From bd60438eeb1ebe9415b157398083b4910c7f0aa3 Mon Sep 17 00:00:00 2001 From: Willem de Bruijn Date: Mon, 31 Jul 2023 14:08:09 -0400 Subject: [PATCH] selftests/net: report rcv_mss in tcp_mmap tcp_mmap tests TCP_ZEROCOPY_RECEIVE. If 0% of data is received using mmap, this may be due to mss. Report rcv_mss to identify this cause. Output of a run failed due to too small mss: received 32768 MB (0 % mmap'ed) in 8.40458 s, 32.7057 Gbit cpu usage user:0.027922 sys:8.21126, 251.44 usec per MB, 3252 c-switches, rcv_mss 1428 Output on a successful run: received 32768 MB (99.9507 % mmap'ed) in 4.69023 s, 58.6064 Gbit cpu usage user:0.029172 sys:2.56105, 79.0473 usec per MB, 57591 c-switches, rcv_mss 4096 Suggested-by: Eric Dumazet Signed-off-by: Willem de Bruijn Signed-off-by: David S. Miller --- tools/testing/selftests/net/tcp_mmap.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/net/tcp_mmap.c b/tools/testing/selftests/net/tcp_mmap.c index 6e59b1461dcce..4fcce5150850d 100644 --- a/tools/testing/selftests/net/tcp_mmap.c +++ b/tools/testing/selftests/net/tcp_mmap.c @@ -153,6 +153,19 @@ static void *mmap_large_buffer(size_t need, size_t *allocated) return buffer; } +static uint32_t tcp_info_get_rcv_mss(int fd) +{ + socklen_t sz = sizeof(struct tcp_info); + struct tcp_info info; + + if (getsockopt(fd, IPPROTO_TCP, TCP_INFO, &info, &sz)) { + fprintf(stderr, "Error fetching TCP_INFO\n"); + return 0; + } + + return info.tcpi_rcv_mss; +} + void *child_thread(void *arg) { unsigned char digest[SHA256_DIGEST_LENGTH]; @@ -288,7 +301,7 @@ end: total_usec = 1000000*ru.ru_utime.tv_sec + ru.ru_utime.tv_usec + 1000000*ru.ru_stime.tv_sec + ru.ru_stime.tv_usec; printf("received %lg MB (%lg %% mmap'ed) in %lg s, %lg Gbit\n" - " cpu usage user:%lg sys:%lg, %lg usec per MB, %lu c-switches\n", + " cpu usage user:%lg sys:%lg, %lg usec per MB, %lu c-switches, rcv_mss %u\n", total / (1024.0 * 1024.0), 100.0*total_mmap/total, (double)delta_usec / 1000000.0, @@ -296,7 +309,8 @@ end: (double)ru.ru_utime.tv_sec + (double)ru.ru_utime.tv_usec / 1000000.0, (double)ru.ru_stime.tv_sec + (double)ru.ru_stime.tv_usec / 1000000.0, (double)total_usec/mb, - ru.ru_nvcsw); + ru.ru_nvcsw, + tcp_info_get_rcv_mss(fd)); } error: munmap(buffer, buffer_sz); -- 2.30.2