On Fri, Jun 4, 2010 at 6:57 AM, Luigi Rizzo <[email protected]> wrote: > On Fri, Jun 04, 2010 at 01:19:32AM -0700, bored to death wrote: >> thank you luigi for your reply, it helped. >> >> i changed the hz parameter to 1000 and then 4000 and then 8000 in my >> /boot/loader.conf. the result got much better. >> i configured my system as a router and i send 1GB traffic rate passing by it >> and set an 800MBytes bandwidth limit on input traffic with dummynet. >> this was the result: >> with hz=1 (default) between 200MBytes/s and 300MBytes/s >> with hz=1000 between 200MBytes/s and 300MBytes/s >> with hz=4000 between 350MBytes/s and 450MBytes/s >> with hz=8000 between 250MBytes/s and 550MBytes/s >> >> the maximum traffic rate is got so much better, but 2 problems still remain: >> 1- the maximum rate is still not high enough. >> 2- the rate variation range is high (250-550) and it's not a steady enough. >> >> i've also tried setting different "queue" and "burst" values for the pipe. >> the result is a little better when i set "queue" to a value between 80MBytes >> and 90MBytes and "burst" to a big number. >> >> any other ideas? >> > > HZ=1000 is the default, for the records. > Setting the burst size should have no practical effects, > whereas setting the queue size e.g. > o > ipfw pipe 10 config bw 800Mbit/s queue 200kbytes > > should help a lot, but check your configuration with 'ipfw pipe show' > because if you supply an invalid parameter ipfw silently uses > a default or something different. > As an example, you said you used 80-90 Mbytes but the max queue > size is 100 packets or 1023Kbytes and larger values do not produce > the desired effect. > > As a rule of thumb, to make sure that drops are not caused > by short queues, you should set the queue size to 1/HZ seconds > worth of data -- at HZ=1000 and 1Gbit/s this means 128Kbytes. > Note that after the dummynet queue, there might be some other > queue that saturates. As an example, when using the box as a router, > packets go in bursts to the output interface, and the burst can > be as large as 1500 packets per tick on a fully saturated Gig-E > (the interface's queue ranges normally between 128 and 1024 slots). > The only fix for this is probably using higher values of HZ. > > chers > luigi
Thanks for the explanation Luigi, this is bound to help others in regard to queue configuration. -Brandon _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-ipfw To unsubscribe, send any mail to "[email protected]"
