Date: Wed, 6 Dec 2006 11:54:01 +0300 From: Gleb Smirnoff <glebius@freebsd.org> To: oleg@freebsd.org, net@freebsd.org Cc: MQ <antinvidia@gmail.com> Subject: [antinvidia@gmail.com: some questions about bge(4)] Message-ID: <20061206085401.GH32700@cell.sick.ru>
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Forwarding to net@ list and to Oleg, who has made polling
support for bge(4).
----- Forwarded message from MQ <antinvidia@gmail.com> -----
From: MQ <antinvidia@gmail.com>
To: glebius@freebsd.org, davidch@broadcom.com
Subject: some questions about bge(4)
Date: Sat, 2 Dec 2006 09:32:27 +0000
Delivered-To: glebius@freebsd.org
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Hi David and Gleb,
I'm using several chips whose driver is bge(4). And now I have some
questions about the driver, would you please an answer for me?
My confusion is related with some codes in /sys/dev/mii/brgphy.c. The
bge(4) uses the callout to drive the watchdog. And the brgphy_service() is
called once per second. It calls brgphy_mii_phy_auto() every 5 seconds to
autonegotiate the media. Normally, it costs about 0.5ms in the first
function brgphy_service(), and about 5ms when autonegotiation is proceeded.
I haven't done streestest on it, consequently I don't know if this delay
will cause packets to be dropped. But I've enabled device polling with the
bge(4) on FreeBSD 6.1-RELEASE. If HZ is set to a high value(e.g. 4000), this
delay will cause the kern.polling.lost_polls to increase by one or two every
second. And for about five seconds, the lost poll will increase by at least
16 regularly. So I think this behavior has some impact on the systems that
enables device polling. Could we get something to make the bge(4) a bit more
friendly to the device polling? I don't know if autonegotiation is really
needed to be called so frequently when we are connected to a good network
environment. Can I modify the interval between two autonegotiations to have
less lost_polls? However, I have no idea about the long time spent in the
brgphy_service(), please take a look at the problem when you have enough
time.
Regards
MQ
----- End forwarded message -----
--
Totus tuus, Glebius.
GLEBIUS-RIPN GLEB-RIPE
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