disadvantages of large interface txqueuelen

m4rtin · 10-23-2011, 01:01 PM

One is able to change the length(amount of memory) of the interface transmit buffer using the:

Code:

ifconfig eth0 txqueuelen <length>

Default value under my Debian(2.6.32-5-amd64) is 1000. What does this 1000 mean? Is it 1000 packages or 1000 bytes or something else?

In addition, are there any disadvantages if one sets the txqueue length higher than needed other than wasted memory?

baldy3105 · 10-24-2011, 10:08 AM

That would be 1000 packets. 1000 bytes is not much of a buffer is it? The only downside to increasing queue lengths other than using up memory, is that as the queue can become longer so can the latency experienced by packets in the queue. Its really application dependant wheather this is a good thing or not. Big FTP sessions prefer data to be held in the queue in the event of congestion so it doesn't have to be resent. Voip on the other hand prefers that packets that are more than a tiy bit late get dropped as they become useless anyway.