Project

General

Profile

Actions

Bug #5552

open

no overall limit of paging requests at BSC level

Added by laforge about 2 months ago. Updated 17 days ago.

Status:
New
Priority:
Normal
Assignee:
Category:
A interface
Target version:
-
Start date:
05/06/2022
Due date:
% Done:

0%

Spec Reference:

Description

It seems we don't have any maximum queue depth for paging requests from the MSC. I've created a TTCN3 test that sends 100 new paging requests per second, and I can see the per-BTS paging queue grow to > 4000 entries, associated with the BSC spending all the CPU cycles it can get in _paging_request

 Paging: 4004 pending requests, 16 free slots 

I think there shold be some upper limit for the per-BTS paging queue at the BSC.


Related issues

Related to OsmoBSC - Bug #5553: dynamic T3113 has no reasonable upper boundResolvedpespin05/06/2022

Actions
Actions #1

Updated by pespin about 2 months ago

It may make sense, once reached the threshold of the maximum amount of allowed requests, to try to drop one of the in-retransmission-state requests in the queue, and accept the new one.

Actions #2

Updated by laforge about 2 months ago

  • Related to Bug #5553: dynamic T3113 has no reasonable upper bound added
Actions #3

Updated by pespin 17 days ago

Maximum paging length is already implemented since the last bunch of osmo-bsc paging improvements. See paging.c _paging_request():

#define MAX_TX_DELAY_TIME_SEC 60
[...]
    /* don't try to queue more requests than we can realistically handle within MAX_TX_DELAY_TIME_SEC seconds */
    if (paging_pending_requests_nr(bts) > paging_estimate_available_slots(bts, MAX_TX_DELAY_TIME_SEC)) {
        rate_ctr_inc(rate_ctr_group_get_ctr(bts->bts_ctrs, BTS_CTR_PAGING_OVERLOAD));
        return -ENOSPC;
    }

Some stuff we may want to improve here:
  • Make "MAX_TX_DELAY_TIME_SEC 60" configurable through VTY. This may be useful to configure it so that it matches some paging timeout config at the MSC?
  • When the queue is full, instead of dropping it, remove the first non-initial (retrans) entry from the list, then add this new paging req.
Actions

Also available in: Atom PDF

Add picture from clipboard (Maximum size: 48.8 MB)