Re: [PATCH RESEND] IB/device: Convert ib-comp-wq to be CPU-bound

[Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

On Wed, 2017-03-08 at 22:03 +0200, Sagi Grimberg wrote:
> This workqueue is used by our storage target mode ULPs
> via the new CQ API. Recent observations when working
> with very high-end flash storage devices reveal that
> UNBOUND workqueue threads can migrate between cpu cores
> and even numa nodes (although some numa locality is accounted
> for).
> 
> While this attribute can be useful in some workloads,
> it does not fit in very nicely with the normal
> run-to-completion model we usually use in our target-mode
> ULPs and the block-mq irq<->cpu affinity facilities.
> 
> The whole block-mq concept is that the completion will
> land on the same cpu where the submission was performed.
> The fact that our submitter thread is migrating cpus
> can break this locality.
> 
> We assume that as a target mode ULP, we will serve multiple
> initiators/clients and we can spread the load enough without
> having to use unbound kworkers.
> 
> Also, while we're at it, expose this workqueue via sysfs which
> is harmless and can be useful for debug.
> 
> Signed-off-by: Sagi Grimberg <sagi-NQWnxTmZq1alnMjI0IkVqw@public.gmane.org>

Thanks, applied.

-- 
Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
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