Re: [PATCH RFC] nohz,blk-mq: do not create blk-mq workqueues on nohz dedicated CPUs

Rik van Riel
2015-04-01T16:12:44Z

On 03/31/2015 11:43 AM, Jens Axboe wrote:

> That'd be easy enough to do, that's how blk-mq handles offline CPUs as
> well. The attached patch is completely untested, but will handle offline
> or nohz CPUs in the same fashion - they will punt to hardware queue 0,
> which is mapped to CPU0 (and others, depending on the queue vs CPU ratio).

I have done some sanity testing with your patch,
starting a KVM guest with vcpus and emulator threads
all pinned to nohz_full cpus.

The guest is still able to do disk IO, so things
appear to work...

Thanks for looking into this, Jens.

Tested-by: Rik van Riel <riel@redhat.com>