netdev - Re: htb parallelism on multi-core platforms

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Date:	Wed, 22 Apr 2009 17:02:06 +0300
From:	Radu Rendec <radu.rendec@...s.ro>
To:	Jarek Poplawski <jarkao2@...il.com>
Cc:	Denys Fedoryschenko <denys@...p.net.lb>, netdev@...r.kernel.org
Subject: Re: htb parallelism on multi-core platforms

On Sat, 2009-04-18 at 09:56 +0200, Jarek Poplawski wrote:
> Right, if you're using high resolution; there is a bug in tc, found by
> Denys, which causes wrong (too low) defaults for burst/cburst.
> 
> > Also worth to try HFSC.
> 
> Yes, it seems to be especially interesting for 64 bit boxes.

Hi Jarek,

Thanks for the hints! As far as I understand, HFSC is also implemented
as a queue discipline (like HTB), so I guess it suffers from the same
design limitations (doesn't span across multiple CPUs). Is this
assumption correct?

As for htb_hysteresis I actually haven't tried it. Although it is
definitely worth a try (especially if the average traffic grows), I
don't think it can compensate multithreading / parallel execution. At
least half of a packet processing time is consumed by classification
(although I am using hashes). I guess htb_hysteresis only affects the
actual shaping (which takes place after the packet is classified).

Thanks,

Radu Rendec

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