V4L/DVB (7699): pvrusb2: Implement statistics for USB I/O performance / tracking

Implement a mechanism in the pvrusb2 driver for gathering statistics
on the stream buffering, including bytes transferred, buffers handled,
buffers in flight, etc.  This is useful for debugging certain classes
of streaming issues and for determining if the buffer pool size is
generally correct for the driver.

Signed-off-by: Mike Isely <isely@pobox.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

1 files changed, 30 insertions, 0 deletions

diff --git a/drivers/media/video/pvrusb2/pvrusb2-io.c b/drivers/media/video/pvrusb2/pvrusb2-io.c
index a9889ff96ecc..7aff8b720064 100644
--- a/drivers/media/video/pvrusb2/pvrusb2-io.c
+++ b/drivers/media/video/pvrusb2/pvrusb2-io.c
@@ -80,6 +80,10 @@ struct pvr2_stream {
         /* Tracking state for tolerating errors */
         unsigned int fail_count;
         unsigned int fail_tolerance;
+
+        unsigned int buffers_processed;
+        unsigned int buffers_failed;
+        unsigned int bytes_processed;
 };
 
 struct pvr2_buffer {
@@ -446,6 +450,8 @@ static void buffer_complete(struct urb *urb)
             (urb->status == -ENOENT) ||
             (urb->status == -ECONNRESET) ||
             (urb->status == -ESHUTDOWN)) {
+                (sp->buffers_processed)++;
+                sp->bytes_processed += urb->actual_length;
                 bp->used_count = urb->actual_length;
                 if (sp->fail_count) {
                         pvr2_trace(PVR2_TRACE_TOLERANCE,
@@ -457,11 +463,13 @@ static void buffer_complete(struct urb *urb)
                 // We can tolerate this error, because we're below the
                 // threshold...
                 (sp->fail_count)++;
+                (sp->buffers_failed)++;
                 pvr2_trace(PVR2_TRACE_TOLERANCE,
                            "stream %p ignoring error %d"
                            " - fail count increased to %u",
                            sp,urb->status,sp->fail_count);
         } else {
+                (sp->buffers_failed)++;
                 bp->status = urb->status;
         }
         spin_unlock_irqrestore(&sp->list_lock,irq_flags);
@@ -515,6 +523,28 @@ void pvr2_stream_set_callback(struct pvr2_stream *sp,
         } while(0); mutex_unlock(&sp->mutex);
 }
 
+void pvr2_stream_get_stats(struct pvr2_stream *sp,
+                           struct pvr2_stream_stats *stats,
+                           int zero_counts)
+{
+        unsigned long irq_flags;
+        spin_lock_irqsave(&sp->list_lock,irq_flags);
+        if (stats) {
+                stats->buffers_in_queue = sp->q_count;
+                stats->buffers_in_idle = sp->i_count;
+                stats->buffers_in_ready = sp->r_count;
+                stats->buffers_processed = sp->buffers_processed;
+                stats->buffers_failed = sp->buffers_failed;
+                stats->bytes_processed = sp->bytes_processed;
+        }
+        if (zero_counts) {
+                sp->buffers_processed = 0;
+                sp->buffers_failed = 0;
+                sp->bytes_processed = 0;
+        }
+        spin_unlock_irqrestore(&sp->list_lock,irq_flags);
+}
+
 /* Query / set the nominal buffer count */
 int pvr2_stream_get_buffer_count(struct pvr2_stream *sp)
 {