Re: need to pick a solution for dm-crypt IV generation and do it! [was: Re: dm: submit stacked requests in irq enabled context]

[Neeraj Soni <neersoni@codeaurora.org>]

Thanks for inputs folks. So shall i conclude that there is no remedy 
available that can be applied on 4.4 and reverting this patch is only 
way forward to solve the degradation?

Neeraj


On 5/10/2017 8:25 PM, Gilad Ben-Yossef wrote:
> On Wed, May 10, 2017 at 5:45 PM, Mike Snitzer <snitzer@redhat.com> wrote:
>> On Wed, May 10 2017 at  9:37am -0400,
>> Gilad Ben-Yossef <gilad@benyossef.com> wrote:
>>
>>> On Wed, May 10, 2017 at 11:49 AM, Neeraj Soni <neersoni@codeaurora.org> wrote:
>>>> Hi Keith,
>>>>
>>>> Request based dm (dm-req-crypt) is being used for Disk Encryption solution
>>>> in Android used by Google. Also as i mentioned reverting this fix  improves
>>>> the RR/RW numbers so this proves the request based dm is coming into path
>>>> and is being used.
>>> Sadly, that is an out of tree module.
>>>
>>> Does it still use Qcom specific APIs in its implementation (qcrypto_* funcs)?
>>> It did the last time I've checked - and the driver that implements
>>> those is not upstream either...
>>>
>>> It makes it difficult to help - which is a shame since I am interested
>>> in enabling higher performance
>>> of dm-crypt when using HW based crypto transformation myself.
>> I have absolutely no interest in request-based dm-crypt.  It is a hack
>> to work-around limitations in crypto IV generation.
> I agree. This is why I've said I'm interested in a high performance dm-crypt,
> not "request based dm-crypt". They are trying to solve the same problem but
> with the wrong solution and doing so out of upstream.
>
> As the parlance of our time seems to go... sad. :-)
>
>
> Cheers,
> Gilad
>
>