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Does ISA interrupt latency harm overall system performance?

To: netdev@xxxxxxxxxxx
Subject: Does ISA interrupt latency harm overall system performance?
From: Steve Snyder <swsnyder@xxxxxxxx>
Date: Fri, 15 Jun 2001 23:09:54 -0700
Reply-to: swsnyder@xxxxxxxx
Sender: owner-netdev@xxxxxxxxxxx
I understand that ISA devices have a greater interrupt latency than PCI 
devices.  Does this greater latency deteriorate overall system performance 
or just the device whose interrupts are being serviced?

I've got 2 10Mbps Ethernet cards, one is an ISA card and the other PCI.  I 
use the ISA card as a secondary net device (eth1) which is connected to a 
cable modem.  Given that the cable modem will never saturate a 10Mbps 
Ethernet card, the ISA/PCI question shouldn't be relevant to networking 
performance.  I chose to use the ISA card because it leaves another PCI 
slot in my box (i686-based Linux 2.4.x) available for other uses.

Let me add one more thing to this context.  The PCI card is a 3Com 3C590 
"Vortex" so, according to the Linux doc, this device has busmastering 
capabilities.  Is this a factor in overall system performance?

Any thoughts on this?  Please cc me with any responses as I am not a 
subscriber to this list.

Thank you.

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