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Subject[PATCH v3 06/20] Input: evdev - Add the events() callback
Date
By sending a full frame of events at the same time, the irqsoff
latency at heavy load is brought down from 200 us to 100 us.

Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
---
drivers/input/evdev.c | 68 +++++++++++++++++++++++++++++++++++----------------
1 file changed, 47 insertions(+), 21 deletions(-)
diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
index a0692c5..118d030 100644
--- a/drivers/input/evdev.c
+++ b/drivers/input/evdev.c
@@ -54,16 +54,9 @@ struct evdev_client {
static struct evdev *evdev_table[EVDEV_MINORS];
static DEFINE_MUTEX(evdev_table_mutex);

-static void evdev_pass_event(struct evdev_client *client,
- struct input_event *event,
- ktime_t mono, ktime_t real)
+static void __pass_event(struct evdev_client *client,
+ const struct input_event *event)
{
- event->time = ktime_to_timeval(client->clkid == CLOCK_MONOTONIC ?
- mono : real);
-
- /* Interrupts are disabled, just acquire the lock. */
- spin_lock(&client->buffer_lock);
-
client->buffer[client->head++] = *event;
client->head &= client->bufsize - 1;

@@ -86,42 +79,74 @@ static void evdev_pass_event(struct evdev_client *client,
client->packet_head = client->head;
kill_fasync(&client->fasync, SIGIO, POLL_IN);
}
+}
+
+static void evdev_pass_values(struct evdev_client *client,
+ const struct input_value *vals, unsigned int count,
+ ktime_t mono, ktime_t real)
+{
+ struct evdev *evdev = client->evdev;
+ const struct input_value *v;
+ struct input_event event;
+ bool wakeup = false;
+
+ event.time = ktime_to_timeval(client->clkid == CLOCK_MONOTONIC ?
+ mono : real);
+
+ /* Interrupts are disabled, just acquire the lock. */
+ spin_lock(&client->buffer_lock);
+
+ for (v = vals; v != vals + count; v++) {
+ event.type = v->type;
+ event.code = v->code;
+ event.value = v->value;
+ __pass_event(client, &event);
+ if (v->type == EV_SYN && v->code == SYN_REPORT)
+ wakeup = true;
+ }

spin_unlock(&client->buffer_lock);
+
+ if (wakeup)
+ wake_up_interruptible(&evdev->wait);
}

/*
- * Pass incoming event to all connected clients.
+ * Pass incoming events to all connected clients.
*/
-static void evdev_event(struct input_handle *handle,
- unsigned int type, unsigned int code, int value)
+static void evdev_events(struct input_handle *handle,
+ const struct input_value *vals, unsigned int count)
{
struct evdev *evdev = handle->private;
struct evdev_client *client;
- struct input_event event;
ktime_t time_mono, time_real;

time_mono = ktime_get();
time_real = ktime_sub(time_mono, ktime_get_monotonic_offset());

- event.type = type;
- event.code = code;
- event.value = value;
-
rcu_read_lock();

client = rcu_dereference(evdev->grab);

if (client)
- evdev_pass_event(client, &event, time_mono, time_real);
+ evdev_pass_values(client, vals, count, time_mono, time_real);
else
list_for_each_entry_rcu(client, &evdev->client_list, node)
- evdev_pass_event(client, &event, time_mono, time_real);
+ evdev_pass_values(client, vals, count,
+ time_mono, time_real);

rcu_read_unlock();
+}

- if (type == EV_SYN && code == SYN_REPORT)
- wake_up_interruptible(&evdev->wait);
+/*
+ * Pass incoming event to all connected clients.
+ */
+static void evdev_event(struct input_handle *handle,
+ unsigned int type, unsigned int code, int value)
+{
+ struct input_value vals[] = { { type, code, value } };
+
+ evdev_events(handle, vals, 1);
}

static int evdev_fasync(int fd, struct file *file, int on)
@@ -1050,6 +1075,7 @@ MODULE_DEVICE_TABLE(input, evdev_ids);

static struct input_handler evdev_handler = {
.event = evdev_event,
+ .events = evdev_events,
.connect = evdev_connect,
.disconnect = evdev_disconnect,
.fops = &evdev_fops,
--
1.7.12


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