>>>>> "Rafael" == Rafael David Tinoco <rafael.tin...@canonical.com> writes:
Rafael> It seems that changing discard method from UNMAP to WRITE Rafael> SAME(16) without using NDOB bit (as first described in Rafael> sbc3r35b.pdf) can cause performance problems on big discards Rafael> (since data-out buffer will be checked for every WRITE SAME Rafael> command). I think this is happening after this commit, since Rafael> NDOB bit wasn't implemented with this change (afaik, iirc). We don't currently use NDOB since there is no VPD parameter to key off of. I am also not aware of any devices that actually support it. I am working on some patches that changes how we submit write same and unmap down the stack to make it easier for the target subsystem to provide zeroing guarantees. Those changes will clean some of this up but they are 4.8 material. -- Martin K. Petersen Oracle Linux Engineering
