Commit-ID: afdf92030c7c43b0f9b32b7edbe07ac3b13780f1 Gitweb: http://git.kernel.org/tip/afdf92030c7c43b0f9b32b7edbe07ac3b13780f1 Author: Jonathan Austin <jonathan.austin@xxxxxxx> AuthorDate: Wed, 11 Sep 2013 18:32:49 +0100 Committer: Pekka Enberg <penberg@xxxxxxxxxx> CommitDate: Thu, 12 Sep 2013 09:32:03 +0300 kvm tools: stop virtio console doing unnecessary input handling The asynchronous nature of the virtio input handling (using a job queue) can result in unnecessary jobs being created if there is some delay in handing input (the original function to handle the input returns immediately without the file having been read, and hence poll returns immediately informing us of data to read). This patch adds synchronisation to the threads so that we don't start polling input files again until we've read from the console. Signed-off-by: Jonathan Austin <jonathan.austin@xxxxxxx> Acked-by: Marc Zyngier <marc.zyngier@xxxxxxx> Signed-off-by: Pekka Enberg <penberg@xxxxxxxxxx> --- tools/kvm/virtio/console.c | 23 ++++++++++++++++++++--- 1 file changed, 20 insertions(+), 3 deletions(-) diff --git a/tools/kvm/virtio/console.c b/tools/kvm/virtio/console.c index 83c58bf..f982dab7 100644 --- a/tools/kvm/virtio/console.c +++ b/tools/kvm/virtio/console.c @@ -36,12 +36,17 @@ struct con_dev { struct virtio_console_config config; u32 features; + pthread_cond_t poll_cond; + int vq_ready; + struct thread_pool__job jobs[VIRTIO_CONSOLE_NUM_QUEUES]; }; static struct con_dev cdev = { .mutex = MUTEX_INITIALIZER, + .vq_ready = 0, + .config = { .cols = 80, .rows = 24, @@ -69,6 +74,9 @@ static void virtio_console__inject_interrupt_callback(struct kvm *kvm, void *par vq = param; + if (!cdev.vq_ready) + pthread_cond_wait(&cdev.poll_cond, &cdev.mutex.mutex); + if (term_readable(0) && virt_queue__available(vq)) { head = virt_queue__get_iov(vq, iov, &out, &in, kvm); len = term_getc_iov(kvm, iov, in, 0); @@ -81,7 +89,8 @@ static void virtio_console__inject_interrupt_callback(struct kvm *kvm, void *par void virtio_console__inject_interrupt(struct kvm *kvm) { - thread_pool__do_job(&cdev.jobs[VIRTIO_CONSOLE_RX_QUEUE]); + virtio_console__inject_interrupt_callback(kvm, + &cdev.vqs[VIRTIO_CONSOLE_RX_QUEUE]); } static void virtio_console_handle_callback(struct kvm *kvm, void *param) @@ -141,10 +150,16 @@ static int init_vq(struct kvm *kvm, void *dev, u32 vq, u32 page_size, u32 align, vring_init(&queue->vring, VIRTIO_CONSOLE_QUEUE_SIZE, p, align); - if (vq == VIRTIO_CONSOLE_TX_QUEUE) + if (vq == VIRTIO_CONSOLE_TX_QUEUE) { thread_pool__init_job(&cdev.jobs[vq], kvm, virtio_console_handle_callback, queue); - else if (vq == VIRTIO_CONSOLE_RX_QUEUE) + } else if (vq == VIRTIO_CONSOLE_RX_QUEUE) { thread_pool__init_job(&cdev.jobs[vq], kvm, virtio_console__inject_interrupt_callback, queue); + /* Tell the waiting poll thread that we're ready to go */ + mutex_lock(&cdev.mutex); + cdev.vq_ready = 1; + pthread_cond_signal(&cdev.poll_cond); + mutex_unlock(&cdev.mutex); + } return 0; } @@ -192,6 +207,8 @@ int virtio_console__init(struct kvm *kvm) if (kvm->cfg.active_console != CONSOLE_VIRTIO) return 0; + pthread_cond_init(&cdev.poll_cond, NULL); + virtio_init(kvm, &cdev, &cdev.vdev, &con_dev_virtio_ops, VIRTIO_DEFAULT_TRANS, PCI_DEVICE_ID_VIRTIO_CONSOLE, VIRTIO_ID_CONSOLE, PCI_CLASS_CONSOLE); -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html