Messages in this thread |  | | Date | Sun, 20 May 2001 15:40:44 +0200 | From | Andrea Arcangeli <> | Subject | Re: alpha iommu fixes |
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On Sun, May 20, 2001 at 04:12:34PM +0400, Ivan Kokshaysky wrote: > On Sun, May 20, 2001 at 04:40:13AM +0200, Andrea Arcangeli wrote: > > I was only talking about when you get the "pci_map_sg failed" because > > you have not 3 but 300 scsi disks connected to your system and you are > > writing to all them at the same time allocating zillons of pte, and one > > of your drivers (possibly not even a storage driver) is actually not > > checking the reval of the pci_map_* functions. You don't need a pte > > memleak to trigger it, even regardless of the fact I grown the dynamic > > window to 1G which makes it 8 times harder to trigger than in mainline. > > I think you're too pessimistic. Don't mix "disks" and "controllers" --
I'm not pessimistic, I'm fairly relaxed also with a 512Mbyte dynamic window (that's why I did the change in first place) and I agree that it should take care of hiding all those bugs on 99% of hardware configurations, but OTOH I don't want things to work by luck and I'd prefer if the real bugs gets fixed as well eventually.
> SCSI adapter with 10 drives attached is a single DMA agent, not 10 agents.
you can do simultaneous I/O to all the disks, so you will keep those dma entries for the SG for each disk in-use at the same time.
> If you're so concerned about Big Iron, go ahead and implement 64-bit PCI > support, it would be right long-term solution. I'm pretty sure that > high-end servers use mostly this kind of hardware.
Certainly 64bit pci is supported but that doesn't change the fact you can as well have 32bit devices on those boxes.
> Oh, well. This doesn't mean that I'm disagreed with what you said. :-) > Driver writers must realize that pci mappings are limited resources.
Exactly.
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