Messages in this thread | | | Date | Mon, 27 Oct 2008 19:21:41 +1100 | From | Jeremy Fitzhardinge <> | Subject | Re: [PATCH 2/2] x86: replace BIO_VMERGE_BOUNDARY with BIOVEC_PHYS_MERGEABLE |
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FUJITA Tomonori wrote: > The block layer always done the physical merge if possible. We don't > provide any kernel parameter to disable it. > > The iommu_bio_merge parameter had been used to enable the virtual > merge. As I wrote, the virtual merge feature was completely > removed. Effectively, the iommu_bio_merge parameter is meaningless > now. >
Under Xen, pages which appear to be pseudo-physically adjacent are not necessarily really physically adjacent. We need to hook BIOVEC_PHYS_MERGEABLE to prevent the bio layer from inappropriately merging requests across non-contiguous page boundaries.
J
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