tuning for high connection rates

Jin Guojun jin at george.lbl.gov
Tue Dec 4 18:59:48 PST 2007

Philipp Wuensche <cryx-freebsd at h3q.com> wrote:

>>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
>>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.
Is there some data for the context switch time? It may tell something.


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