Re: [LARTC] HTB MPU

[Andy Furniss <andy.furniss@dsl.pipex.com>]

Jason Boxman wrote:
> On Monday 17 May 2004 18:36, Andy Furniss wrote:
> <snip>
> 
>>Could be this then -
>>
>>You can make HTB more accurate by setting HTB_HYSTERESIS to 0 in
>>net/sched/sch_htb.c.
>>
> 
> 
> I have been messing with producing graphs with SNMP, so I only just did this.  
> I was hoping to get before and after graphs to verify any changes, but I 
> finally just did it.

I was just thinking about making ping graphs with sed/xplot myself. Is 
it easy with SNMP?

> 
> Lucky for me, my ADSL line died tonight, so when it came back up I was able to 
> see my ping on a completely idle link.  Using HTB with HTB_HYSTERESIS  set to 
> 0 appears to have greatly reduced my ping time.  It still skips up more often 
> than when the link is completely idle, but it appears to be (without any 
> graphs to verify) a marked improvement.  (Now I see more 75ms and an 
> occasional 145ms instead of the complete reverse.)

Good - there is another timing tweak I should have mentioned which you 
may or may not be able to use.

http://www.docum.org/stef.coene/qos/faq/cache/40.html

I use this - but still notice some things (not TC related) use 100hz. 
When I finally finish my LFS setups I am going to try and tweak this aswell.

> 
> 68/70/75 out of 20 ICMP packets when idle.
> 68.3/91.6/215.7 ms out of 323 ICMP packets at 85% utilization.

Assuming there is only upstream traffic for the test that still seems 
high - but then I don't know what your pinging - my first hop is usually OK.

What is the best min you can get pinging your first hop with an empty 
line  - with and without traffic control in use. TC it's self doesn't 
seem to affect my best empty line rates.

At 85% you should see max around 70-80 assuming 25ms baseline pings.

> 
> From the comments in sch_htb.c I take it I just traded speed for accuracy in 
> some of HTB's calculations, which on such a slow link is probably not an 
> issue?
> 

Yes.

Andy.

_______________________________________________
LARTC mailing list / LARTC@mailman.ds9a.nl
http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/