Change in osmo-bts[master]: bts_agch_enqueue: Decrease queue len hard_limit from 1000 to 50

[Pau Espin Pedrol]

Pau Espin Pedrol has uploaded this change for review. ( https://gerrit.osmocom.org/9513


Change subject: bts_agch_enqueue: Decrease queue len hard_limit from 1000 to 50
......................................................................

bts_agch_enqueue: Decrease queue len hard_limit from 1000 to 50

In a prod setup, complete channel saturation at the bsc was detected,
and Immediate Assignments were not being answered by the MS once sent by
the BTS.
Further investigation showed that the BTS was all the time printing
messages like this:
"bts.c:540 AGCH: too many messages in queue, refusing message type 0x3f, length = 1001/10"

So it seems the AGCH queue was becoming incredibly full (1000, hard
limit triggered the log), while acgch_queue.max_length was set to 10.

As a result, most probably the Immediate Assignments being sent to the
MS are super old in time, and the MS doesn't known about them anymore
once they are receivied, so no answer is sent back.

Let's try to avoid that by decreasing the hard limit so we never reach
that big queue_len scenario.

Related: SYS#2695
Change-Id: I272798c959abec123776d2fa8dad5685ec512fbd
---
M src/common/bts.c
1 file changed, 1 insertion(+), 1 deletion(-)



  git pull ssh://gerrit.osmocom.org:29418/osmo-bts refs/changes/13/9513/1

diff --git a/src/common/bts.c b/src/common/bts.c
index 55f4b94..1315a0a 100644
--- a/src/common/bts.c
+++ b/src/common/bts.c
@@ -533,7 +533,7 @@
 
 int bts_agch_enqueue(struct gsm_bts *bts, struct msgb *msg)
 {
-	int hard_limit = 1000;
+	int hard_limit = 50;
 	struct gsm48_imm_ass_rej *imm_ass_cmd = msgb_l3(msg);
 
 	if (bts->agch_queue.length > hard_limit) {

-- 
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Gerrit-Project: osmo-bts
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: I272798c959abec123776d2fa8dad5685ec512fbd
Gerrit-Change-Number: 9513
Gerrit-PatchSet: 1
Gerrit-Owner: Pau Espin Pedrol <pespin at sysmocom.de>
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