From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1LWivJ-0005il-Az for qemu-devel@nongnu.org; Mon, 09 Feb 2009 22:04:33 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1LWivH-0005iB-Ly for qemu-devel@nongnu.org; Mon, 09 Feb 2009 22:04:32 -0500 Received: from [199.232.76.173] (port=46515 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1LWivH-0005ht-Gg for qemu-devel@nongnu.org; Mon, 09 Feb 2009 22:04:31 -0500 Received: from mx2.redhat.com ([66.187.237.31]:40238) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1LWivG-0004Ah-Lr for qemu-devel@nongnu.org; Mon, 09 Feb 2009 22:04:30 -0500 Message-ID: <4990EEB9.8080208@redhat.com> Date: Tue, 10 Feb 2009 05:04:25 +0200 From: Uri Lublin MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] [RESEND] [PATCH 1/2] migrate.c: migrate_fd_put_buffer(): Do not busyloop: stop writing if EWOULDBLOCK Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Uri Lublin Theoretically the migration code is non-blocking, designed for live migration. Practically migrate_fd_put_buffer busy-loops trying to write. That's since on many machines EWOULDBLOCK==EAGAIN (e.g. look in /include/asm-generic/errno.h). Busy looping is much worse then blocking (in case a write actually blocks). Fixed by removing "(s->get_error(s)) == EWOULDBLOCK)" from the while condition. Signed-off-by: Uri Lublin --- migration.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/migration.c b/migration.c index 0ef777a..e8bafa6 100644 --- a/migration.c +++ b/migration.c @@ -168,7 +168,7 @@ ssize_t migrate_fd_put_buffer(void *opaque, const void *data, size_t size) do { ret = s->write(s, data, size); - } while (ret == -1 && ((s->get_error(s)) == EINTR || (s->get_error(s)) == EWOULDBLOCK)); + } while (ret == -1 && s->get_error(s) == EINTR); if (ret == -1) ret = -(s->get_error(s)); -- 1.6.0.6