On Thu, 2007-06-21 at 23:22 +0200, Christian Benvenuti wrote: > Hi Mark, > > >Hi, > > > >What exactly are the "tokens"? > > > >I thought each token allowed the sending of one byte, that tokens are > >stored in a bucket that can hold a max of "burst" tokens, and that this > >bucket is filled with tokens at "rate". > > > >But theory does not seem to explain the "tc -s .." output in the > >examples below. And I can't figure out why or how... > > Tokens normally represent the number of bytes the token bucket algorithm has > accumulated. However, the numbers you see with tokens/ctokens are not expressed > in bytes: they are expressed in units of time whose size is an approximation of > 1 microsecond (how close a unit of time is to 1 microsecond depends on the kernel > config). > For example, the value of "tokens" that you see soon after configuring the > HTB qdisc (and supposing no traffic has gone through the qdisc yet) is the > number of pseudo microseconds that are necessary to transmit "burst" bytes > at the rate "rate" configured on the class. Thanks for the explanation. I understand, the tokens as displayed are based on implementation details rather then pure concept/theory. Guess it also explains why the number of tokens can be negative. If a (c)bursts causes a class to exceed it's configured rate it will take some time (that many pseudo microseconds) for the rate to drop back to the configured rate. Right? > It may look more complex that what it actually is. Just think of it as > the number of (pseudo) microseconds the class can transmit at rate "rate" > without terminating its tokens. > The last sentence above should answer your questions in the second part of > the email too. Indeed. Thanks, Mark. > Regards > /Christian > [ http://benve.info ] > > > >#tc qdisc del dev eth0 root > >#tc qdisc add dev eth0 root handle 1: htb default 1 > >#tc class add dev eth0 parent 1:0 classid 1:1 htb rate 2mbit > >#tc -s -d class show dev eth0 > >class htb 1:1 root prio 0 quantum 25000 rate 2000Kbit ceil 2000Kbit burst 2599b/8 mpu 0b overhead 0b cburst 2599b/8 mpu 0b overhead 0b level 0 > > Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) > > rate 0bit 0pps backlog 0b 0p requeues 0 > > lended: 0 borrowed: 0 giants: 0 > > tokens: 10649 ctokens: 10649 > > > >#tc qdisc del dev eth0 root > >#tc qdisc add dev eth0 root handle 1: htb default 1 > >#tc class add dev eth0 parent 1:0 classid 1:1 htb rate 1mbit > >#tc -s -d class show dev eth0 > >class htb 1:1 root prio 0 quantum 12500 rate 1000Kbit ceil 1000Kbit burst 2099b/8 mpu 0b overhead 0b cburst 2099b/8 mpu 0b overhead 0b level 0 > > Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) > > rate 0bit 0pps backlog 0b 0p requeues 0 > > lended: 0 borrowed: 0 giants: 0 > > tokens: 17203 ctokens: 17203 > > > >Why do the amount of tokens go UP if the configured rate (and burst) is > >lower? > >(The commands where run from a script so these amounts of tokens > >available right after the creation of the class.) > > > >If I set the rate to 9mbit the amount of tokens is always lower then the > >burst size. Wouldn't that mean that there are always too few tokens > >available to actually burst the "burst" amount of data? > > > >Regards, > >Mark. > > _______________________________________________ LARTC mailing list LARTC@xxxxxxxxxxxxxxx http://mailman.ds9a.nl/cgi-bin/mailman/listinfo/lartc
