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Message-Id: <20240730184120.4089835-4-zijianzhang@bytedance.com>
Date: Tue, 30 Jul 2024 18:41:20 +0000
From: zijianzhang@...edance.com
To: netdev@...r.kernel.org
Cc: linux-api@...r.kernel.org,
willemdebruijn.kernel@...il.com,
almasrymina@...gle.com,
edumazet@...gle.com,
davem@...emloft.net,
kuba@...nel.org,
pabeni@...hat.com,
dsahern@...nel.org,
axboe@...nel.dk,
shuah@...nel.org,
linux-kselftest@...r.kernel.org,
cong.wang@...edance.com,
xiaochun.lu@...edance.com,
Zijian Zhang <zijianzhang@...edance.com>
Subject: [PATCH net-next v8 3/3] selftests: add MSG_ZEROCOPY msg_control notification test
From: Zijian Zhang <zijianzhang@...edance.com>
We update selftests/net/msg_zerocopy.c to accommodate the new mechanism,
cfg_notification_limit has the same semantics for both methods. Test
results are as follows, we update skb_orphan_frags_rx to the same as
skb_orphan_frags to support zerocopy in the localhost test.
cfg_notification_limit = 1, both method get notifications after 1 calling
of sendmsg. In this case, the new method has around 17% cpu savings in TCP
and 23% cpu savings in UDP.
+---------------------+---------+---------+---------+---------+
| Test Type / Protocol| TCP v4 | TCP v6 | UDP v4 | UDP v6 |
+---------------------+---------+---------+---------+---------+
| ZCopy (MB) | 7523 | 7706 | 7489 | 7304 |
+---------------------+---------+---------+---------+---------+
| New ZCopy (MB) | 8834 | 8993 | 9053 | 9228 |
+---------------------+---------+---------+---------+---------+
| New ZCopy / ZCopy | 117.42% | 116.70% | 120.88% | 126.34% |
+---------------------+---------+---------+---------+---------+
cfg_notification_limit = 32, both get notifications after 32 calling of
sendmsg, which means more chances to coalesce notifications, and less
overhead of poll + recvmsg for the original method. In this case, the new
method has around 7% cpu savings in TCP and slightly better cpu usage in
UDP. In the env of selftest, notifications of TCP are more likely to be
out of order than UDP, it's easier to coalesce more notifications in UDP.
The original method can get one notification with range of 32 in a recvmsg
most of the time. In TCP, most notifications' range is around 2, so the
original method needs around 16 recvmsgs to get notified in one round.
That's the reason for the "New ZCopy / ZCopy" diff in TCP and UDP here.
+---------------------+---------+---------+---------+---------+
| Test Type / Protocol| TCP v4 | TCP v6 | UDP v4 | UDP v6 |
+---------------------+---------+---------+---------+---------+
| ZCopy (MB) | 8842 | 8735 | 10072 | 9380 |
+---------------------+---------+---------+---------+---------+
| New ZCopy (MB) | 9366 | 9477 | 10108 | 9385 |
+---------------------+---------+---------+---------+---------+
| New ZCopy / ZCopy | 106.00% | 108.28% | 100.31% | 100.01% |
+---------------------+---------+---------+---------+---------+
In conclusion, when notification interval is small or notifications are
hard to be coalesced, the new mechanism is highly recommended. Otherwise,
the performance gain from the new mechanism is very limited.
Signed-off-by: Zijian Zhang <zijianzhang@...edance.com>
Signed-off-by: Xiaochun Lu <xiaochun.lu@...edance.com>
---
tools/testing/selftests/net/msg_zerocopy.c | 101 ++++++++++++++++++--
tools/testing/selftests/net/msg_zerocopy.sh | 1 +
2 files changed, 95 insertions(+), 7 deletions(-)
diff --git a/tools/testing/selftests/net/msg_zerocopy.c b/tools/testing/selftests/net/msg_zerocopy.c
index 7ea5fb28c93d..cf227f0011b5 100644
--- a/tools/testing/selftests/net/msg_zerocopy.c
+++ b/tools/testing/selftests/net/msg_zerocopy.c
@@ -66,6 +66,10 @@
#define SO_ZEROCOPY 60
#endif
+#ifndef SCM_ZC_NOTIFICATION
+#define SCM_ZC_NOTIFICATION 78
+#endif
+
#ifndef SO_EE_CODE_ZEROCOPY_COPIED
#define SO_EE_CODE_ZEROCOPY_COPIED 1
#endif
@@ -74,6 +78,14 @@
#define MSG_ZEROCOPY 0x4000000
#endif
+#define ZC_INFO_ARR_SIZE (ZC_NOTIFICATION_MAX * sizeof(struct zc_info_elem))
+#define ZC_INFO_SIZE (sizeof(struct zc_info) + ZC_INFO_ARR_SIZE)
+
+enum notification_type {
+ MSG_ZEROCOPY_NOTIFY_ERRQUEUE = 1,
+ MSG_ZEROCOPY_NOTIFY_SENDMSG = 2,
+};
+
static int cfg_cork;
static bool cfg_cork_mixed;
static int cfg_cpu = -1; /* default: pin to last cpu */
@@ -86,7 +98,7 @@ static int cfg_runtime_ms = 4200;
static int cfg_verbose;
static int cfg_waittime_ms = 500;
static int cfg_notification_limit = 32;
-static bool cfg_zerocopy;
+static enum notification_type cfg_zerocopy;
static socklen_t cfg_alen;
static struct sockaddr_storage cfg_dst_addr;
@@ -97,6 +109,8 @@ static long packets, bytes, completions, expected_completions;
static int zerocopied = -1;
static uint32_t next_completion;
static uint32_t sends_since_notify;
+static char zc_ckbuf[CMSG_SPACE(ZC_INFO_SIZE)];
+static bool added_zcopy_info;
static unsigned long gettimeofday_ms(void)
{
@@ -182,7 +196,26 @@ static void add_zcopy_cookie(struct msghdr *msg, uint32_t cookie)
memcpy(CMSG_DATA(cm), &cookie, sizeof(cookie));
}
-static bool do_sendmsg(int fd, struct msghdr *msg, bool do_zerocopy, int domain)
+static void add_zcopy_info(struct msghdr *msg)
+{
+ struct zc_info *zc_info;
+ struct cmsghdr *cm;
+
+ if (!msg->msg_control)
+ error(1, errno, "NULL user arg");
+ cm = (struct cmsghdr *)msg->msg_control;
+ cm->cmsg_len = CMSG_LEN(ZC_INFO_SIZE);
+ cm->cmsg_level = SOL_SOCKET;
+ cm->cmsg_type = SCM_ZC_NOTIFICATION;
+
+ zc_info = (struct zc_info *)CMSG_DATA(cm);
+ zc_info->size = ZC_NOTIFICATION_MAX;
+
+ added_zcopy_info = true;
+}
+
+static bool do_sendmsg(int fd, struct msghdr *msg,
+ enum notification_type do_zerocopy, int domain)
{
int ret, len, i, flags;
static uint32_t cookie;
@@ -200,6 +233,12 @@ static bool do_sendmsg(int fd, struct msghdr *msg, bool do_zerocopy, int domain)
msg->msg_controllen = CMSG_SPACE(sizeof(cookie));
msg->msg_control = (struct cmsghdr *)ckbuf;
add_zcopy_cookie(msg, ++cookie);
+ } else if (do_zerocopy == MSG_ZEROCOPY_NOTIFY_SENDMSG &&
+ sends_since_notify + 1 >= cfg_notification_limit) {
+ memset(&msg->msg_control, 0, sizeof(msg->msg_control));
+ msg->msg_controllen = CMSG_SPACE(ZC_INFO_SIZE);
+ msg->msg_control = (struct cmsghdr *)zc_ckbuf;
+ add_zcopy_info(msg);
}
}
@@ -218,7 +257,7 @@ static bool do_sendmsg(int fd, struct msghdr *msg, bool do_zerocopy, int domain)
if (do_zerocopy && ret)
expected_completions++;
}
- if (do_zerocopy && domain == PF_RDS) {
+ if (msg->msg_control) {
msg->msg_control = NULL;
msg->msg_controllen = 0;
}
@@ -466,6 +505,44 @@ static void do_recv_completions(int fd, int domain)
sends_since_notify = 0;
}
+static void do_recv_completions2(void)
+{
+ struct cmsghdr *cm = (struct cmsghdr *)zc_ckbuf;
+ struct zc_info *zc_info;
+ __u32 hi, lo, range;
+ __u8 zerocopy;
+ int i;
+
+ zc_info = (struct zc_info *)CMSG_DATA(cm);
+ for (i = 0; i < zc_info->size; i++) {
+ hi = zc_info->arr[i].hi;
+ lo = zc_info->arr[i].lo;
+ zerocopy = zc_info->arr[i].zerocopy;
+ range = hi - lo + 1;
+
+ if (cfg_verbose && lo != next_completion)
+ fprintf(stderr, "gap: %u..%u does not append to %u\n",
+ lo, hi, next_completion);
+ next_completion = hi + 1;
+
+ if (zerocopied == -1) {
+ zerocopied = zerocopy;
+ } else if (zerocopied != zerocopy) {
+ fprintf(stderr, "serr: inconsistent\n");
+ zerocopied = zerocopy;
+ }
+
+ completions += range;
+ sends_since_notify -= range;
+
+ if (cfg_verbose >= 2)
+ fprintf(stderr, "completed: %u (h=%u l=%u)\n",
+ range, hi, lo);
+ }
+
+ added_zcopy_info = false;
+}
+
/* Wait for all remaining completions on the errqueue */
static void do_recv_remaining_completions(int fd, int domain)
{
@@ -553,11 +630,16 @@ static void do_tx(int domain, int type, int protocol)
else
do_sendmsg(fd, &msg, cfg_zerocopy, domain);
- if (cfg_zerocopy && sends_since_notify >= cfg_notification_limit)
+ if (cfg_zerocopy == MSG_ZEROCOPY_NOTIFY_ERRQUEUE &&
+ sends_since_notify >= cfg_notification_limit)
do_recv_completions(fd, domain);
+ if (cfg_zerocopy == MSG_ZEROCOPY_NOTIFY_SENDMSG &&
+ added_zcopy_info)
+ do_recv_completions2();
+
while (!do_poll(fd, POLLOUT)) {
- if (cfg_zerocopy)
+ if (cfg_zerocopy == MSG_ZEROCOPY_NOTIFY_ERRQUEUE)
do_recv_completions(fd, domain);
}
@@ -715,7 +797,7 @@ static void parse_opts(int argc, char **argv)
cfg_payload_len = max_payload_len;
- while ((c = getopt(argc, argv, "46c:C:D:i:l:mp:rs:S:t:vz")) != -1) {
+ while ((c = getopt(argc, argv, "46c:C:D:i:l:mnp:rs:S:t:vz")) != -1) {
switch (c) {
case '4':
if (cfg_family != PF_UNSPEC)
@@ -749,6 +831,9 @@ static void parse_opts(int argc, char **argv)
case 'm':
cfg_cork_mixed = true;
break;
+ case 'n':
+ cfg_zerocopy = MSG_ZEROCOPY_NOTIFY_SENDMSG;
+ break;
case 'p':
cfg_port = strtoul(optarg, NULL, 0);
break;
@@ -768,7 +853,7 @@ static void parse_opts(int argc, char **argv)
cfg_verbose++;
break;
case 'z':
- cfg_zerocopy = true;
+ cfg_zerocopy = MSG_ZEROCOPY_NOTIFY_ERRQUEUE;
break;
}
}
@@ -779,6 +864,8 @@ static void parse_opts(int argc, char **argv)
error(1, 0, "-D <server addr> required for PF_RDS\n");
if (!cfg_rx && !saddr)
error(1, 0, "-S <client addr> required for PF_RDS\n");
+ if (cfg_zerocopy == MSG_ZEROCOPY_NOTIFY_SENDMSG)
+ error(1, 0, "PF_RDS does not support ZC_NOTIF_SENDMSG");
}
setup_sockaddr(cfg_family, daddr, &cfg_dst_addr);
setup_sockaddr(cfg_family, saddr, &cfg_src_addr);
diff --git a/tools/testing/selftests/net/msg_zerocopy.sh b/tools/testing/selftests/net/msg_zerocopy.sh
index 89c22f5320e0..022a6936d86f 100755
--- a/tools/testing/selftests/net/msg_zerocopy.sh
+++ b/tools/testing/selftests/net/msg_zerocopy.sh
@@ -118,4 +118,5 @@ do_test() {
do_test "${EXTRA_ARGS}"
do_test "-z ${EXTRA_ARGS}"
+do_test "-n ${EXTRA_ARGS}"
echo ok
--
2.20.1
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