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Message-ID: <6400bd699f568_20743e2082b@willemb.c.googlers.com.notmuch>
Date: Thu, 02 Mar 2023 10:14:49 -0500
From: Willem de Bruijn <willemdebruijn.kernel@...il.com>
To: yang.yang29@....com.cn, davem@...emloft.net
Cc: edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
shuah@...nel.org, netdev@...r.kernel.org,
linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org,
zhang.yunkai@....com.cn, xu.xin16@....com.cn,
jiang.xuexin@....com.cn
Subject: RE: [PATCH linux-next v2] selftests: net: udpgso_bench_tx: Add test
for IP fragmentation of UDP packets
yang.yang29@ wrote:
> From: zhang yunkai (CGEL ZTE) <zhang.yunkai@....com.cn>
>
> The UDP GSO bench only tests the performance of userspace payload splitting
> and UDP GSO. But we are also concerned about the performance comparing with
> IP fragmentation and UDP GSO. In other words comparing IP fragmentation and
> segmentation.
>
> So we add testcase of IP fragmentation of UDP packets, then user would easy
> to get to know the performance promotion of UDP GSO compared with IP
> fragmentation. We add a new option "-f", which is to send big data using
> IP fragmentation instead of using UDP GSO or userspace payload splitting.
>
> In the QEMU environment we could see obvious promotion of UDP GSO.
> The first test is to get the performance of userspace payload splitting.
> bash# udpgso_bench_tx -l 4 -4 -D "$DST"
> udp tx: 21 MB/s 15162 calls/s 361 msg/s
> udp tx: 21 MB/s 15498 calls/s 369 msg/s
> udp tx: 18 MB/s 13440 calls/s 320 msg/s
> udp tx: 19 MB/s 13776 calls/s 328 msg/s
>
> The second test is to get the performance of IP fragmentation.
> bash# udpgso_bench_tx -l 4 -4 -D "$DST" -f
> udp tx: 41 MB/s 711 calls/s 711 msg/s
> udp tx: 41 MB/s 700 calls/s 700 msg/s
> udp tx: 43 MB/s 738 calls/s 738 msg/s
> udp tx: 40 MB/s 693 calls/s 693 msg/s
>
> The third test is to get the performance of UDP GSO.
> bash# udpgso_bench_tx -l 4 -4 -D "$DST" -S 0
> udp tx: 45 MB/s 775 calls/s 775 msg/s
> udp tx: 47 MB/s 800 calls/s 800 msg/s
> udp tx: 47 MB/s 814 calls/s 814 msg/s
> udp tx: 47 MB/s 812 calls/s 812 msg/s
>
> v2: Suggested by Willem de Bruijn <willemdebruijn.kernel@...il.com>
> - Use IP_PMTUDISC_OMIT to disable PMTU discovery and to avoid send
> returning with error after ICMP destination unreachable messages if MTU
> is exceeded in the path.
Did you actually observe a difference in behavior with this change?
The man page summarizes it better than I could:
IP_PMTUDISC_DO forces the don't-fragment flag to be set on all
outgoing packets.[..] The kernel will reject (with EMSGSIZE)
datagrams that are bigger than the known path MTU.
I would think your fragmentation test fails with that option set.
net-next is still closed btw.
> Signed-off-by: zhang yunkai (CGEL ZTE) <zhang.yunkai@....com.cn>
> Reviewed-by: xu xin (CGEL ZTE) <xu.xin16@....com.cn>
> Reviewed-by: Yang Yang (CGEL ZTE) <yang.yang29@....com.cn>
> Cc: Xuexin Jiang (CGEL ZTE) <jiang.xuexin@....com.cn>
> ---
> tools/testing/selftests/net/udpgso_bench_tx.c | 49 ++++++++++++++++++++++-----
> 1 file changed, 40 insertions(+), 9 deletions(-)
>
> diff --git a/tools/testing/selftests/net/udpgso_bench_tx.c b/tools/testing/selftests/net/udpgso_bench_tx.c
> index 477392715a9a..b3333b39bb87 100644
> --- a/tools/testing/selftests/net/udpgso_bench_tx.c
> +++ b/tools/testing/selftests/net/udpgso_bench_tx.c
> @@ -64,6 +64,7 @@ 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_fragment;
> static bool cfg_sendmmsg;
> static bool cfg_tcp;
> static uint32_t cfg_tx_ts = SOF_TIMESTAMPING_TX_SOFTWARE;
> @@ -375,6 +376,21 @@ static int send_udp_sendmmsg(int fd, char *data)
> return ret;
> }
>
> +static int send_udp_fragment(int fd, char *data)
> +{
> + int ret;
> +
> + ret = sendto(fd, data, cfg_payload_len, cfg_zerocopy ? MSG_ZEROCOPY : 0,
> + cfg_connected ? NULL : (void *)&cfg_dst_addr,
> + cfg_connected ? 0 : cfg_alen);
> + if (ret == -1)
> + error(1, errno, "write");
> + if (ret != cfg_payload_len)
> + error(1, errno, "write: %uB != %uB\n", ret, cfg_payload_len);
> +
> + return 1;
> +}
> +
> static void send_udp_segment_cmsg(struct cmsghdr *cm)
> {
> uint16_t *valp;
> @@ -429,7 +445,7 @@ 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] "
> + error(1, 0, "Usage: %s [-46acfmHPtTuvz] [-C cpu] [-D dst ip] [-l secs] "
> "[-L secs] [-M messagenr] [-p port] [-s sendsize] [-S gsosize]",
> filepath);
> }
> @@ -440,7 +456,7 @@ static void parse_opts(int argc, char **argv)
> int max_len, hdrlen;
> int c;
>
> - while ((c = getopt(argc, argv, "46acC:D:Hl:L:mM:p:s:PS:tTuvz")) != -1) {
> + while ((c = getopt(argc, argv, "46acC:D:fHl:L:mM:p:s:PS:tTuvz")) != -1) {
> switch (c) {
> case '4':
> if (cfg_family != PF_UNSPEC)
> @@ -469,6 +485,9 @@ static void parse_opts(int argc, char **argv)
> case 'l':
> cfg_runtime_ms = strtoul(optarg, NULL, 10) * 1000;
> break;
> + case 'f':
> + cfg_fragment = true;
> + break;
> case 'L':
> cfg_poll_loop_timeout_ms = strtoul(optarg, NULL, 10) * 1000;
> break;
> @@ -527,10 +546,10 @@ static void parse_opts(int argc, char **argv)
> error(1, 0, "must pass one of -4 or -6");
> if (cfg_tcp && !cfg_connected)
> error(1, 0, "connectionless tcp makes no sense");
> - if (cfg_segment && cfg_sendmmsg)
> - error(1, 0, "cannot combine segment offload and sendmmsg");
> - if (cfg_tx_tstamp && !(cfg_segment || cfg_sendmmsg))
> - error(1, 0, "Options -T and -H require either -S or -m option");
> + if ((cfg_segment + cfg_sendmmsg + cfg_fragment) > 1)
> + error(1, 0, "cannot combine segment offload, fragment and sendmmsg");
> + if (cfg_tx_tstamp && !(cfg_segment || cfg_sendmmsg || cfg_fragment))
> + error(1, 0, "Options -T and -H require either -S or -m or -f option");
>
> if (cfg_family == PF_INET)
> hdrlen = sizeof(struct iphdr) + sizeof(struct udphdr);
> @@ -551,14 +570,24 @@ static void set_pmtu_discover(int fd, bool is_ipv4)
> {
> int level, name, val;
>
> + /* IP fragmentation test uses IP_PMTUDISC_OMIT to disable PMTU discovery and
> + * to avoid send returning with error after ICMP destination unreachable
> + * messages if MTU is exceeded in the path.
> + */
> if (is_ipv4) {
> level = SOL_IP;
> name = IP_MTU_DISCOVER;
> - val = IP_PMTUDISC_DO;
> + if (cfg_segment)
> + val = IP_PMTUDISC_DO;
> + else if (cfg_fragment)
> + val = IP_PMTUDISC_OMIT;
> } else {
> level = SOL_IPV6;
> name = IPV6_MTU_DISCOVER;
> - val = IPV6_PMTUDISC_DO;
> + if (cfg_segment)
> + val = IPV6_PMTUDISC_DO;
> + else if (cfg_fragment)
> + val = IPV6_PMTUDISC_OMIT;
> }
>
> if (setsockopt(fd, level, name, &val, sizeof(val)))
> @@ -674,7 +703,7 @@ int main(int argc, char **argv)
> connect(fd, (void *)&cfg_dst_addr, cfg_alen))
> error(1, errno, "connect");
>
> - if (cfg_segment)
> + if (cfg_segment || cfg_fragment)
> set_pmtu_discover(fd, cfg_family == PF_INET);
>
> if (cfg_tx_tstamp)
> @@ -695,6 +724,8 @@ int main(int argc, char **argv)
> num_sends += send_udp_segment(fd, buf[i]);
> else if (cfg_sendmmsg)
> num_sends += send_udp_sendmmsg(fd, buf[i]);
> + else if (cfg_fragment)
> + num_sends += send_udp_fragment(fd, buf[i]);
> else
> num_sends += send_udp(fd, buf[i]);
> num_msgs++;
> --
> 2.15.2
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