[svn-commits] rmeyerriecks: linux/trunk r10726 - /linux/trunk/include/dahdi/kernel.h

[SVN commits to the Digium repositories]

Author: rmeyerriecks
Date: Thu Oct  4 15:24:17 2012
New Revision: 10726

URL: http://svnview.digium.com/svn/dahdi?view=rev&rev=10726
Log:
dahdi: Increase the number of conference buffers to eight.

When DAHDI is bridging channels between two different cards, or a user is trying
to record from a channel on a card that is not using the same timing source as
the master span, it is possible to miss audio.

For example, given the following scenario:

<T1 Span> <---> <ISDN CARD> <---> <ANALOG CARD> <---> <local handset>

If DAHDI was set to natively bridge the call from the T1 span to the local
handset it is possible that system conditions could result in one of the cards
servicing their interrupt three times before the other card has a chance to.
Since there are currently only two conference buffers to pass audio between the
cards, one chunk (1ms) of audio will be dropped since the card servicing it's
interrupt more frequently will run out of space to copy audio for the other card
and will have emptied the audio buffer from the other card.

Increasing the number of conference buffers to eight greatly reduces the
probability of audio from being dropped under these conditions at cost of an
additional 72 (32-bit) or 96 (64-bit) bytes per DAHDI channel.

Internal-Issue-ID: DAHLIN-159, DAHDI-976
Signed-off-by: Shaun Ruffell <sruffell at digium.com>
Signed-off-by: Russ Meyerriecks <rmeyerriecks at digium.com>

Modified:
    linux/trunk/include/dahdi/kernel.h

Modified: linux/trunk/include/dahdi/kernel.h
URL: http://svnview.digium.com/svn/dahdi/linux/trunk/include/dahdi/kernel.h?view=diff&rev=10726&r1=10725&r2=10726
==============================================================================
--- linux/trunk/include/dahdi/kernel.h (original)
+++ linux/trunk/include/dahdi/kernel.h Thu Oct  4 15:24:17 2012
@@ -107,7 +107,7 @@
 #define DAHDI_MIN_CHUNKSIZE	 DAHDI_CHUNKSIZE
 #define DAHDI_DEFAULT_CHUNKSIZE	 DAHDI_CHUNKSIZE
 #define DAHDI_MAX_CHUNKSIZE 	 DAHDI_CHUNKSIZE
-#define DAHDI_CB_SIZE		 2
+#define DAHDI_CB_SIZE		 (1 << 3)
 
 /* DAHDI operates at 8Khz by default */
 #define DAHDI_MS_TO_SAMPLES(ms) ((ms) * 8)