[LARTC] tc htb stats

[LARTC] tc htb stats

[David DeLauro]

I have an htb qdisc setup and it is shaping my traffic wonderfully but
I've just recently started taking a look at the output from the command

tc -s class ls dev eth?

Looking at the "rate" line I thought to myself..."cool I can use this to
graph throughput avg.es without having to worry about the "Sent bytes"
rolling over or being lost when the htb qdisc is recreated"  _BUT_ it
seems the rates are inaccurate.  When I look at the rate my cisco router
reports for a 5min avg and I look at a calculated 5min average (30 polls
of the tc once every 10sec) for tc they are very different.  The cisco is
reported as ~2090kb/s and tc reports my parent as ~251kb/s.  Even if I
take all the classes separately and add the averages together I get closer
but not that much closer.  Is my math wrong?  How does the tc/htb qdisc
figure the avg. rate?

-- 
David DeLauro

Talk sense to a fool and he calls you foolish. - Euripides

Those who do not think about their own sins make up for it by thinking incessantly about the sins of others. - C. S. Lewis  (God in the Dock, "Miserable Offenders," p. 124)

Never undertake anything for which you wouldn't have the courage to ask the blessing of heaven. - G. C. Lichtenberg (1742-1799)

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Re: [LARTC] tc htb stats

[Martin A. Brown]

David,

 : When I look at the rate my cisco router
 : reports for a 5min avg and I look at a calculated 5min average (30 polls
 : of the tc once every 10sec) for tc they are very different.  The cisco is
 : reported as ~2090kb/s and tc reports my parent as ~251kb/s.

 : Even if I take all the classes separately and add the averages together
 : I get closer but not that much closer.  Is my math wrong?  How does the
 : tc/htb qdisc figure the avg. rate?

$ expr 251 \* 8
2008

Snipped from http://www.docum.org/stef.coene/qos/docs/ :

  "When you use the tc command, you have to remember that mb = 1024 kb    1024 * 1024 b = byte/s and that mbit = 1024 kbit = 1024 * 1024 bit    bit/s."

Snipped from http://lartc.org/howto/lartc.qdisc.html :

  "Just to prevent confusion, tc uses the following rules for bandwith
   specification:

   mbps = 1024 kbps = 1024 * 1024 bps => byte/s
   mbit = 1024 kbit => kilo bit/s.
   mb = 1024 kb = 1024 * 1024 b => byte
   mbit = 1024 kbit => kilo bit.!

Are you certain your units are the same?  Strangely, the tc command line
tool uses kb for kilobytes/second.  I think 251 kilobytes-per-second is
quite close to 2090 kilobits-per-second.

Bye for now,

-Martin

-- 
Martin A. Brown --- SecurePipe, Inc. --- mabrown@securepipe.com

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Re: [LARTC] tc htb stats

[David DeLauro]

On Tue, 4 Feb 2003 At 10:20 -0600, mabrown-lartc@securepipe.com Articulated:

>
> Snipped from http://lartc.org/howto/lartc.qdisc.html :
>
>   "Just to prevent confusion, tc uses the following rules for bandwith
>    specification:
>
>    mbps = 1024 kbps = 1024 * 1024 bps => byte/s

Thanks Martin...

I was running under the assuption that "bps" was bits/s and "Bps" was
bytes/sec...

peace
-- 
David DeLauro

Hata ukinichukia la kweli nitakwambia - Kanga Proverb

Apart from God every activity is merely a passing whiff of insignificance. -  Alfred North Whitehead (1861-1947)

Never undertake anything for which you wouldn't have the courage to ask the blessing of heaven. - G. C. Lichtenberg (1742-1799)

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Re: [LARTC] tc htb stats

[Stef Coene]

On Tuesday 04 February 2003 17:30, David DeLauro wrote:
> On Tue, 4 Feb 2003 At 10:20 -0600, mabrown-lartc@securepipe.com Articulated:
> > Snipped from http://lartc.org/howto/lartc.qdisc.html :
> >
> >   "Just to prevent confusion, tc uses the following rules for bandwith
> >    specification:
> >
> >    mbps = 1024 kbps = 1024 * 1024 bps => byte/s
>
> Thanks Martin...
>
> I was running under the assuption that "bps" was bits/s and "Bps" was
> bytes/sec...
It's bit when there is bit, otherwise it's byte :)

Stef

-- 

stef.coene@docum.org
 "Using Linux as bandwidth manager"
     http://www.docum.org/
     #lartc @ irc.oftc.net


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