diff options
| author | Li RongQing <lirongqing@baidu.com> | 2024-07-11 20:11:30 +0800 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2024-08-13 12:09:35 -0400 |
| commit | c9b35a6f4edea698a5bb4dd8029e7104ee0a3726 (patch) | |
| tree | d02be924bf3e7c4ac041b03a4abbe181bbdba450 /virt | |
| parent | 238d3d63d1e27c8d9733b48f7b682fc6aba86672 (diff) | |
KVM: eventfd: Use synchronize_srcu_expedited() on shutdown
When hot-unplug a device which has many queues, and guest CPU will has
huge jitter, and unplugging is very slow.
It turns out synchronize_srcu() in irqfd_shutdown() caused the guest
jitter and unplugging latency, so replace synchronize_srcu() with
synchronize_srcu_expedited(), to accelerate the unplugging, and reduce
the guest OS jitter, this accelerates the VM reboot too.
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Message-ID: <20240711121130.38917-1-lirongqing@baidu.com>
[Call it just once in irqfd_resampler_shutdown. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt')
| -rw-r--r-- | virt/kvm/eventfd.c | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c index 229570059a1b..992f9beb3e7d 100644 --- a/virt/kvm/eventfd.c +++ b/virt/kvm/eventfd.c @@ -97,18 +97,19 @@ irqfd_resampler_shutdown(struct kvm_kernel_irqfd *irqfd) mutex_lock(&kvm->irqfds.resampler_lock); list_del_rcu(&irqfd->resampler_link); - synchronize_srcu(&kvm->irq_srcu); if (list_empty(&resampler->list)) { list_del_rcu(&resampler->link); kvm_unregister_irq_ack_notifier(kvm, &resampler->notifier); /* - * synchronize_srcu(&kvm->irq_srcu) already called + * synchronize_srcu_expedited(&kvm->irq_srcu) already called * in kvm_unregister_irq_ack_notifier(). */ kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID, resampler->notifier.gsi, 0, false); kfree(resampler); + } else { + synchronize_srcu_expedited(&kvm->irq_srcu); } mutex_unlock(&kvm->irqfds.resampler_lock); @@ -126,7 +127,7 @@ irqfd_shutdown(struct work_struct *work) u64 cnt; /* Make sure irqfd has been initialized in assign path. */ - synchronize_srcu(&kvm->irq_srcu); + synchronize_srcu_expedited(&kvm->irq_srcu); /* * Synchronize with the wait-queue and unhook ourselves to prevent @@ -384,7 +385,7 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args) } list_add_rcu(&irqfd->resampler_link, &irqfd->resampler->list); - synchronize_srcu(&kvm->irq_srcu); + synchronize_srcu_expedited(&kvm->irq_srcu); mutex_unlock(&kvm->irqfds.resampler_lock); } @@ -523,7 +524,7 @@ void kvm_unregister_irq_ack_notifier(struct kvm *kvm, mutex_lock(&kvm->irq_lock); hlist_del_init_rcu(&kian->link); mutex_unlock(&kvm->irq_lock); - synchronize_srcu(&kvm->irq_srcu); + synchronize_srcu_expedited(&kvm->irq_srcu); kvm_arch_post_irq_ack_notifier_list_update(kvm); } @@ -608,7 +609,7 @@ kvm_irqfd_release(struct kvm *kvm) /* * Take note of a change in irq routing. - * Caller must invoke synchronize_srcu(&kvm->irq_srcu) afterwards. + * Caller must invoke synchronize_srcu_expedited(&kvm->irq_srcu) afterwards. */ void kvm_irq_routing_update(struct kvm *kvm) { |