[dm-devel] cmwq and dm-crypt devices?
Alasdair G Kergon
agk at redhat.com
Wed Nov 3 13:18:35 UTC 2010
On Wed, Nov 03, 2010 at 01:33:47PM +0100, Andi Kleen wrote:
> 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.
Stacking in dm works reasonably well today and many people rely upon
that.
> Anyways stacking could be probably fixed, but it's also that 99.999999%
Please fix this regression the patch causes then or give some
fundamental arguments why we can't satisfy the two requirements
simultaneously: I just don't understand why it is necessary to cause a
regression in stacking/low memory support in order to provide the
performance boost in the way you desire. The two things ought to be
independent of each other.
(And I remain sceptical about the suitability of the patch even with a
stack of just two or three layers as I don't see anything in the failed
tests that shows why similar failures couldn't in principle affect
people with thinner stacks. The compromise I suggested was to amend the
patch to introduce the change only for non-stacked devices.)
Alasdair
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