Messages in this thread | | | Date | Tue, 13 Feb 2001 18:05:19 -0800 | From | Ion Badulescu <> | Subject | Re: [PATCH] starfire reads irq before pci_enable_device. |
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On Tue, 13 Feb 2001 12:29:16 -0800, Ion Badulescu <ionut@moisil.cs.columbia.edu> wrote: > On Tue, 13 Feb 2001 07:06:44 -0600 (CST), Jeff Garzik <jgarzik@mandrakesoft.mandrakesoft.com> 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.
Ion
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