netdev - Re: HTB accuracy for high speed

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Date:	Thu, 21 May 2009 01:07:25 +0300
From:	Vladimir Ivashchenko <hazard@...ncoudi.com>
To:	Jarek Poplawski <jarkao2@...il.com>
Cc:	netdev@...r.kernel.org, kaber@...sh.net, davem@...emloft.net,
	devik@....cz, Antonio Almeida <vexwek@...il.com>
Subject: Re: HTB accuracy for high speed


> > > 
> > > I guess you should send some logs. Your previous report seem to show
> > 
> > Can you give some hints on which logs you would like to see?
> 
> Similarly to Antonio's: ifconfigs and tc -s for qdiscs and classes at
> the beginning and at the end of testing.

Ok, it seems that I finally found what is causing my HTB on 2.6.29 not
to reach full throughput: dst hashing on sfq with high divisor value.

2.6.21 esfq divisor 13 depth 4096 hash dst - 680 mbps
2.6.29 sfq WITHOUT "flow hash keys dst ... " (default sfq) - 680 mbps
2.6.29 sfq + "flow hash keys dst divisor 64" filter - 680 mbps
2.6.29 sfq + "flow hash keys dst divisor 256" filter - 660 mbps
2.6.29 sfq + "flow hash keys dst divisor 2048" filters - 460 mbps

I'm using high sfq hash divisor in order to decrease the number of
collisions, there are several thousands of hosts behind each of the
classes. 

Any ideas why increasing the sfq divisor size results in drop of
throughput ?

Attached are diagnostics gathered in case of divisor 2048.

-- 
Best Regards,
Vladimir Ivashchenko
Chief Technology Officer
PrimeTel PLC, Cyprus - www.prime-tel.com
Tel: +357 25 100100 Fax: +357 2210 2211


Download attachment "sfqtest.tar.gz" of type "application/x-compressed-tar" (66428 bytes)