From mboxrd@z Thu Jan 1 00:00:00 1970 From: One Thousand Gnomes Subject: Re: [PATCH tty-next 6/7] n_tty: Only perform wakeups for waiters Date: Sun, 24 Nov 2013 00:23:24 +0000 Message-ID: <20131124002324.2fe609d6@alan.etchedpixels.co.uk> References: <1385135965-4235-1-git-send-email-peter@hurleysoftware.com> <1385135965-4235-7-git-send-email-peter@hurleysoftware.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Received: from lxorguk.ukuu.org.uk ([81.2.110.251]:41052 "EHLO lxorguk.ukuu.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756448Ab3KXAXb (ORCPT ); Sat, 23 Nov 2013 19:23:31 -0500 In-Reply-To: <1385135965-4235-7-git-send-email-peter@hurleysoftware.com> Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: Peter Hurley Cc: Greg Kroah-Hartman , Jiri Slaby , linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org On Fri, 22 Nov 2013 10:59:24 -0500 Peter Hurley wrote: > Only wakeup the _waiting_ reader, polls and/or writer(s). > > Signed-off-by: Peter Hurley > --- > drivers/tty/n_tty.c | 18 ++++++++++++------ > 1 file changed, 12 insertions(+), 6 deletions(-) > > diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c > index 8f2356e..aae28a6 100644 > --- a/drivers/tty/n_tty.c > +++ b/drivers/tty/n_tty.c > @@ -275,7 +275,8 @@ static void n_tty_check_unthrottle(struct tty_struct *tty) > return; > n_tty_set_room(tty); > n_tty_write_wakeup(tty->link); > - wake_up_interruptible_poll(&tty->link->write_wait, POLLOUT); > + if (waitqueue_active(&tty->link->write_wait)) > + wake_up_interruptible_poll(&tty->link->write_wait, POLLOUT); Does this actually microbenchmark faster ? Alan