Re: [dm-devel] [PATCH] DM-CRYPT: Scale to multiple CPUs v3

[Alasdair G Kergon <agk redhat com>]

On Wed, Oct 20, 2010 at 04:20:44PM +0200, Milan Broz wrote:
> this patch introduces apparent regressions in async crypto mode.
 
OK, thanks for performing those tests.

This patch is stalled until these problems are understood properly and
solutions are proposed.  I was prepared to overlook the regression in
stacked 'async' provided there was an inline FIXME explaining clearly
how to fix it in future should we need to, but I can't support a patch that
apparently breaks stacked sync encryption.

One solution might be to make the proposed changes only for non-stacked
configurations and leave stacks to work as they do today - either
detecting that automatically or having userspace supply a target
parameter to say whether or not to turn it on.  (For that, would need
tests to show a stack of many layers where only one is a crypt target
continues to work after the change.)

Alasdair