On Tue, 16 Feb 2010, Mel Gorman wrote: > Because how do I tell in advance that the data I am migrating from DMA can > be safely relocated to the NORMAL zone? We don't save GFP flags. Granted, > for DMA, that will not matter as pages that must be in DMA will also not by > migratable. However, buffer pages should not get relocated to HIGHMEM for > example which is more likely to happen. It could be special cased but > I'm not aware of ZONE_DMA-related pressure problems that would make this > worthwhile and if so, it should be handled as a separate patch series. Oh there are numerous ZONE_DMA pressure issues if you have ancient / screwed up hardware that can only operate on DMA or DMA32 memory. Moving page cache pages out of the DMA zone would be good. A write request will cause the page to bounce back to the DMA zone if the device requires the page there. But I also think that the patchset should be as simple as possible so that it can be merged soon. > Ah, it was 2009 when I last kicked this around heavily :) I'll update > it. But it was authored in 2009. May be important if patent or other copyright claims arise. 2009-2010? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>