• Sagi Grimberg's avatar
    IB/device: Convert ib-comp-wq to be CPU-bound · b7363e67
    Sagi Grimberg authored
    
    
    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: default avatarSagi Grimberg <sagi@grimberg.me>
    Reviewed-by: default avatarBart Van Assche <bart.vanassche@sandisk.com&gt;-->
    Signed-off-by: default avatarDoug Ledford <dledford@redhat.com>
    b7363e67