On Fri, 22 Jul 2005 09:55:25 +0200 "Christian Konecny (VI/SEA)" <christian.konecny@xxxxxxxxxxxx> wrote: > Hi there! > > I am working a lot with VoIP in my company, so I thought to use linux > bridge functionality together with tc to emulate delay, jitter, > packet loss, duplication, reordering etc. for testing purposes in our > lab against our VoIP products. I just recognized, that a basic bridge > just with it's minumum configuration of 2 network interfaces creates > latency of approx. 5ms on very low traffic. This seems to be > independent on CPU speed. I tried on 2 GHz PC while having just > 64kBit traffic with packet size of about 300bytes. I am using Knoppix > 3.82 which is actually a debian Live-CD Linux, Kernel 2.6.11. For > some reason they put iproute2 041019 on this distro, which is > intended to be used for kernel 2.6.9. I am aware of remastering the > CD, but have to check if it is possible to recompile the kernel for > the remaster. > > back to my question: where does this latency come from? > "top" shows almost no load while the bridge is handling traffic, so > how come? is there some timer-granularity which can be set in the > kernel, is the latency normal, or what could cause it else? > > Thank you very much in advance! > > /Christian > What hardware, and setup scripts? If you are using netem then it can add latency. The amount depends on the requested delay and the HZ value of the kernel and the choice of PSCHED_CLOCK_SOURCE in the kernel configuration. _______________________________________________ LARTC mailing list LARTC@xxxxxxxxxxxxxxx http://mailman.ds9a.nl/cgi-bin/mailman/listinfo/lartc
