From 80550dad577bec47979ff6057dac92f9c7503a37 Mon Sep 17 00:00:00 2001 From: "kfraser@localhost.localdomain" Date: Fri, 29 Sep 2006 11:16:52 +0100 Subject: [PATCH] [BLKTAP] Remove unnecessary timeout from tapdisk select() call. tapdisk was using a 1msec select() timeout in its main event loop. On timeout, the loop does nothing except repeat, so the timeout achieves nothing; worse, on a machine with HZ set to less than 1000, a msec timeout returns immediately, sending tapdisk into a 100%-CPU- utilisation loop. Simply remove the timeout entirely; everything still works fine, and much more efficiently when idle. Signed-off-by: Stephen Tweedie --- tools/blktap/drivers/tapdisk.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) diff --git a/tools/blktap/drivers/tapdisk.c b/tools/blktap/drivers/tapdisk.c index 3190a2b219..7c88027eb3 100644 --- a/tools/blktap/drivers/tapdisk.c +++ b/tools/blktap/drivers/tapdisk.c @@ -271,7 +271,6 @@ static int read_msg(char *buf) int length, len, msglen, tap_fd, *io_fd; char *ptr, *path; image_t *img; - struct timeval timeout; msg_hdr_t *msg; msg_newdev_t *msg_dev; msg_pid_t *msg_pid; @@ -579,8 +578,7 @@ int main(int argc, char *argv[]) { int len, msglen, ret; char *p, *buf; - fd_set readfds, writefds; - struct timeval timeout; + fd_set readfds, writefds; fd_list_entry_t *ptr; struct tap_disk *drv; struct td_state *s; @@ -622,12 +620,9 @@ int main(int argc, char *argv[]) /*Set all tap fds*/ LOCAL_FD_SET(&readfds); - timeout.tv_sec = 0; - timeout.tv_usec = 1000; - /*Wait for incoming messages*/ ret = select(maxfds + 1, &readfds, (fd_set *) 0, - (fd_set *) 0, &timeout); + (fd_set *) 0, NULL); if (ret > 0) { -- 2.30.2