diff mbox series

[net-next,v7,3/3] selftests: add MSG_ZEROCOPY msg_control notification test

Message ID 20240708210405.870930-4-zijianzhang@bytedance.com (mailing list archive)
State Changes Requested
Delegated to: Netdev Maintainers
Headers show
Series net: A lightweight zero-copy notification | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next, async
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 8 this patch: 8
netdev/build_tools success Errors and warnings before: 0 this patch: 0
netdev/cc_maintainers warning 4 maintainers not CCed: kuba@kernel.org linux-kselftest@vger.kernel.org shuah@kernel.org pabeni@redhat.com
netdev/build_clang success Errors and warnings before: 8 this patch: 8
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success net selftest script(s) already in Makefile
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 8 this patch: 8
netdev/checkpatch warning CHECK: braces {} should be used on all arms of this statement WARNING: line length of 84 exceeds 80 columns WARNING: line length of 91 exceeds 80 columns
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Zijian Zhang July 8, 2024, 9:04 p.m. UTC 
From: Zijian Zhang <zijianzhang@bytedance.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 context of selftest, notifications of TCP are more likely to
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@bytedance.com>
Signed-off-by: Xiaochun Lu <xiaochun.lu@bytedance.com>
---
 tools/testing/selftests/net/msg_zerocopy.c  | 111 ++++++++++++++++++--
 tools/testing/selftests/net/msg_zerocopy.sh |   1 +
 2 files changed, 105 insertions(+), 7 deletions(-)

Comments

Simon Horman July 9, 2024, 9:19 a.m. UTC | #1 
+ Dave Miller, Jakub Kicinski, Paolo Abeni, Shuah Khan,
  linux-kselftest@vger.kernel.org

On Mon, Jul 08, 2024 at 09:04:05PM +0000, zijianzhang@bytedance.com wrote:
> From: Zijian Zhang <zijianzhang@bytedance.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 context of selftest, notifications of TCP are more likely to
> 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@bytedance.com>
> Signed-off-by: Xiaochun Lu <xiaochun.lu@bytedance.com>
> ---
>  tools/testing/selftests/net/msg_zerocopy.c  | 111 ++++++++++++++++++--
>  tools/testing/selftests/net/msg_zerocopy.sh |   1 +
>  2 files changed, 105 insertions(+), 7 deletions(-)
> 
> diff --git a/tools/testing/selftests/net/msg_zerocopy.c b/tools/testing/selftests/net/msg_zerocopy.c

...

> @@ -466,6 +504,44 @@ 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;
> +		}

nit: If any arms of a conditional have {}, then all arms should have them

> +
> +		completions += range;
> +
> +		if (cfg_verbose >= 2)
> +			fprintf(stderr, "completed: %u (h=%u l=%u)\n",
> +				range, hi, lo);
> +	}
> +
> +	sends_since_notify = 0;
> +	added_zcopy_info = false;
> +}

...
diff mbox series

Patch

diff --git a/tools/testing/selftests/net/msg_zerocopy.c b/tools/testing/selftests/net/msg_zerocopy.c
index 7ea5fb28c93d..064d2aaf7a2c 100644
--- a/tools/testing/selftests/net/msg_zerocopy.c
+++ b/tools/testing/selftests/net/msg_zerocopy.c
@@ -1,3 +1,4 @@ 
+// SPDX-License-Identifier: GPL-2.0
 /* Evaluate MSG_ZEROCOPY
  *
  * Send traffic between two processes over one of the supported
@@ -66,6 +67,10 @@ 
 #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 +79,11 @@ 
 #define MSG_ZEROCOPY	0x4000000
 #endif
 
+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 +96,7 @@  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 +107,9 @@  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;
+static int	zc_info_size;
+static bool	added_zcopy_info;
 
 static unsigned long gettimeofday_ms(void)
 {
@@ -182,7 +195,26 @@  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 = cfg_notification_limit;
+
+	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 +232,12 @@  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 +256,7 @@  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 +504,44 @@  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;
+
+		if (cfg_verbose >= 2)
+			fprintf(stderr, "completed: %u (h=%u l=%u)\n",
+				range, hi, lo);
+	}
+
+	sends_since_notify = 0;
+	added_zcopy_info = false;
+}
+
 /* Wait for all remaining completions on the errqueue */
 static void do_recv_remaining_completions(int fd, int domain)
 {
@@ -541,6 +617,14 @@  static void do_tx(int domain, int type, int protocol)
 				    sizeof(struct sockaddr_in6));
 	}
 
+	if (cfg_zerocopy == MSG_ZEROCOPY_NOTIFY_SENDMSG) {
+		zc_info_size = sizeof(struct zc_info) +
+			       sizeof(struct zc_info_elem) * cfg_notification_limit;
+		zc_ckbuf = (char *)malloc(CMSG_SPACE(zc_info_size));
+		if (!zc_ckbuf)
+			error(1, errno, "zc_ckbuf malloc failed");
+	}
+
 	iov[2].iov_base = payload;
 	iov[2].iov_len = cfg_payload_len;
 	msg.msg_iovlen++;
@@ -553,11 +637,16 @@  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);
 		}
 
@@ -566,6 +655,9 @@  static void do_tx(int domain, int type, int protocol)
 	if (cfg_zerocopy)
 		do_recv_remaining_completions(fd, domain);
 
+	if (cfg_zerocopy == MSG_ZEROCOPY_NOTIFY_SENDMSG)
+		free(zc_ckbuf);
+
 	if (close(fd))
 		error(1, errno, "close");
 
@@ -715,7 +807,7 @@  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 +841,9 @@  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 +863,7 @@  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 +874,8 @@  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 MSG_ZEROCOPY_NOTIFY_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