Re: [PATCH 3/3] nvme-multipath: add "use_nonoptimized" module option

Hannes Reinecke
2023-09-27T07:41:45Z

On 9/25/23 18:31, Ewan D. Milne wrote:
> Setting nvme_core.use_nonoptimized=true will cause the path
> selector to treat optimized and nonoptimized paths equally.
>
> This is because although an NVMe fabrics target device may report
> an unoptimized ANA state, it is possible that other factors such
> as fabric latency are a large factor in the I/O service time. And,
> throughput may improve overall if nonoptimized ports are also used.
>
> Signed-off-by: Ewan D. Milne <emilne@redhat.com>
> ---
> drivers/nvme/host/multipath.c | 22 +++++++++++++++++++---
> 1 file changed, 19 insertions(+), 3 deletions(-)
>
No. Please don't.

There's a reason why controllers specify paths as 'active/optimized' or
'active/non-optimized'. If they had wanted us to use all paths they
would have put them into the same group.
They tend to get very unhappy if you start using them at the same time.
(Triggering failover etc.)

Cheers,

Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare@suse.de +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Ivo Totev, Andrew
Myers, Andrew McDonald, Martje Boudien Moerman