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Re: Au1550 ethernet throughput low

To: Dan Malek <dan@embeddedalley.com>
Subject: Re: Au1550 ethernet throughput low
From: jaypee@hotpop.com
Date: Mon, 18 Jul 2005 13:41:13 +0000
Cc: linux-mips <linux-mips@linux-mips.org>
In-reply-to: <b30d00c05783e8ed4fc6dcb29563e232@embeddedalley.com> (from dan@embeddedalley.com on Mon Jul 18 13:56:04 2005)
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Changing from CONFIG_DMA_NONCOHERENT to CONFIG_DMA_COHERENT make no difference,

It won't, because the Ethernet driver knows the hardware works
correctly for this peripheral and assumes coherent IO.

Any Ethernet performance differences among Au1xxx designs are
likely to be related to processor speed, the memory interface
configuration, or PHY issues (improperly configured or high
error rates).

I would agree but I see 100% throughput using YAMON on the same board. So it isn't the PHY or mem interface or processor speed as these are all configured from YAMON.

Even if I just send out rubbish packets (no memcpy) in au1000_xmit()
I don't get any better performance.

Basically for 40% of the time the MAC DMA is not busy and TX_ENABLE pin is zero.

So for whatever reason the kernel can only send 60Mbps. It is not limited by the MAC, it is limited by the speed that data is getting
through the IP stack.

My test just opens a socket and continually calls sendto().

There are no errors on either the MAC or PHY.

find attached my .config. If anyone has got this working
please post your config or send it me directly

Thanks
JP

- -- mailto:jaypee@hotpop.com
http://www.jaypee.org.uk
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Attachment: .config
Description: Text document

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