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Date: Mon, 04 Jul 2011 02:54:27 +0700
From: Eugene Grosbein <egrosbein@rdtc.ru>
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To: Adrian Minta <gygy@stsnet.ro>
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Cc: freebsd-net@freebsd.org
Subject: Re: FreeBSD 8.2 and MPD5 stability issues - update
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04.07.2011 02:15, Adrian Minta пишет:
> After looking in the mpd log file I found out that this message appear
> when calls are dropped:
> Jul  3 21:21:21 lns mpd: Daemon overloaded, ignoring request.
> Jul  3 21:21:22 lns mpd: Daemon overloaded, ignoring request.
> Jul  3 21:21:23 lns mpd: Daemon overloaded, ignoring request.
> Jul  3 21:21:23 lns mpd: Daemon overloaded, ignoring request.
> Jul  3 21:21:24 lns mpd: Daemon overloaded, ignoring request.
> Jul  3 21:21:24 lns mpd: Daemon overloaded, ignoring request.
> 
> Does anybody knows where this limit is set in mpd5 ?
> 

There is internal queue of messages in the mpd-5.5 with length 8129.
Messages are generated based on various events and enqueued there, then processed.

Mpd uses GRED algorithm to prevent overload: it accepts all new L2TP connections
when queue has 10 or less slots occupied (unprocessed events).

It drops all connections then it has over 60 slots occupied.
In between, it drops new message with probability equal to (q-10)*2 percents
where q is number of occupied queue slots. These constants are hardcoded in its src/ppp.h

Each time it decided to ignore incoming L2TP requests it notes that in the log,
as you have already seen.

Eugene Grosbein