Re: [RFC PATCH v1 12/12] test/vsock: MSG_ZEROCOPY support for vsock_perf

From: Stefano Garzarella
Date: Thu Feb 16 2023 - 10:30:45 EST

On Mon, Feb 06, 2023 at 07:06:32AM +0000, Arseniy Krasnov wrote:
To use this option pass '--zc' parameter:

--zerocopy or --zero-copy maybe better follow what we did with the other parameters :-)


./vsock_perf --zc --sender <cid> --port <port> --bytes <bytes to send>

With this option MSG_ZEROCOPY flag will be passed to the 'send()' call.

Signed-off-by: Arseniy Krasnov <AVKrasnov@xxxxxxxxxxxxxx>
---
tools/testing/vsock/vsock_perf.c | 127 +++++++++++++++++++++++++++++--
1 file changed, 120 insertions(+), 7 deletions(-)

diff --git a/tools/testing/vsock/vsock_perf.c b/tools/testing/vsock/vsock_perf.c
index a72520338f84..1d435be9b48e 100644
--- a/tools/testing/vsock/vsock_perf.c
+++ b/tools/testing/vsock/vsock_perf.c
@@ -18,6 +18,8 @@
#include <poll.h>
#include <sys/socket.h>
#include <linux/vm_sockets.h>
+#include <sys/mman.h>
+#include <linux/errqueue.h>

#define DEFAULT_BUF_SIZE_BYTES (128 * 1024)
#define DEFAULT_TO_SEND_BYTES (64 * 1024)
@@ -28,9 +30,14 @@
#define BYTES_PER_GB (1024 * 1024 * 1024ULL)
#define NSEC_PER_SEC (1000000000ULL)

+#ifndef SOL_VSOCK
+#define SOL_VSOCK 287
+#endif

I thought we use the current kernel headers when we compile the tests,
do we need to fix something in the makefile?

+
static unsigned int port = DEFAULT_PORT;
static unsigned long buf_size_bytes = DEFAULT_BUF_SIZE_BYTES;
static unsigned long vsock_buf_bytes = DEFAULT_VSOCK_BUF_BYTES;
+static bool zerocopy;

static void error(const char *s)
{
@@ -247,15 +254,74 @@ static void run_receiver(unsigned long rcvlowat_bytes)
close(fd);
}

+static void recv_completion(int fd)
+{
+ struct sock_extended_err *serr;
+ char cmsg_data[128];
+ struct cmsghdr *cm;
+ struct msghdr msg;
+ int ret;
+
+ msg.msg_control = cmsg_data;
+ msg.msg_controllen = sizeof(cmsg_data);
+
+ ret = recvmsg(fd, &msg, MSG_ERRQUEUE);
+ if (ret == -1)
+ return;
+
+ cm = CMSG_FIRSTHDR(&msg);
+ if (!cm) {
+ fprintf(stderr, "cmsg: no cmsg\n");
+ return;
+ }
+
+ if (cm->cmsg_level != SOL_VSOCK) {
+ fprintf(stderr, "cmsg: unexpected 'cmsg_level'\n");
+ return;
+ }
+
+ if (cm->cmsg_type) {
+ fprintf(stderr, "cmsg: unexpected 'cmsg_type'\n");
+ return;
+ }
+
+ serr = (void *)CMSG_DATA(cm);
+ if (serr->ee_origin != SO_EE_ORIGIN_ZEROCOPY) {
+ fprintf(stderr, "serr: wrong origin\n");
+ return;
+ }
+
+ if (serr->ee_errno) {
+ fprintf(stderr, "serr: wrong error code\n");
+ return;
+ }
+
+ if (zerocopy && (serr->ee_code & SO_EE_CODE_ZEROCOPY_COPIED))
+ fprintf(stderr, "warning: copy instead of zerocopy\n");
+}
+
+static void enable_so_zerocopy(int fd)
+{
+ int val = 1;
+
+ if (setsockopt(fd, SOL_SOCKET, SO_ZEROCOPY, &val, sizeof(val)))
+ error("setsockopt(SO_ZEROCOPY)");
+}
+
static void run_sender(int peer_cid, unsigned long to_send_bytes)
{
time_t tx_begin_ns;
time_t tx_total_ns;
size_t total_send;
+ time_t time_in_send;
void *data;
int fd;

- printf("Run as sender\n");
+ if (zerocopy)
+ printf("Run as sender MSG_ZEROCOPY\n");
+ else
+ printf("Run as sender\n");
+
printf("Connect to %i:%u\n", peer_cid, port);
printf("Send %lu bytes\n", to_send_bytes);
printf("TX buffer %lu bytes\n", buf_size_bytes);
@@ -265,25 +331,58 @@ static void run_sender(int peer_cid, unsigned long to_send_bytes)
if (fd < 0)
exit(EXIT_FAILURE);

- data = malloc(buf_size_bytes);
+ if (zerocopy) {
+ enable_so_zerocopy(fd);

- if (!data) {
- fprintf(stderr, "'malloc()' failed\n");
- exit(EXIT_FAILURE);
+ data = mmap(NULL, buf_size_bytes, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+ if (data == MAP_FAILED) {
+ perror("mmap");
+ exit(EXIT_FAILURE);
+ }
+ } else {
+ data = malloc(buf_size_bytes);
+
+ if (!data) {
+ fprintf(stderr, "'malloc()' failed\n");
+ exit(EXIT_FAILURE);
+ }
}

Eventually to simplify the code I think we can use the mmaped buffer in
both cases.


memset(data, 0, buf_size_bytes);
total_send = 0;
+ time_in_send = 0;
tx_begin_ns = current_nsec();

while (total_send < to_send_bytes) {
ssize_t sent;
+ size_t rest_bytes;
+ time_t before;
+
+ rest_bytes = to_send_bytes - total_send;

- sent = write(fd, data, buf_size_bytes);
+ before = current_nsec();
+ sent = send(fd, data, (rest_bytes > buf_size_bytes) ?
+ buf_size_bytes : rest_bytes,
+ zerocopy ? MSG_ZEROCOPY : 0);
+ time_in_send += (current_nsec() - before);

if (sent <= 0)
error("write");

+ if (zerocopy) {
+ struct pollfd fds = { 0 };
+
+ fds.fd = fd;

Which event are we waiting for here?

+
+ if (poll(&fds, 1, -1) < 0) {
+ perror("poll");
+ exit(EXIT_FAILURE);
+ }

We need this because we use only one buffer, but if we use more than
one, we could take full advantage of zerocopy, right?

Otherwise, I don't think it's a fair comparison with non-zerocopy.

Thanks,
Stefano

+
+ recv_completion(fd);
+ }
+
total_send += sent;
}

@@ -294,9 +393,14 @@ static void run_sender(int peer_cid, unsigned long to_send_bytes)
get_gbps(total_send * 8, tx_total_ns));
printf("total time in 'write()': %f sec\n",
(float)tx_total_ns / NSEC_PER_SEC);
+ printf("time in send %f\n", (float)time_in_send / NSEC_PER_SEC);

close(fd);
- free(data);
+
+ if (zerocopy)
+ munmap(data, buf_size_bytes);
+ else
+ free(data);
}

static const char optstring[] = "";
@@ -336,6 +440,11 @@ static const struct option longopts[] = {
.has_arg = required_argument,
.val = 'R',
},
+ {
+ .name = "zc",
+ .has_arg = no_argument,
+ .val = 'Z',
+ },
{},
};

@@ -351,6 +460,7 @@ static void usage(void)
" --help This message\n"
" --sender <cid> Sender mode (receiver default)\n"
" <cid> of the receiver to connect to\n"
+ " --zc Enable zerocopy\n"
" --port <port> Port (default %d)\n"
" --bytes <bytes>KMG Bytes to send (default %d)\n"
" --buf-size <bytes>KMG Data buffer size (default %d). In sender mode\n"
@@ -413,6 +523,9 @@ int main(int argc, char **argv)
case 'H': /* Help. */
usage();
break;
+ case 'Z': /* Zerocopy. */
+ zerocopy = true;
+ break;
default:
usage();
}
--
2.25.1