From owner-freebsd-net@FreeBSD.ORG  Tue Jun 12 16:00:49 2007
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Date: Tue, 12 Jun 2007 11:34:41 -0400
From: "Stephan Koenig" <winterny@gmail.com>
To: freebsd-net@freebsd.org
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Subject: Tuning if_bge for high packet rates (receive descriptors/transmit
	descriptors?)
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X-List-Received-Date: Tue, 12 Jun 2007 16:00:49 -0000

Hello,

We have some servers that have a very high packet rate in a normal
production mode, and require polling to keep the CPU load reasonable.

We have Kern.HZ=4000, and even still, have some dropped packets.

On our servers that use the intel "em" driver, we have tuned the
drivers as following, by default, if_em.h has:

#define EM_MIN_TXD              80
#define EM_MAX_TXD_82543        256
#define EM_MAX_TXD              4096
#define EM_DEFAULT_TXD          EM_MAX_TXD_82543

#define EM_MIN_RXD              80
#define EM_MAX_RXD_82543        256
#define EM_MAX_RXD              4096
#define EM_DEFAULT_RXD          EM_MAX_RXD_82543


We have changed EM_DEFAULT_TXD and EM_DEFAULT_RXD to 4096 -- This
solved the problem on these servers.

The question is now what to do on our servers with Broadcom "bge"
series cards.  Does anyone know how to tune this driver in a similar
matter?

Thanks,
--Stephan