netdev - Re: htb parallelism on multi-core platforms

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Message-Id: <1241022071.6554.375.camel@blade.ines.ro>
Date:	Wed, 29 Apr 2009 19:21:11 +0300
From:	Radu Rendec <radu.rendec@...s.ro>
To:	Jarek Poplawski <jarkao2@...il.com>
Cc:	Jesper Dangaard Brouer <hawk@...u.dk>,
	Denys Fedoryschenko <denys@...p.net.lb>,
	netdev <netdev@...r.kernel.org>,
	Calin Velea <calin.velea@...enii.ro>
Subject: Re: htb parallelism on multi-core platforms

I finally managed to disable NAPI on e1000e - apparently it can only be
done on the "official" Intel driver (downloaded from their website), by
compiling with "make CFLAGS_EXTRA=-DE1000E_NO_NAPI". This doesn't seem
to be available in the (2.6.29) kernel driver.

With NAPI disabled, 4 (of 8) cores go to 100% (instead of only one), but
overall throughput *decreases* from ~110K pps (with NAPI) to ~80K pps.
This makes sense, since h/w interrupt is much more time consuming than
polling (that's the whole idea behind NAPI anyway).

Radu Rendec

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