Re: [PATCH] starfire reads irq before pci_enable_device.

From: Ion Badulescu (
Date: Tue Feb 13 2001 - 21:05:19 EST

On Tue, 13 Feb 2001 12:29:16 -0800, Ion Badulescu <> wrote:
> On Tue, 13 Feb 2001 07:06:44 -0600 (CST), Jeff Garzik <> wrote:
>> On 12 Feb 2001, Jes Sorensen wrote:
>>> In fact one has to look out for this and disable the feature in some
>>> cases. On the acenic not disabling Memory Write and Invalidate costs
>>> ~20% on performance on some systems.
>> And in another message, On Mon, 12 Feb 2001, David S. Miller wrote:
>>> 3) The acenic/gbit performance anomalies have been cured
>>> by reverting the PCI mem_inval tweaks.
>> Just to be clear, acenic should or should not use MWI?

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 is better to keep your mouth shut and be thought a fool,
            than to open it and remove all doubt.
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This archive was generated by hypermail 2b29 : Thu Feb 15 2001 - 21:00:23 EST