redonkable/remarkable-linux
redonkable/remarkable-linux
1
0
Fork 0
Code Releases Activity

tty: Only wakeup the line discipline idle queue when queue is active

Browse source 
Before waking up the tty line discipline idle queue first check if the queue is
active (non empty). This prevents unnecessary entering the critical section in
the wake_up() function and therefore avoid needless scheduling overhead on a
PREEMPT_RT system caused by two processes being in the same critical section.

Signed-off-by: Ivo Sieben <meltedpianoman@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ivo Sieben 2012-12-18 15:48:50 +01:00 committed by Greg Kroah-Hartman
parent b342dd512f
commit bd5d7ce9af
1 changed files with 3 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

4
drivers/tty/tty_ldisc.c
View file

@ -64,7 +64,9 @@ static void put_ldisc(struct tty_ldisc *ld)
return;
}
raw_spin_unlock_irqrestore(&tty_ldisc_lock, flags);
wake_up(&ld->wq_idle);
if (waitqueue_active(&ld->wq_idle))
wake_up(&ld->wq_idle);
}
/**