Add --bwlimit option contributed by Matthew Demicco and Jamie Gritton.

io.c

@@ -27,6 +27,8 @@
 /* if no timeout is specified then use a 60 second select timeout */
 #define SELECT_TIMEOUT 60
 
+extern int bwlimit;
+
 static int io_multiplexing_out;
 static int io_multiplexing_in;
 static int multiplex_in_fd;
@@ -388,6 +390,19 @@ static void writefd_unbuffered(int fd,char *buf,int len)
 				exit_cleanup(RERR_STREAMIO);
 			}
 
+			/* Sleep after writing to limit I/O bandwidth */
+			if (bwlimit)
+			{
+			    tv.tv_sec = 0;
+			    tv.tv_usec = ret * 1000 / bwlimit;
+			    while (tv.tv_usec > 1000000)
+			    {
+				tv.tv_sec++;
+				tv.tv_usec -= 1000000;
+			    }
+			    select(0, NULL, NULL, NULL, &tv);
+ 			}
+ 
 			total += ret;
 
 			if (io_timeout)

options.c

@@ -62,6 +62,7 @@ int safe_symlinks=0;
 int copy_unsafe_links=0;
 int block_size=BLOCK_SIZE;
 int size_only=0;
+int bwlimit=0;
 int delete_after=0;
 int only_existing=0;
 int max_delete=0;
@@ -159,6 +160,7 @@ void usage(enum logcode F)
   rprintf(F,"     --progress              show progress during transfer\n");  
   rprintf(F,"     --log-format=FORMAT     log file transfers using specified format\n");  
   rprintf(F,"     --password-file=FILE    get password from FILE\n");
+  rprintf(F,"     --bwlimit=KBPS          limit I/O bandwidth, KBytes per second\n");
   rprintf(F," -h, --help                  show this help screen\n");
 
   rprintf(F,"\n");
@@ -174,7 +176,7 @@ enum {OPT_VERSION, OPT_SUFFIX, OPT_SENDER, OPT_SERVER, OPT_EXCLUDE,
       OPT_COPY_UNSAFE_LINKS, OPT_SAFE_LINKS, OPT_COMPARE_DEST,
       OPT_LOG_FORMAT, OPT_PASSWORD_FILE, OPT_SIZE_ONLY, OPT_ADDRESS,
       OPT_DELETE_AFTER, OPT_EXISTING, OPT_MAX_DELETE, OPT_BACKUP_DIR, 
-      OPT_IGNORE_ERRORS};
+      OPT_IGNORE_ERRORS, OPT_BWLIMIT};
 
 static char *short_options = "oblLWHpguDCtcahvqrRIxnSe:B:T:zP";
 
@@ -235,6 +237,7 @@ static struct option long_options[] = {
   {"config",      1,     0,    OPT_CONFIG},
   {"port",        1,     0,    OPT_PORT},
   {"log-format",  1,     0,    OPT_LOG_FORMAT},
+  {"bwlimit",	  1,	 0,    OPT_BWLIMIT},
   {"address",     1,     0,    OPT_ADDRESS},
   {"max-delete",  1,     0,    OPT_MAX_DELETE},
   {"backup-dir",  1,     0,    OPT_BACKUP_DIR},
@@ -552,6 +555,10 @@ int parse_arguments(int argc, char *argv[], int frommain)
 		case OPT_LOG_FORMAT:
 			log_format = optarg;
 			break;
+	
+		case OPT_BWLIMIT:
+			bwlimit = atoi(optarg);
+			break;
 
 		case OPT_ADDRESS:
 			{
@@ -584,6 +591,8 @@ void server_options(char **args,int *argc)
 	static char bsize[30];
 	static char iotime[30];
 	static char mdelete[30];
+	static char bw[50];
+
 	int i, x;
 
 	args[ac++] = "--server";
@@ -655,6 +664,11 @@ void server_options(char **args,int *argc)
 		args[ac++] = iotime;
 	}    
 
+	if (bwlimit) {
+		slprintf(bw,sizeof(bw),"--bwlimit=%d",bwlimit);
+		args[ac++] = bw;
+	}
+
 	if (strcmp(backup_suffix, BACKUP_SUFFIX)) {
 		args[ac++] = "--suffix";
 		args[ac++] = backup_suffix;

rsync.yo

@@ -273,6 +273,7 @@ verb(
      --progress              show progress during transfer
      --log-format=FORMAT     log file transfers using specified format
      --password-file=FILE    get password from FILE
+     --bwlimit=KBPS          limit I/O bandwidth, KBytes per second
  -h, --help                  show this help screen
 )
 
@@ -643,6 +644,14 @@ transport, not when using a remote shell as the transport. The file
 must not be world readable. It should contain just the password as a
 single line.
 
+dit(bf(--bwlimit=KBPS)) This option allows you to specify a maximum
+transfer rate in kilobytes per second. This option is most effective when
+using rsync with large files (several megabytes and up). Due to the nature
+of rsync transfers, blocks of data are sent, then if rsync determines the
+transfer was too fast, it will wait before sending the next data block. The
+result is an average transfer rate equalling the specified limit. A value
+of zero specifies no limit.
+
 enddit()
 
 manpagesection(EXCLUDE PATTERNS)