[syslog-ng]performance test questions

[Roberto Nibali]

> Both TCP and UDP use the same code to send messages in 1.5.x and as it seems
> syslog-ng piggybacks messages together when writing messages. This is
> correct for TCP but incorrect for UDP.

Yes.

> The culprit is libol/src/pkt_buffer.c which uses stream based buffering in
> the 0.3 branch while it used a packet based one in 0.2

I see.

> As there are more than one message in a single UDP packet the packet can
> grow bigger than your MTU, thus packet fragmentation is done. 

Exactly, although this should influence the loss too much, IMHO.

> Both can increase message loss (more than one message in a single packet,
> fragmentation) thus this is definitely a bug. 
> I'll look into fixing this.

Thanks.

>>Another question: Why is there no message sent when a buffer reaches its 
>>maximum size? This would help debugging and tuning a lot IMHO. Sorry if 
>>this has been discussed before.
>>
>
> Because this message itself would fill your buffers. Instead syslog-ng

Doh (slaps forehead), Of course.

> reports the number of dropped messages in a separate message sent once every
> ten minutes (default).

Call me stupid but (assuming you mean the STATS part):

ratz@zar:~/down/log > find . -name "*.[ch]" -exec grep -n dropped_pkts /dev/null 
{} \;
./libol-0.3.8/src/pkt_buffer.h:30:int pktbuf_dropped_pkts;
./syslog-ng-1.5.25/src/main.c:138:	notice("STATS: dropped %i\n", 
pktbuf_dropped_pkts);
./syslog-ng-1.5.25/src/main.c:139:	pktbuf_dropped_pkts = 0;
ratz@zar:~/down/log >

What else then 0 should this code print? At least I've found the hardcoded 
timeout in libol/src/io.c. :)

Thanks for your time,
Roberto Nibali, ratz
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