tuning for high connection rates

Bill Moran wmoran at collaborativefusion.com
Tue Dec 4 17:01:38 PST 2007

Philipp Wuensche <cryx-freebsd at h3q.com> wrote:
> Hi,
> we are running a FreeBSD 7-BETA4 with SCHED_4BSD on a Intel Core2Dual
> E6600 2.4GHz system for our bittorrent Opentracker.
> The system handles about 20Kpps (18Mbit/s) incoming and 15kpps (22
> Mbit/s) outgoing traffic serving 4000 connections/sec using TCP. The
> connections are very short-living, all answered within one packet.
> You can find the system stats at
> http://outpost.h3q.com/stalker/munin/opentracker/opentracker.html
> We are now running into some limits at peak time, system is up to 100%
> and em0 takes about 80% on one CPU while the Opentracker software only
> takes 10-15% CPU. The system is still responsible and answers all the
> requests, but we are worried what will happen if the tracker grows at
> the current rate.
> Currently we are out of ideas for tuning, so we kindly ask for ideas on
> tuning the system to bring down the CPU usage from the em and the system
> CPU usage. We tried tuning the em int_delay and abs_int_delay but
> without success.

Enable polling on the interface and see if that helps.  See man polling.

Bill Moran
Collaborative Fusion Inc.

wmoran at collaborativefusion.com
Phone: 412-422-3463x4023

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