Re: [dm-devel] Fwd: [dm-crypt] [BUG] bad performance and system stalls when using dm-crypt

[Milan Broz <mbroz redhat com>]

On 10/24/2010 06:52 PM, dave b wrote:
>> So there are now several known situations when dm-crypt doesn't
>> perform as expected (another problem just appeared when using CFQ,
>> (because dm(-crypt) lost the issuing process reference)
>> see http://lkml.org/lkml/2010/10/24/59).
> 
> Thank for you replying  ^ ^
> I was aware with the problems and I am following Andi's dm-crypt
> per-cpu patch (I haven't applied or tested it). However, I didn't know
> about http://lkml.org/lkml/2010/10/24/59 -->
> So this may well be the root of the problem!
> Also, won't http://lkml.org/lkml/2010/10/24/59  need to be altered
> (again) to work with Andi's patch ?

CFQ related problem should be solved - probably device-mapper core
have to provide some help. (It is not only about dm-crypt,
lot of situations when IO is submitted from different internal process.
The proposed patch is not the proper and complete way how to solve it.)

For the per-cpu patch - I am waiting for replay, apparently some
additional work there is needed.
But I would like to solve it ASAP.

Milan