Re: Increased memory usage with scsi-mq

From: Christoph Hellwig
Date: Sat Aug 05 2017 - 04:44:50 EST

On Fri, Aug 04, 2017 at 10:00:47PM +0100, Richard W.M. Jones wrote:
> I read your slides about scsi-mq and it seems like a significant
> benefit to large machines, but could the out of the box defaults be
> made more friendly for small memory machines?

The default inumber of queues and queue depth and thus memory usage is
set by the LLDD.

Try to reduce the can_queue value in virtio_scsi and/or make sure
you use the single queue variant in your VM (which should be tunable
in qemu).