With the zerocopy patch, acenic always disables MWI by default.
>> And can a general rule be applied here? Newer Tulip hardware also
>> has the ability to enable/disable MWI usage, IIRC.
>
> And so do eepro100 and starfire. On the eepro100 we're enabling MWI
> unconditionally, and on the starfire we disable it unconditionally...
>
> I should probably take a look at acenic's use of PCI_COMMAND_INVALIDATE
> to see when it gets activated. Some benchmarking would probably help,
> too -- maybe later today.
I did some testing with starfire, and the results are inconclusive --
at least on my P-III is makes absolutely no difference. Does it make
a difference on other architectures? sparc64, ia64 maybe?
I should probably rephrase this: MWI makes no difference on i386, but
it is claimed that using MWI *reduces* performance on some systems.
Are there any systems on which MWI *increases* performance?
I've added some code to the starfire driver that allows changing the
use of MWI at module load time, just in case. By default, it activates
it.
Ion
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