[LARTC] typo ?

[LARTC] typo ?

[Mihai RUSU]

Hi

While reading the HOWTO (pdf downloaded and printed last night) I have
noticed a little strange thing. In the 9.2.1 chapter, explaining the
pfifo_fast qdisc, it is shown a TOS field mapping table and also it
appears a command line version:

"The last column shows the result of the default priomap. On the
commandline, the default priomap looks like this:
1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1

This means that priority 4, for example, gets mapped to band number 1. The
priomap also allows you to list higher priorities (> 7) which do not
correspond to TOS mappings, but which are set by other means."

The numbers on the command line version are 16, thus I presume its a one
to one corespondation to the table, only that it is completly different. I
dont see any explanation why it is like that. Shouldnt that be:
1,2,1,1,2,2,2,2,0,0,0,0,1,1,1,1 ?

Thanks

----------------------------
Mihai RUSU

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Re: [LARTC] typo ?

[Soulfly]

"Mihai RUSU" wrote

> Hi
>
> While reading the HOWTO (pdf downloaded and printed last night) I have
> noticed a little strange thing. In the 9.2.1 chapter, explaining the
> pfifo_fast qdisc, it is shown a TOS field mapping table and also it
> appears a command line version:
>
> "The last column shows the result of the default priomap. On the
> commandline, the default priomap looks like this:
> 1, 2, 2, 2, 1, 2, 0, 0 , 1, 1, 1, 1, 1, 1, 1, 1
>
> This means that priority 4, for example, gets mapped to band number 1. The
> priomap also allows you to list higher priorities (> 7) which do not
> correspond to TOS mappings, but which are set by other means."
>
> The numbers on the command line version are 16, thus I presume its a one
> to one corespondation to the table, only that it is completly different. I
> dont see any explanation why it is like that. Shouldnt that be:
> 1,2,1,1,2,2,2,2,0,0,0,0,1,1,1,1 ?
>
> Thanks
>
> ----------------------------
> Mihai RUSU
>

nope. Try the following:

# tc qdisc del dev eth0 root
# tc qdisc add dev eth0 root handle 1: prio
# tc -s qdisc ls dev eth0
qdisc prio 1: bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1
 Sent 455336 bytes 1237 pkts (dropped 0, overlimits 0)

which is the default priomap on the commandline. The one you mention is the
priomap in the kernel for pfifo_fast.

I usually set the priomap manually to get the latter priomap. example:
tc qdisc add dev eth0 root handle 1: prio bands 4 priomap 2 3 2 2 3 3 3 3 1
1 1 1 2 2 2 2
(which is the kernels default + 1, here I use the 0 band for very important
traffic which goes above the TOS-field.)

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