Re: cmwq and dm-crypt devices?

[Andi Kleen <andi@firstfloor.org>]

> 
> > 2) scale up the number of workqueue threads used for a single dm-crypt
> >    device so that a device can realize per-cpu concurrency (to address
> >    Andi's scalability concerns: https://patchwork.kernel.org/patch/244031/)

They are already addressed in my patchkit and the patches seem to be used
by more and more users. It's just you guys who are behind.

> > 
> >    [the desired locality is currently missing due to dm-crypt's current
> >     use of WQ_UNBOUND; so it is clear the way the workqueues are created
> >     will be important]
> 
> I don't know enough about dm-crypt workload to tell whether per-cpu
> affinity would be better or not, but it's really a simple matter of

CPU affinity and an own thread makes sense for the crypto helper
because it uses up a lot of CPU time.

For the IO helper you probably still want CPU affinity, but it 
can be concurrency managed.

-andi