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Re: More measurements

To: Andrew Morton <andrewm@xxxxxxxxxx>
Subject: Re: More measurements
From: Jes Sorensen <jes@xxxxxxxxxxxxx>
Date: 30 Jan 2001 21:52:14 +0100
Cc: netdev@xxxxxxxxxxx
In-reply-to: Andrew Morton's message of "Tue, 30 Jan 2001 01:04:10 +1100"
References: <3A75785A.42B9E7CE@xxxxxxxxxx>
Sender: owner-netdev@xxxxxxxxxxx
User-agent: Gnus/5.070096 (Pterodactyl Gnus v0.96) Emacs/20.4
>>>>> "Andrew" == Andrew Morton <andrewm@xxxxxxxxxx> writes:

Andrew> - eepro100 generates more interrupts doing TCP Tx, but not TCP
Andrew> Rx.  I assume it doesn't do Tx mitigation?

Andrew> - Changing eepro100 to use IO operations instead of MMIO slows
Andrew> down this dual 500MHz machine by less than one percent at 100
Andrew> mbps.  At 12,000 interrupts per second. Why all the fuss about
Andrew> MMIO?

Ingo or Don Becker (sorry don't remember if it was Ingo or Don) did
some tests showing that the write speed to IO ports was about 10 times
the slower and read about 5 times slower. There is also the issues of
stalling the bus. This may not all show up in actual transmission
speeds etc.


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