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

Andrei Gherzan
2023-01-31T16:32:11Z

On 23/01/31 05:22PM, Paolo Abeni wrote:
> On Tue, 2023-01-31 at 15:08 +0000, Andrei Gherzan wrote:
> > On 23/01/31 03:51PM, Paolo Abeni wrote:
> > > On Tue, 2023-01-31 at 13:04 +0000, Andrei Gherzan wrote:
> > > > 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
> > >
> > > Even if the kernel codying style is not very strictly enforced for
> > > self-tests, please avoid c++ style comments.
> > >
> > > More importantly, as Willem noded, this function is always called with
> > > do_poll == true. You should drop such argument and the related branch
> > > above.
> >
> > Agreed. I will drop.
> >
> > >
> > > > + 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);
> > >
> > > Please avoid introducing unnecessary white-space changes (no reason to
> > > move the usage text on a new line)
> >
> > The only reason why I've done this was to make scripts/checkpatch.pl
> > happy:
> >
> > WARNING: line length of 141 exceeds 100 columns
> > #83: FILE: tools/testing/selftests/net/udpgso_bench_tx.c:432:
> >
> > I can drop and ignore the warning, or maybe it would have been better to
> > just mention this in git message. What do you prefer?
>
> Long lines are allowed for (kernel) messages, to make them easily grep-
> able.
>
> In this specific case you can either append the new text to the message
> without introducing that strange indentation or even better break the
> usage string alike:
>
> "Usage: %s [-46acmHPtTuvz] [-C cpu] [-D dst ip] [-l secs] [-L secs]"
> " [-L secs] [-M messagenr] [-p port] [-s sendsize] [-S gsosize]"

Funny I went through this too but it also fails with:

WARNING: quoted string split across lines
#84: FILE: tools/testing/selftests/net/udpgso_bench_tx.c:433

This is how I usually do it but it seems like it's flagged too.

--
Andrei Gherzan