[OLSR-users] CPU load

[Sven-Ola Tuecke]

Hi Thomas,

some couple of minutes ago I rechecked with one of my wrt54g routers. The 
acutal CPU load was between 7-20% which is fine. I disabled the one and only 
dyn-gw plugin, but there was no change in CPU load. Of course, I run with 
"-d 0".

Regards, Sven-Ola

"Thomas Lopatic" <(spam-protected)> schrieb im Newsbeitrag 
news:(spam-protected)
> Hi there,
>
> some quick thoughts on the CPU load problem.
>
> * What happens if debug output is switched off, i.e. the debug level is 
> set to 0? On my old Pentium 233 olsrd was not usable due to CPU load even 
> in a pretty small network with the debug level set to anything beyond 1.
>
> * It would be interesting which parts of olsrd cause the high load. If 
> increasing the poll interval makes much of a difference, then it's the 
> periodically executed tasks like expelling timed out nodes from the 
> internal data structures. If increasing the HELLO intervals of all 
> surrounding nodes makes much of a difference, then it's the processing of 
> incoming packets.
>
> * I've thought through the linear list thing again. True, there are more 
> efficient data structures and I have a gut feeling that we could save a 
> few lookups by caching the results of previous lookups. But then again, 
> the performance problems start already at fifty nodes, which shouldn't be 
> a problem for the existing data structures. (For potentially larger sets 
> we use a hash function to distribute the set elements over a number of 
> linear lists.)
>
> To sum up, I don't have any idea why we have such a high CPU load. :-) So, 
> let's find out. I guess that the easiest change would be to lower the 
> debug level on a single node and see what this does to the CPU load on 
> this node. The next change could then be to increase the poll interval 
> length on the node and see whether this makes any difference.
>
> If this still doesn't make any difference, we should come up with a 
> profiling version of olsrd. Has anyone ever used the profiling features of 
> GCC? Are they supported by the cross-compiler? I guess that this would 
> give us a good idea in which functions olsrd spends most of its CPU 
> cycles.
>
> -Thomas
>
>
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