High CPU load

[Jonathan Stewart]

Hi Simone,

I would guess that syslog has better buffering and load handling; so I
would try logging only to syslog--this should halve the load caused by
verbose logging.

Speaking of verbose, I've looked at BIRD logs, and I see lines like this:
 Route A received by peer Y
 Route A announced to peer X
 Route A announced to peer Y

So, you multiply the number of roues by the number of peers:
 (100 000 x 152)
 =   15 200 000

But you're logging it twice (bird and syslog), so it's now 30 million lines
of logs, to be written, just to bring up the peer. At 80 characters per
line, would be 2.3 GB data to disk.

This could cause serious load on a system with a modest HDD.

It's also possible that each line causes a logging process which takes CPU
time--do it 30 million times and the CPU time needed becomes large.

What kind of CPU or disk do you have?  Can you share?

Maybe the solution is to buy more CPU and disk performance.

On Wed, Apr 8, 2015 at 5:18 AM, Simone Morandini <
simone.morandini at mix-it.net> wrote:

> Hello list,
>
> we are running BIRD on our IXP peering platform with no problems since
> quite a while now.
> We need to activate a new peer which is expected to announce a
> considerable amount of prefixes (~100k), and the first try resulted in
> having nearly 100% cpu load, ~60-70% for BIRD and the remaining for syslog.
> The machine was hardly manageable, so after a few minutes we had to disable
> the peer and restart the deamon.
>
> The current settings actually make BIRD log everything:
> log "/var/log/bird.log" all;
> log syslog all;
>
> so I guess we could start by modifying it: any advice on this?
> Would you suggest something more, in order to avoid having again a high
> cpu load?
>
> Thanks in advance,
> Simone.
>



-- 
     Jonathan
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