From: "sochin.jiang" <sochin.ji...@huawei.com>
Till now, we've already notify guest as a batch mostly, an
extra BH won't decrease guest interrupts much, but cause a
significant notification loss. Generally, we could have 15%
or so performance lost in single queue IO models, as I tested.
Signed-off-by: sochin.jiang <sochin.ji...@huawei.com>
---
hw/block/dataplane/virtio-blk.c | 19 +++++++------------
1 file changed, 7 insertions(+), 12 deletions(-)
diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c
index 5556f0e..a261a1d 100644
--- a/hw/block/dataplane/virtio-blk.c
+++ b/hw/block/dataplane/virtio-blk.c
@@ -32,7 +32,6 @@ struct VirtIOBlockDataPlane {
VirtIOBlkConf *conf;
VirtIODevice *vdev;
- QEMUBH *bh; /* bh for guest notification */
unsigned long *batch_notify_vqs;
/* Note that these EventNotifiers are assigned by value. This is
@@ -44,14 +43,7 @@ struct VirtIOBlockDataPlane {
AioContext *ctx;
};
-/* Raise an interrupt to signal guest, if necessary */
-void virtio_blk_data_plane_notify(VirtIOBlockDataPlane *s, VirtQueue *vq)
-{
- set_bit(virtio_get_queue_index(vq), s->batch_notify_vqs);
- qemu_bh_schedule(s->bh);
-}
-
-static void notify_guest_bh(void *opaque)
+static void notify_guest(void *opaque)
{
VirtIOBlockDataPlane *s = opaque;
unsigned nvqs = s->conf->num_queues;
@@ -75,7 +67,12 @@ static void notify_guest_bh(void *opaque)
}
}
-/* Context: QEMU global mutex held */
+/* Raise an interrupt to signal guest, if necessary */
+void virtio_blk_data_plane_notify(VirtIOBlockDataPlane *s, VirtQueue *vq)
+{
+ set_bit(virtio_get_queue_index(vq), s->batch_notify_vqs);
+ notify_guest(s);
+}
void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf,
VirtIOBlockDataPlane **dataplane,
Error **errp)
@@ -122,7 +119,6 @@ void virtio_blk_data_plane_create(VirtIODevice *vdev,
VirtIOBlkConf *conf,
} else {
s->ctx = qemu_get_aio_context();
}
- s->bh = aio_bh_new(s->ctx, notify_guest_bh, s);
s->batch_notify_vqs = bitmap_new(conf->num_queues);
*dataplane = s;
@@ -140,7 +136,6 @@ void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s)
vblk = VIRTIO_BLK(s->vdev);
assert(!vblk->dataplane_started);
g_free(s->batch_notify_vqs);
- qemu_bh_delete(s->bh);
if (s->iothread) {
object_unref(OBJECT(s->iothread));
}
--
1.8.3.1
