• Bhaktipriya Shridhar's avatar
    KVM: Remove deprecated create_singlethread_workqueue · 3706feac
    Bhaktipriya Shridhar authored
    The workqueue "irqfd_cleanup_wq" queues a single work item
    &irqfd->shutdown and hence doesn't require ordering. It is a host-wide
    workqueue for issuing deferred shutdown requests aggregated from all
    vm* instances. It is not being used on a memory reclaim path.
    Hence, it has been converted to use system_wq.
    The work item has been flushed in kvm_irqfd_release().
    
    The workqueue "wqueue" queues a single work item &timer->expired
    and hence doesn't require ordering. Also, it is not being used on
    a memory reclaim path. Hence, it has been converted to use system_wq.
    
    System workqueues have been able to handle high level of concurrency
    for a long time now and hence it's not required to have a singlethreaded
    workqueue just to gain concurrency. Unlike a dedicated per-cpu workqueue
    created with create_singlethread_workqueue(), system_wq allows multiple
    work items to overlap executions even on the same CPU; however, a
    per-cpu workqueue doesn't have any CPU locality or global ordering
    guarantee unless the target CPU is explicitly specified and thus the
    increase of local concurrency shouldn't make any difference.
    Signed-off-by: default avatarBhaktipriya Shridhar <bhaktipriya96@gmail.com>
    Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
    3706feac
eventfd.c 22 KB