Re: [Qemu-devel] [PATCH 4/4] block: Cater to iscsi with non-power-of-2 discard

[Eric Blake]

On 10/25/2016 07:42 AM, Peter Lieven wrote:
>>
>> But hey, that firmware is seriously weird. :)
> 
> Yes, so you would not change the new implementation?
> 
> Even if the discard is e.g. 1MB it could theretically be that internally
> the device has a finer granularity. Its an optimal discard alignment
> not the minimum required discard size. I think thats a difference.
> It does not say I can't handle smaller discards.

The firmware is probably technically buggy for advertising too large of
a minimum granularity, if it can piece together smaller requests into a
larger discard.  If discards need to happen at a smaller granularity,
the firmware (or kernel quirk system) should fix the advertisement to
the actual granularity that it will honor.  I don't see a reason to
change qemu's current behavior.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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