From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38532) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1c9DzT-00020y-95 for qemu-devel@nongnu.org; Tue, 22 Nov 2016 11:32:19 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1c9DzP-0004GI-AB for qemu-devel@nongnu.org; Tue, 22 Nov 2016 11:32:15 -0500 Received: from mx1.redhat.com ([209.132.183.28]:35008) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1c9DzP-0004G5-48 for qemu-devel@nongnu.org; Tue, 22 Nov 2016 11:32:11 -0500 From: Stefan Hajnoczi Date: Tue, 22 Nov 2016 16:31:46 +0000 Message-Id: <1479832306-26440-11-git-send-email-stefanha@redhat.com> In-Reply-To: <1479832306-26440-1-git-send-email-stefanha@redhat.com> References: <1479832306-26440-1-git-send-email-stefanha@redhat.com> Subject: [Qemu-devel] [PATCH v3 10/10] virtio: disable virtqueue notifications during polling List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: borntraeger@de.ibm.com, Paolo Bonzini , Karl Rister , Fam Zheng , Stefan Hajnoczi This is a performance optimization to eliminate vmexits during polling. It also avoids spurious ioeventfd processing after polling ends. Signed-off-by: Stefan Hajnoczi --- hw/virtio/virtio.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 66dd968..8f420cf 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -2057,6 +2057,13 @@ static void virtio_queue_host_notifier_aio_read(EventNotifier *n) } } +static void virtio_queue_host_notifier_aio_poll_begin(EventNotifier *n) +{ + VirtQueue *vq = container_of(n, VirtQueue, host_notifier); + + virtio_queue_set_notification(vq, 0); +} + static bool virtio_queue_host_notifier_aio_poll(void *opaque) { EventNotifier *n = opaque; @@ -2070,6 +2077,16 @@ static bool virtio_queue_host_notifier_aio_poll(void *opaque) return true; } +static void virtio_queue_host_notifier_aio_poll_end(EventNotifier *n) +{ + VirtQueue *vq = container_of(n, VirtQueue, host_notifier); + + virtio_queue_set_notification(vq, 1); + + /* Handle any buffers that snuck in after we finished polling */ + virtio_queue_host_notifier_aio_poll(n); +} + void virtio_queue_aio_set_host_notifier_handler(VirtQueue *vq, AioContext *ctx, VirtIOHandleOutput handle_output) { @@ -2078,6 +2095,9 @@ void virtio_queue_aio_set_host_notifier_handler(VirtQueue *vq, AioContext *ctx, aio_set_event_notifier(ctx, &vq->host_notifier, true, virtio_queue_host_notifier_aio_read, virtio_queue_host_notifier_aio_poll); + aio_set_event_notifier_poll(ctx, &vq->host_notifier, + virtio_queue_host_notifier_aio_poll_begin, + virtio_queue_host_notifier_aio_poll_end); } else { aio_set_event_notifier(ctx, &vq->host_notifier, true, NULL, NULL); /* Test and clear notifier before after disabling event, -- 2.7.4