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Old 10-21-08, 08:03 PM   #18
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Join Date: Jul 2005
Location: Munich
Posts: 910
Default Re: What better, PCI-X MSI or Wired IRQ? [177.80]

Originally Posted by etherfish View Post
1263:         10       4434      11219  146033543   PCI-MSI-edge      eth0
1264:         35       4328     112565    3247738   PCI-MSI-edge      eth0
1265:         40       7271     164638    4115946   PCI-MSI-edge      eth0
I assume that the different interrupts correspond to different types of events and have different priorities.
A typical split i have frequently observed would be: transmission (TX-IRQ),
reception (RX-IRQ) and error case / state change (ERR-IRQ) - but i don't
think this is the case for your hardware, above.

The advantage of split MSIs over a single IRQ per device is that the driver
ISR doesn't need to check which type of event happened and then needs to
call the appropriate "sub-ISR" - the driver simply installs several ISRs
associated with the events, thus saving a few CPU cycles.


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