Messages in this thread | | | From | David Mosberger <> | Date | Tue, 4 Dec 2001 09:43:02 -0800 | Subject | Re: [Linux-ia64] patch to no longer use ia64's software mmu |
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>>>>> On Tue, 4 Dec 2001 17:18:17 +0000 (GMT), Alan Cox <alan@lxorguk.ukuu.org.uk> said:
>> I think the issue at hand is whether, longer term, it is >> desirable to move all bounce buffer handling into the PCI DMA >> layer or whether Linux should continue to make bounce buffer >> management visible to drivers. I'd be interested in hearing >> opinions.
Alan> I think the performance figures we see currently answer that Alan> already.
The numbers I have seen so far don't make this obvious. Tony Luck reports 95Mbps with a CPU load of 20% after a fixing a performance bug in the software I/O TLB. Arjan reported the same 95Mbps figure with the highmem approach. Arjan didn't report the CPU load and neither Tony nor Arjan specified the test environment they were using.
Alan> IA64 also needs to correct its GFP_DMA to mean "low 16Mb" for Alan> ISA DMA. While there is no ISA DMA on ia64 (thankfully) many Alan> PCI cards have 26-31 bit limits.
We could do this if we there was a GFP_4GB zone. Now that 2.5 is open for business, it won't be long, right?
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