[ixpmanager] SFLOW Under Reporting?

[Nick Hilliard (INEX)]

Ian Chilton wrote on 27/06/2023 10:18:
> Added `use threads;` and did this 1 line fix:
> 
> -               process_rrd($interval, $matrix, $rrdcached);
> +               threads->create('process_rrd', $interval, $matrix, 
> $rrdcached);
> 
> Bingo!
> 
> We're now doing 736G according to MRTG, the life sflow graphs are 
> reporting 332G, now my new instance in a VM is giving 703G and on bare 
> metal 705G.

That sounds a lot better. In terms of approaches, I was considering a 
straightforward fork, but probably the threads approach is simpler in 
this case. The complete patch would include a change to the default 
timer interval from 60s to 300s, and also to make a copy of $matrix 
before passing to the thread, to ensure that concurrency problems are 
ruled out.

> I still think it's worth re-writing this in Go for performance, which I 
> can look at in the future, but for now that appears to have resolved 
> things.

the performance bottleneck is the rrd/rrdcached flush process, not the 
perl bits.  Rewriting in go won't fix this.

Nick