[media] saa7164: measure via histograms various irq and queue latencies

saa7164: measure via histograms various irq and queue latencies
Attempting to determine where buffering issues under high load are due
to highly latent irq or work queue handling.

Signed-off-by: Steven Toth <stoth@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/drivers/media/video/saa7164/saa7164-encoder.c b/drivers/media/video/saa7164/saa7164-encoder.c
index e340a6e39dfc..5f73ceded31b 100644
--- a/drivers/media/video/saa7164/saa7164-encoder.c
+++ b/drivers/media/video/saa7164/saa7164-encoder.c
@@ -1030,6 +1030,14 @@ static ssize_t fops_read(struct file *file, char __user *buffer,
         int rem, cnt;
         u8 *p;
 
+        port->last_read_msecs_diff = port->last_read_msecs;
+        port->last_read_msecs = jiffies_to_msecs(jiffies);
+        port->last_read_msecs_diff = port->last_read_msecs -
+                port->last_read_msecs_diff;
+
+        saa7164_histogram_update(&port->read_interval,
+                port->last_read_msecs_diff);
+
         if (*pos)
                 return -ESPIPE;
 
@@ -1114,6 +1122,14 @@ static unsigned int fops_poll(struct file *file, poll_table *wait)
         struct saa7164_user_buffer *ubuf;
         unsigned int mask = 0;
 
+        port->last_poll_msecs_diff = port->last_poll_msecs;
+        port->last_poll_msecs = jiffies_to_msecs(jiffies);
+        port->last_poll_msecs_diff = port->last_poll_msecs -
+                port->last_poll_msecs_diff;
+
+        saa7164_histogram_update(&port->poll_interval,
+                port->last_poll_msecs_diff);
+
         if (!video_is_registered(port->v4l_device)) {
                 return -EIO;
         }