From 6012ca8159a7f78e6fc5122a8e9f22d82e9723e9 Mon Sep 17 00:00:00 2001
From: Ming Lei <ming.lei@canonical.com>
Date: Wed, 12 Nov 2014 11:24:35 +0800
Subject: [PATCH] virtio-scsi: dataplane: suppress guest notification
This patch uses vring_should_notify() to suppress
guest notification, and looks notification frequency
can be decreased from ~33K/sec to ~2K/sec in my test
environment.
Suggested-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
hw/scsi/virtio-scsi-dataplane.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c
index 969b931557..03a1e8cfcf 100644
--- a/hw/scsi/virtio-scsi-dataplane.c
+++ b/hw/scsi/virtio-scsi-dataplane.c
@@ -92,9 +92,14 @@ VirtIOSCSIReq *virtio_scsi_pop_req_vring(VirtIOSCSI *s,
void virtio_scsi_vring_push_notify(VirtIOSCSIReq *req)
{
+ VirtIODevice *vdev = VIRTIO_DEVICE(req->vring->parent);
+
vring_push(&req->vring->vring, &req->elem,
req->qsgl.size + req->resp_iov.size);
- event_notifier_set(&req->vring->guest_notifier);
+
+ if (vring_should_notify(vdev, &req->vring->vring)) {
+ event_notifier_set(&req->vring->guest_notifier);
+ }
}
static void virtio_scsi_iothread_handle_ctrl(EventNotifier *notifier)