Re: [LARTC] HTB doesn't give me the promised rate: cpufreq?

From: DervishD <lartc@dervishd.net>
To: lartc@vger.kernel.org
Subject: Re: [LARTC] HTB doesn't give me the promised rate: cpufreq?
Date: Tue, 28 Aug 2007 07:45:24 +0000	[thread overview]
Message-ID: <20070828074524.GE17475@DervishD> (raw)
In-Reply-To: <20070826221407.GA1944@DervishD>

    Hi Andy :)

 * Andy Furniss <lists@andyfurniss.entadsl.com> dixit:
> DervishD wrote:
> >    I've thought that the culprit may be cpufreq. I have cpufreq scaling
> >activated, and cpufreq reduces the clock speed from 1800MHz to 1000MHz
> >when the processor is idle. This is more or less the same amount that I
> >"lose" in the rate. May this be the problem? How to fix without
> >deactivating cpufreq?
> 
> Could be - I don't know. Forgetting cpufreq htb can be limited by Hz if 
> the burst size is too small.

    I've tested with a burst size of 1500 (my MTU) and with precomputed
values (which are 1614b for burst, 1633b for cburst) and the result is
the same.

    I'm using HZ\x1000 in my kernel, so my resolution is 1ms. According
to HTB docs, the burst that will cause the rate to be burst-bound is
272000bit * 1m = 272bit. 

> >    I'm using htb+sqf, and I can post here my tc setup if needed (is
> >quite short), including the filters. It should be OK, since it has been
> >working for almost two years. Right now I cannot disable cpufreq because
> >temperature problems, and I cannot shut down the machine either, so I
> >cannot test if cpufreq is the culprit, that's why I'm asking. I haven't
> >found anything while googling, either.
> 
> If you have perturb too low on sfq the packet reordering it causes could 
> make the sender back off too much.

    I have a perturb of 10, as I've always used.

    Finally I could turn the machine off and clean the CPU fan, so I've
make a test using the performance governor and the ondemand governor of
cpufreq and yes, the problem is the cpufreq thing :((((

    I'll start a new thread here for this and will report to LKML too.

    Thanks for your answer :))

    Raúl Núñez de Arenas Coronado

-- 
Linux Registered User 88736 | http://www.dervishd.net
It's my PC and I'll cry if I want to... RAmen!
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