Re: [PATCH v3 03/13] mpt3sas: SGL to PRP Translation for I/Os to NVMe devices

Martin K. Petersen
2017-08-08T16:13:20Z

Suganath,

> + /*
> + ** Below code detects gaps/holes in IO data buffers.
> + ** What does holes/gaps mean?
> + ** Any SGE except first one in a SGL starts at non NVME page size
> + ** aligned address OR Any SGE except last one in a SGL ends at
> + ** non NVME page size boundary.
> + **
> + ** Driver has already informed block layer by setting boundary rules
> + ** for bio merging done at NVME page size boundary calling kernel API
> + ** blk_queue_virt_boundary inside slave_config.
> + ** Still there is possibility of IO coming with holes to driver because
> + ** of IO merging done by IO scheduler.

All this SGL to PRP code needs to go.

If you are seeing anything that's not a valid PRP after setting the
queue virt boundary then there's a block layer bug that needs to be
debugged and fixed. Regardless of whether you are using an I/O scheduler
or not.

--
Martin K. Petersen Oracle Linux Engineering