:12 PM, Michael S. Tsirkin wrote:
> On Wed, Jan 28, 2026 at 01:20:31PM -0800, Vishwanath Seshagiri wrote:
>> Add iperf3-based test to verify RX buffer handling under load.
>> Optionally logs page_pool tracepoints when available.
>>
>> Signed-off-by: Vishwanath Seshagiri <vishs@meta.com>
>> ---
>>   .../drivers/net/virtio_net/basic_features.sh  | 70 +++++++++++++++++++
>>   1 file changed, 70 insertions(+)
>>
>> diff --git a/tools/testing/selftests/drivers/net/virtio_net/basic_features.sh b/tools/testing/selftests/drivers/net/virtio_net/basic_features.sh
>> index cf8cf816ed48..c2c8023d2b92 100755
>> --- a/tools/testing/selftests/drivers/net/virtio_net/basic_features.sh
>> +++ b/tools/testing/selftests/drivers/net/virtio_net/basic_features.sh
>> @@ -6,6 +6,7 @@
>>   ALL_TESTS="
>>   	initial_ping_test
>>   	f_mac_test
>> +	buffer_circulation_test
>>   "
>>   
>>   source virtio_net_common.sh
>> @@ -16,6 +17,8 @@ source "$lib_dir"/../../../net/forwarding/lib.sh
>>   h1=${NETIFS[p1]}
>>   h2=${NETIFS[p2]}
>>   
>> +require_command iperf3
>> +
>>   h1_create()
>>   {
>>   	simple_if_init $h1 $H1_IPV4/24 $H1_IPV6/64
>> @@ -83,6 +86,73 @@ f_mac_test()
>>   	log_test "$test_name"
>>   }
>>   
>> +buffer_circulation_test()
>> +{
>> +	RET=0
>> +	local test_name="buffer circulation"
>> +	local tracefs="/sys/kernel/tracing"
>> +
>> +	setup_cleanup
>> +	setup_prepare
>> +
>> +	ping -c 1 -I $h1 $H2_IPV4 >/dev/null
>> +	if [ $? -ne 0 ]; then
>> +		check_err 1 "Ping failed"
>> +		log_test "$test_name"
>> +		return
>> +	fi
>> +
>> +	local rx_start=$(cat /sys/class/net/$h2/statistics/rx_packets)
>> +	local tx_start=$(cat /sys/class/net/$h1/statistics/tx_packets)
>> +
>> +	if [ -d "$tracefs/events/page_pool" ]; then
>> +		echo > "$tracefs/trace"
>> +		echo 1 > "$tracefs/events/page_pool/enable"
>> +	fi
>> +
>> +	iperf3 -s --bind-dev $h2 -p 5201 &>/dev/null &
>> +	local server_pid=$!
>> +	sleep 1
>> +
>> +	if ! kill -0 $server_pid 2>/dev/null; then
>> +		if [ -d "$tracefs/events/page_pool" ]; then
>> +			echo 0 > "$tracefs/events/page_pool/enable"
>> +		fi
>> +		check_err 1 "iperf3 server died"
>> +		log_test "$test_name"
>> +		return
>> +	fi
>> +
>> +	iperf3 -c $H2_IPV4 --bind-dev $h1 -p 5201 -t 5 >/dev/null 2>&1
> 
> is using hard coded ports like this fine?
> running several in parallel will fail ...

I will use a random port in the ephemeral range to avoid
conflicts when running tests in parallel. Will fix it in v3.

> 
> 
>> +	local iperf_ret=$?
>> +
>> +	kill $server_pid 2>/dev/null || true
>> +	wait $server_pid 2>/dev/null || true
>> +
>> +	if [ -d "$tracefs/events/page_pool" ]; then
>> +		echo 0 > "$tracefs/events/page_pool/enable"
>> +		local trace="$tracefs/trace"
>> +		local hold=$(grep -c "page_pool_state_hold" "$trace" 2>/dev/null)
>> +		local release=$(grep -c "page_pool_state_release" "$trace" 2>/dev/null)
>> +		log_info "page_pool events: hold=${hold:-0}, release=${release:-0}"
>> +	fi
>> +
>> +	local rx_end=$(cat /sys/class/net/$h2/statistics/rx_packets)
>> +	local tx_end=$(cat /sys/class/net/$h1/statistics/tx_packets)
>> +	local rx_delta=$((rx_end - rx_start))
>> +	local tx_delta=$((tx_end - tx_start))
>> +
>> +	log_info "Circulated TX:$tx_delta RX:$rx_delta"
>> +
>> +	if [ $iperf_ret -ne 0 ]; then
>> +		check_err 1 "iperf3 failed"
>> +	elif [ "$rx_delta" -lt 10000 ]; then
>> +		check_err 1 "Too few packets: $rx_delta"
>> +	fi
>> +
>> +	log_test "$test_name"
>> +}
>> +
>>   setup_prepare()
>>   {
>>   	virtio_device_rebind $h1
>> -- 
>> 2.47.3
>