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Re: Problems with Intel e100 driver on new MIPS port, was: Advice needed

To: Michael Stickel <michael@cubic.org>
Subject: Re: Problems with Intel e100 driver on new MIPS port, was: Advice needed WRT very slow nfs in new port...
From: David Daney <ddaney@avtrex.com>
Date: Thu, 30 Jun 2005 11:23:29 -0700
Cc: linux-mips@linux-mips.org
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References: <42C34C4D.9020902@avtrex.com> <20050629.195743.48512936.imp@bsdimp.com> <42C359F8.4060000@avtrex.com> <20050629.204246.102671266.imp@bsdimp.com> <42C39066.2060406@cubic.org>
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Michael Stickel wrote:
M. Warner Losh wrote:

In message: <42C359F8.4060000@avtrex.com>
           David Daney <ddaney@avtrex.com> writes:
: M. Warner Losh wrote:
: > In message: <42C34C4D.9020902@avtrex.com>
: >             David Daney <ddaney@avtrex.com> writes:
: > : Does anyone have any idea what would cause 1000mS delay?
: > : > That's remarkably close to 1s. This often indicates that the transmit
: > of your next packet is causing the receive buffer to empty.  This is
: > usually due to blocked interrupts, or a failure to enable interrupts.
: > : : But I observe ever increasing counts for the device in /proc/interrupts. : So the interrupts are working somewhat.

Are you sure that you've routed the interrupts correctly?  Maybe those
interrupts are 'really' for a different device....
Add some debugging to the interrupt routine of the e100 and see what happens.

The interrupt routine is getting called each time a packet is received.

It looks like packets are not being transmitted until the interrupt for the the received packet is received.

If I ping the board at different intervals the round trip time is always almost exactly equal to the ping interval. So if I ping every 50mS the round trip time is 50mS, ping every 200mS gives a RTT of 200mS, etc.

Any more ideas?

I am thinking that perhaps the CPU write-back-queue is interfearing with writes to the NIC's registers. Perhaps I will try to disable it.

David Daney.

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