[dm-devel] cmwq and dm-crypt devices?
Milan Broz
mbroz at redhat.com
Wed Nov 3 13:02:14 UTC 2010
On 11/03/2010 01:33 PM, Andi Kleen wrote:
>> Async crypto is not solved at all by your patch.
>
> You mean async crypto with 10 stacked devices? Find me a single
> user who does that.
It is just quick reproducer. It can happen with several
non-stacked devices too and just points to the
problem that there was reason for dedicated threads per device.
I would really prefer If we can fix the scalable problem without
dismantling existing stacking support.
There are users who plans to massively use many dm-crypt devices
in system and this will ensure that it will work properly
even in bizarre configurations.
> Traditionally stacking didn't work very
> well in the kernel due to the limited kernel stack overflows.
> I don't think that's significantly different here.
Sorry? device-mapper is designed to be stackable. And it works.
> Anyways stacking could be probably fixed, but it's also that 99.999999%
> of all dm-crypt users don't stack or use async but simply need a
> scalable dm-crypt. Extreme stacking is extremly low on the
> priority list.
>
> Right now dm-crypt seems to have other problems anyways that need
> to be addressed first.
I fixed many bugs in dm-crypt which were caused by reducing problem
to "common situation" (and which appeared later).
Please can you fix you patch instead of this argumentation?
I know that some fix is needed, I am using the patch myself and I am also
receiving mails requesting it.
The whole thread was reopened because we tried to find solution
to this - IOW fix your patch.
Milan
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