Re: I/O topology fixes for big physical block size

[Jens Axboe <jaxboe@fusionio.com>]

On 2010-09-28 07:14, Martin K. Petersen wrote:
>>>>>> "Jens" == Jens Axboe <jaxboe@fusionio.com> writes:
> 
> Jens> Yes, from a correctness point of view it doesn't matter, but when
> Jens> people go looking up fixes for whatever reason, it's much better
> Jens> to include such a fix in the original patch so it's not missed.
> 
> I have talked to a few standards people today. They are of the opinion
> that the device's usage of the physical block exponent is incorrect. And
> that the device must provide the Block Limits and the TP VPD if thin
> provisioning is enabled.
> 
> However, devices with 8KiB physical blocks are shipping and 16KiB ditto
> are right around the corner.  Which says to me that it's important to
> report the correct thing to userland so we can cause allocators to align
> on the right boundaries, etc. If we artificially clamp the physical
> block size parameter in the kernel we are losing information. Note that
> there are no kernel users of the physical block size parameter at all.

With the revised understanding that this is purely the IO hint, then yes
I agree we should not clamp it.

-- 
Jens Axboe