@@ -390,6
+414,42 @@ static size_t tap_send_frames_passt(const struct ctx *c,
return i;
}
+/**
+ * tap_send_iov_passt() - Send out multiple prepared frames
...I would argue that this function prepares frames as well. Maybe:
* tap_send_iov_passt() - Prepare TCP_IOV_VNET parts and send multiple frames
+ * @c: Execution context
+ * @iov: Array of frames, each frames is divided in an array of iovecs.
+ * The first entry of the iovec is updated to point to an
+ * uint32_t storing the frame length.
* @iov: Array of frames, each one a vector of parts, TCP_IOV_VNET blank
+ * @n: Number of frames in @iov
+ *
+ * Return: number of frames actually sent
+ */
+static size_t tap_send_iov_passt(const struct ctx *c,
+ struct iovec iov[][TCP_IOV_NUM],
+ size_t n)
+{
+ unsigned int i;
+
+ for (i = 0; i < n; i++) {
+ uint32_t vnet_len;
+ int j;
+
+ vnet_len = 0;
This could be initialised in the declaration (yes, it's "reset" at
every loop iteration).
+ for (j = TCP_IOV_ETH; j < TCP_IOV_NUM;
j++)
+ vnet_len += iov[i][j].iov_len;
+
+ vnet_len = htonl(vnet_len);
+ iov[i][TCP_IOV_VNET].iov_base = &vnet_len;
+ iov[i][TCP_IOV_VNET].iov_len = sizeof(vnet_len);
+
+ if (!tap_send_frames_passt(c, iov[i], TCP_IOV_NUM))
...which would now send a single frame at a time, but actually it can
already send everything in one shot because it's using sendmsg(), if you
move it outside of the loop and do something like (untested):
return tap_send_frames_passt(c, iov, TCP_IOV_NUM * n);
> + break;
> + }
> +
> + return i;
> +
> +}
> +
I tried to do something like that but I have a performance drop:
static size_t tap_send_iov_passt(const struct ctx *c,
struct iovec iov[][TCP_IOV_NUM],
size_t n)
{
unsigned int i;
uint32_t vnet_len[n];
for (i = 0; i < n; i++) {
int j;
vnet_len[i] = 0;
for (j = TCP_IOV_ETH; j < TCP_IOV_NUM; j++)
vnet_len[i] += iov[i][j].iov_len;
vnet_len[i] = htonl(vnet_len[i]);
iov[i][TCP_IOV_VNET].iov_base = &vnet_len[i];
iov[i][TCP_IOV_VNET].iov_len = sizeof(uint32_t);
}
return tap_send_frames_passt(c, &iov[0][0], TCP_IOV_NUM * n) /
TCP_IOV_NUM;
}
iperf3 -c localhost -p 10001 -t 60 -4
berfore
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-60.00 sec 33.0 GBytes 4.72 Gbits/sec 1 sender
[ 5] 0.00-60.06 sec 33.0 GBytes 4.72 Gbits/sec receiver
after:
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-60.00 sec 18.2 GBytes 2.60 Gbits/sec 0 sender
[ 5] 0.00-60.07 sec 18.2 GBytes 2.60 Gbits/sec receiver