[PATCH v2 4/4] selftests: net: udpgso_bench_tx: Cater for pending datagrams zerocopy benchmarking

Andrei Gherzan
2023-01-31T13:06:12Z

The test tool can check that the zerocopy number of completions value is
valid taking into consideration the number of datagram send calls. This can
catch the system into a state where the datagrams are still in the system
(for example in a qdisk, waiting for the network interface to return a
completion notification, etc).

This change adds a retry logic of computing the number of completions up to
a configurable (via CLI) timeout (default: 2 seconds).

Signed-off-by: Andrei Gherzan <andrei.gherzan@canonical.com>
---
tools/testing/selftests/net/udpgso_bench_tx.c | 38 +++++++++++++++----
1 file changed, 30 insertions(+), 8 deletions(-)

diff --git a/tools/testing/selftests/net/udpgso_bench_tx.c b/tools/testing/selftests/net/udpgso_bench_tx.c
index b47b5c32039f..5a29b5f24023 100644
--- a/tools/testing/selftests/net/udpgso_bench_tx.c
+++ b/tools/testing/selftests/net/udpgso_bench_tx.c
@@ -62,6 +62,7 @@ static int cfg_payload_len = (1472 * 42);
static int cfg_port = 8000;
static int cfg_runtime_ms = -1;
static bool cfg_poll;
+static int cfg_poll_loop_timeout_ms = 2000;
static bool cfg_segment;
static bool cfg_sendmmsg;
static bool cfg_tcp;
@@ -235,16 +236,17 @@ static void flush_errqueue_recv(int fd)
}
}

-static void flush_errqueue(int fd, const bool do_poll)
+static void flush_errqueue(int fd, const bool do_poll,
+ unsigned long poll_timeout, const bool poll_err)
{
if (do_poll) {
struct pollfd fds = {0};
int ret;

fds.fd = fd;
- ret = poll(&fds, 1, 500);
+ ret = poll(&fds, 1, poll_timeout);
if (ret == 0) {
- if (cfg_verbose)
+ if ((cfg_verbose) && (poll_err))
fprintf(stderr, "poll timeout\n");
} else if (ret < 0) {
error(1, errno, "poll");
@@ -254,6 +256,22 @@ static void flush_errqueue(int fd, const bool do_poll)
flush_errqueue_recv(fd);
}

+static void flush_errqueue_retry(int fd, const bool do_poll, unsigned long num_sends)
+{
+ unsigned long tnow, tstop;
+ bool first_try = true;
+
+ tnow = gettimeofday_ms();
+ tstop = tnow + cfg_poll_loop_timeout_ms;
+ do {
+ flush_errqueue(fd, do_poll, tstop - tnow, first_try);
+ first_try = false;
+ if (!do_poll)
+ usleep(1000); // a throttling delay if polling is enabled
+ tnow = gettimeofday_ms();
+ } while ((stat_zcopies != num_sends) && (tnow < tstop));
+}
+
static int send_tcp(int fd, char *data)
{
int ret, done = 0, count = 0;
@@ -413,8 +431,9 @@ static int send_udp_segment(int fd, char *data)

static void usage(const char *filepath)
{
- error(1, 0, "Usage: %s [-46acmHPtTuvz] [-C cpu] [-D dst ip] [-l secs] [-M messagenr] [-p port] [-s sendsize] [-S gsosize]",
- filepath);
+ error(1, 0,
+ "Usage: %s [-46acmHPtTuvz] [-C cpu] [-D dst ip] [-l secs] [-L secs] [-M messagenr] [-p port] [-s sendsize] [-S gsosize]",
+ filepath);
}

static void parse_opts(int argc, char **argv)
@@ -423,7 +442,7 @@ static void parse_opts(int argc, char **argv)
int max_len, hdrlen;
int c;

- while ((c = getopt(argc, argv, "46acC:D:Hl:mM:p:s:PS:tTuvz")) != -1) {
+ while ((c = getopt(argc, argv, "46acC:D:Hl:L:mM:p:s:PS:tTuvz")) != -1) {
switch (c) {
case '4':
if (cfg_family != PF_UNSPEC)
@@ -452,6 +471,9 @@ static void parse_opts(int argc, char **argv)
case 'l':
cfg_runtime_ms = strtoul(optarg, NULL, 10) * 1000;
break;
+ case 'L':
+ cfg_poll_loop_timeout_ms = strtoul(optarg, NULL, 10) * 1000;
+ break;
case 'm':
cfg_sendmmsg = true;
break;
@@ -679,7 +701,7 @@ int main(int argc, char **argv)
num_sends += send_udp(fd, buf[i]);
num_msgs++;
if ((cfg_zerocopy && ((num_msgs & 0xF) == 0)) || cfg_tx_tstamp)
- flush_errqueue(fd, cfg_poll);
+ flush_errqueue(fd, cfg_poll, 500, true);

if (cfg_msg_nr && num_msgs >= cfg_msg_nr)
break;
@@ -698,7 +720,7 @@ int main(int argc, char **argv)
} while (!interrupted && (cfg_runtime_ms == -1 || tnow < tstop));

if (cfg_zerocopy || cfg_tx_tstamp)
- flush_errqueue(fd, true);
+ flush_errqueue_retry(fd, true, num_sends);

if (close(fd))
error(1, errno, "close");
--
2.34.1