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    SubjectRe: [PATCH] block: respect virtual boundary mask in bvecs
    On Mon, Nov 05, 2018 at 12:50:50PM +0100, Johannes Thumshirn wrote:
    > On 05/11/2018 11:55, Ming Lei wrote:
    > > On Mon, Nov 05, 2018 at 11:23:01AM +0100, Johannes Thumshirn wrote:
    > >> With drivers like iSer we are seeing a lot of bio splitting and smaller I/Os
    > >> being submitted to the driver.
    > >>
    > >> The root cause of this issue that the virtual boundary mask code does not take
    > >> into consideration that some of the memory segments in the SG list may have
    > >> come from a huge memory page that is being managed in the SG list as 4K
    > >
    > > I guess you mean something like 64K PAGE_SIZE, instead of huge page.
    >
    > No I mean like a 2M page from an upper layer.

    If you mean the real huge page, this patch shouldn't have made a difference
    because bio_vec->bv_offset is in [0, PAGE_SIZE), and iSer sets virt
    boundary as 4K - 1.

    However, things will change after multipage bvec is introduced.

    Thanks,
    Ming

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