Messages in this thread | | | Subject | Re: [PATCH] starfire reads irq before pci_enable_device. | From | Jes Sorensen <> | Date | 12 Feb 2001 20:01:48 +0100 |
| |
>>>>> "Gérard" == Gérard Roudier <groudier@club-internet.fr> writes:
Gérard> On Fri, 9 Feb 2001, Alan Cox wrote:
>> DMA to main memory normally invalidates those lines in the CPU >> cache rather than the cache snooping and updating its view of them.
Gérard> In PCI, it is the Memory Write and Invalidate PCI transaction Gérard> that is intended to allow core-logics to optimize DMA this Gérard> way. For normal Memory Write PCI transactions or when the Gérard> core-logic is aliasing MWI to MW, the snooping may well Gérard> happen. All that stuff, very probably, varies a lot depending Gérard> on the core-logic.
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.
Jes - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://vger.kernel.org/lkml/
| |