lib: Memory spike reduction for sh cmds at scale

lib/vty.c

@@ -345,8 +345,17 @@ int vty_out(struct vty *vty, const char *format, ...)
 	case VTY_SHELL_SERV:
 	case VTY_FILE:
 	default:
+		vty->vty_buf_size_written += strlen(filtered);
 		/* print without crlf replacement */
 		buffer_put(vty->obuf, (uint8_t *)filtered, strlen(filtered));
+		/* For every chunk of memory, we invoke vtysh_flush where we
+		 * put the data of collective vty->obuf Linked List items on the
+		 * socket and free the vty->obuf data.
+		 */
+		if (vty->vty_buf_size_written >= MAX_INTERMEDIATE_FLUSH) {
+			vty->vty_buf_size_written = 0;
+			vtysh_flush(vty);
+		}
 		break;
 	}
 
@@ -2141,6 +2150,21 @@ static void vtysh_accept(struct event *thread)
 		close(sock);
 		return;
 	}
+	/* Setting the SND buffer size to 16MB to increase the buffer size
+	 * the socket can hold before sending it to VTY shell
+	 */
+	uint32_t sndbufsize = SEND_BUF_MAX;
+	int ret;
+
+	ret = setsockopt(sock, SOL_SOCKET, SO_SNDBUF, (char *)&sndbufsize,
+			 sizeof(sndbufsize));
+	if (ret < 0) {
+		flog_err(EC_LIB_SOCKET,
+			 "Cannot set socket %d send buffer size, %s", sock,
+			 safe_strerror(errno));
+		close(sock);
+		return;
+	}
 	set_cloexec(sock);
 
 #ifdef VTYSH_DEBUG
@@ -2227,6 +2251,7 @@ static int vtysh_flush(struct vty *vty)
 		vty_close(vty);
 		return -1;
 	case BUFFER_EMPTY:
+		vty->vty_buf_size_written = 0;
 		break;
 	}
 	return 0;

lib/vty.h

@@ -236,6 +236,7 @@ struct vty {
 	uintptr_t mgmt_req_pending_data;
 	bool mgmt_locked_candidate_ds;
 	bool mgmt_locked_running_ds;
+	uint64_t vty_buf_size_written;
 };
 
 static inline void vty_push_context(struct vty *vty, int node, uint64_t id)
@@ -338,6 +339,12 @@ struct vty_arg {
 /* Vty read buffer size. */
 #define VTY_READ_BUFSIZ 512
 
+/* Vty max send buffer size (4096 * 4096). */
+#define SEND_BUF_MAX 16777216
+
+/* Vty flush intermediate size (32 * 4096). */
+#define MAX_INTERMEDIATE_FLUSH 131072
+
 /* Directory separator. */
 #ifndef DIRECTORY_SEP
 #define DIRECTORY_SEP '/'

vtysh/vtysh.c

@@ -4721,6 +4721,22 @@ static int vtysh_connect(struct vtysh_client *vclient)
 		close(sock);
 		return -1;
 	}
+	/* Setting the RCV buffer size to 16MB to increase the buffer size
+	 * the socket can hold after receving from other process
+	 */
+	uint32_t rcvbufsize = RCV_BUF_MAX;
+
+	ret = setsockopt(sock, SOL_SOCKET, SO_RCVBUF, (char *)&rcvbufsize,
+			 sizeof(rcvbufsize));
+	if (ret < 0) {
+#ifdef DEBUG
+		fprintf(stderr, "Cannot set socket %d rcv buffer size, %s\n",
+			sock, safe_strerror(errno));
+#endif /* DEBUG */
+		close(sock);
+		return -1;
+	}
+
 	vclient->fd = sock;
 
 	return 0;

vtysh/vtysh.h

@@ -35,6 +35,7 @@ extern struct event_loop *master;
 #define VTYSH_PATHD     0x80000
 #define VTYSH_PIM6D     0x100000
 #define VTYSH_MGMTD 0x200000
+#define RCV_BUF_MAX	16777216
 
 #define VTYSH_WAS_ACTIVE (-2)