Messages in this thread | | | Date | Fri, 03 Mar 2006 14:42:44 -0500 | From | Jeff Garzik <> | Subject | Re: sg regression in 2.6.16-rc5 |
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Linus Torvalds wrote: > For example, I think the IDE driver defaults to a maximum transfer of 256 > sectors, and the same number of max scatter-gather entries. Some > controllers will actually lower that, due to silly hw problems.
Yep. Just to be specific:
256 max sectors IDE driver, 200 max sectors libata (due to driver not hardware).
256 max s/g entries hardware limit, but due to a IOMMU merging worst case libata (IDE driver too?) winds up with a 128 entry practical limit.
Newer SATA controllers eliminate the s/g entry limit and DMA boundary limits, but its still 256 max-sectors for ATAPI (64k for LBA48 ATA).
Jeff
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