Re: [Wireshark-commits] rev 32822: /trunk/epan/dissectors/ /trunk/epan/dissectors/: packet-q708.c

[Gerasimos Dimitriadis <gedimitr () otenet gr>]

Hi,

I did some benchmarking on the performance gains from the switch to 
binary search in the SANC and ISPC arrays, that I want to share with the 
list. The SANC array contains ~900 entries, while the 2 ISPC arrays 
(signalling point and operator names) contain ~5k entries each.

For this experiment, a synthetic capture file of 50000 MTP3/SCCP 
messages was created. Each message is based on the following template, 
with the OPC and DPC being randomly chosen from values existing in the 
ISPC array. This means that the search always leads to a match, but 
since this list contains all PCs currently allocated by the ITU, this is 
going to be the case for actual traffic too.

Message Transfer Part Level 3
    Service information octet
        00.. .... = Network indicator: International network (0x00)
        ..00 .... = Spare: 0x00
        .... 0011 = Service indicator: SCCP (0x03)
    Routing label
        .... .... .... .... ..11 1001 1110 0110 = DPC: 14822
            Signalling Area Network Code (SANC): Chile (7-060)
            Unique Signalling Point Name: ...
            Signalling Point Operator Name: Compania de Telefonos de 
Chile - Mundo S.A.
        .... 1000 0001 1100 00.. .... .... .... = OPC: 8304
            Signalling Area Network Code (SANC): India (Republic of) (4-014)
            Unique Signalling Point Name: ISC Chennai
            Signalling Point Operator Name: M/s Dishnet Wireless Ltd
        0011 .... .... .... .... .... .... .... = Signalling Link 
Selector: 3
Signalling Connection Control Part
    Message Type: Released (0x04)
    Destination Local Reference: 0xffda05
    Source Local Reference: 0x1001df
    Release Cause: End user originated (0x00)
    Pointer to Optional parameter: 0

In each scenario (linear / binary search), tshark -V was run 3 times 
with the output redirected to /dev/null. The averages are provided 
below, showing that the performance improvements are substantial:
Linear Search: real 6.302s - user 5.355s - sys 0.738s
Binary Search: real 4.868s - user 4.004s - sys 0.697s

Regards
Gerasimos

> http://anonsvn.wireshark.org/viewvc/viewvc.cgi?view=rev&revision=32822
>
> User: dimeg
> Date: 2010/05/15 01:14 PM
>
> Log:
>  Use binary search when scanning the SANC and ISPC lists; correct a couple of
>  double entries in the ISPC lists.
>
> Directory: /trunk/epan/dissectors/
>   Changes    Path             Action
>   +9 -7      packet-q708.c    Modified
>
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