ACK: [SRU][Xenial][Yakkety][PATCH 1/1] block: relax check on sg gap

Seth Forshee seth.forshee at
Thu Apr 13 15:47:36 UTC 2017

On Thu, Apr 13, 2017 at 06:45:15AM -0400, Joseph Salisbury wrote:
> From: Ming Lei <ming.lei at>
> BugLink:
> If the last bvec of the 1st bio and the 1st bvec of the next
> bio are physically contigious, and the latter can be merged
> to last segment of the 1st bio, we should think they don't
> violate sg gap(or virt boundary) limit.
> Both Vitaly and Dexuan reported lots of unmergeable small bios
> are observed when running mkfs on Hyper-V virtual storage, and
> performance becomes quite low. This patch fixes that performance
> issue.
> The same issue should exist on NVMe, since it sets virt boundary too.
> Reported-by: Vitaly Kuznetsov <vkuznets at>
> Reported-by: Dexuan Cui <decui at>
> Tested-by: Dexuan Cui <decui at>
> Cc: Keith Busch <keith.busch at>
> Signed-off-by: Ming Lei <ming.lei at>
> Signed-off-by: Jens Axboe <axboe at>
> (cherry picked from commit 729204ef49ec00b788ce23deb9eb922a5769f55d)
> Signed-off-by: Joseph Salisbury <joseph.salisbury at>

Clean cherry pick, positive test results.

Acked-by: Seth Forshee <seth.forshee at>

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