On SMP systems, it is possible for an evdev client blocked on poll() to wake up and read events from the evdev ring buffer at the same rate as they are enqueued. This can result in high CPU usage, particularly for MT devices, because the client ends up reading events one at a time instead of reading complete packets. This patch ensures that the client only wakes from poll() when a complete packet is ready to be read. Signed-off-by: jeffbrown@xxxxxxxxxxx --- drivers/input/evdev.c | 5 +++-- 1 files changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c index 203ed70..7b6770d 100644 --- a/drivers/input/evdev.c +++ b/drivers/input/evdev.c @@ -73,7 +73,7 @@ static void evdev_pass_event(struct evdev_client *client, } spin_unlock(&client->buffer_lock); - if (event->type == EV_SYN) + if (event->type == EV_SYN && event->code != SYN_MT_REPORT) kill_fasync(&client->fasync, SIGIO, POLL_IN); } @@ -103,7 +103,8 @@ static void evdev_event(struct input_handle *handle, rcu_read_unlock(); - wake_up_interruptible(&evdev->wait); + if (type == EV_SYN && code != SYN_MT_REPORT) + wake_up_interruptible(&evdev->wait); } static int evdev_fasync(int fd, struct file *file, int on) -- 1.7.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
