Avoid LCR-Stalling

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Konrad Meier meierk at informatik.uni-freiburg.de
Tue Aug 10 13:56:22 UTC 2010


Dear List,

At the moment I am building a GSM-Network with OpenBSC and three NanoBTS 
at the University of Freiburg. The purpose of this network is teaching 
and research. The Network has an ISDN BRI Interface which allows every 
gsm-phone to be called over a land line telephony number.

We had huge problems with LCR-Stalling in our setup which lead to a 
increasing delay during a call (up to 6-10 seconds...). We could trace 
the problem to lookups in the database hlr.sqlite3. After some time the 
database was about 18MB big and it took some time to perform operations 
in the database.

The quick solution was to copy the database to a RAM-Disk. A RAM-Disk 
can be created like this:
  sudo mount -t tmpfs -o size=300M tmpfs ramdisk

After that, we never had seen stalling anymore.

But this can only be considered as a quick hack because in case of a 
system failure all changes to the database are lost.

Is someone at the moment working on a interface to a better database 
system? Maybe I find some student who can do this.

Regards
  Konrad Meier




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