Messages in this thread | | | Date | Fri, 25 Jun 2004 01:48:47 +1000 | From | Nick Piggin <> | Subject | Re: [discuss] Re: 32-bit dma allocations on 64-bit platforms |
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Andrea Arcangeli wrote:
> > why does it fail? note that with the lower_zone_reserve_ratio algorithm I > added to 2.4 all dma zone will be reserved for __GFP_DMA allocations so > you should have troubles only with 2.6, 2.4 should work fine. > > So with latest 2.4 it has to fail only if you already allocated 16M with > pci_alloc_consistent which sounds unlikely. > > the fact 2.6 lacks the lower_zone_reserve_ratio algorithm is a different > issue, but I'm confortable there's no other possible algorithm to solve > this memory balancing problem completely so there's no way around a > forward port. > > well 2.6 has a tiny hack like some older 2.4 that attempts to do what > lower_zone_reserve_ratio does, but it's not nearly enough, there's no > per-zone-point-of-view watermark in 2.6 etc.. 2.6 actually has a more > hardcoded hack for highmem, but the lower_zone_reserve_ratio has > absolutely nothing to do with highmem vs lowmem. it's by pure > coincidence that it avoids highmem machine to lockup without swap, but > the very same problem happens on x86-64 with lowmem vs dma.
2.6 has the "incremental min" thing. What is wrong with that? Though I think it is turned off by default. - 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://www.tux.org/lkml/
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