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[Qemu-devel] [PATCH 2/2] virtio-scsi-dataplane: notify guest as batch
From: |
Ming Lei |
Subject: |
[Qemu-devel] [PATCH 2/2] virtio-scsi-dataplane: notify guest as batch |
Date: |
Sun, 9 Nov 2014 23:50:18 +0800 |
It isn't necessery to notify guest each time when one request
is completed, and it should be enough to just notify one time
for each running of virtio_scsi_iothread_handle_cmd().
This patch supresses about 30K/sec write on eventfd.
Signed-off-by: Ming Lei <address@hidden>
---
hw/scsi/virtio-scsi-dataplane.c | 4 +++-
hw/scsi/virtio-scsi.c | 22 ++++++++++++++++++++++
include/hw/virtio/virtio-scsi.h | 4 ++++
3 files changed, 29 insertions(+), 1 deletion(-)
diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c
index 8a7cd9f..1fb83de 100644
--- a/hw/scsi/virtio-scsi-dataplane.c
+++ b/hw/scsi/virtio-scsi-dataplane.c
@@ -62,6 +62,7 @@ static VirtIOSCSIVring *virtio_scsi_vring_init(VirtIOSCSI *s,
aio_set_event_notifier(s->ctx, &r->host_notifier, handler);
r->parent = s;
+ r->qid = n;
if (!vring_setup(&r->vring, VIRTIO_DEVICE(s), n)) {
fprintf(stderr, "virtio-scsi: VRing setup failed\n");
@@ -95,7 +96,8 @@ void virtio_scsi_vring_push_notify(VirtIOSCSIReq *req)
{
vring_push(&req->vring->vring, &req->elem,
req->qsgl.size + req->resp_iov.size);
- event_notifier_set(&req->vring->guest_notifier);
+ req->dev->pending_guest_notify |= 1 << (req->vring->qid - 2);
+ qemu_bh_schedule(req->dev->guest_notify_bh);
}
static void virtio_scsi_iothread_handle_ctrl(EventNotifier *notifier)
diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index 6e34a2c..1b9c35c 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -86,6 +86,21 @@ static void virtio_scsi_complete_req(VirtIOSCSIReq *req)
virtio_scsi_free_req(req);
}
+static void notify_guest_bh(void *opaque)
+{
+ VirtIOSCSI *s = opaque;
+ unsigned int qid;
+ uint64_t pending = s->pending_guest_notify;
+
+ s->pending_guest_notify = 0;
+
+ while ((qid = ffsl(pending))) {
+ qid--;
+ event_notifier_set(&s->cmd_vrings[qid]->guest_notifier);
+ pending &= ~(1 << qid);
+ }
+}
+
static void virtio_scsi_bad_req(void)
{
error_report("wrong size for virtio-scsi headers");
@@ -825,6 +840,10 @@ void virtio_scsi_common_realize(DeviceState *dev, Error
**errp,
if (s->conf.iothread) {
virtio_scsi_set_iothread(VIRTIO_SCSI(s), s->conf.iothread);
+ VIRTIO_SCSI(s)->pending_guest_notify = 0;
+ VIRTIO_SCSI(s)->guest_notify_bh = aio_bh_new(VIRTIO_SCSI(s)->ctx,
+ notify_guest_bh,
+ VIRTIO_SCSI(s));
}
}
@@ -902,6 +921,9 @@ void virtio_scsi_common_unrealize(DeviceState *dev, Error
**errp)
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(dev);
+ if (vs->conf.iothread) {
+ qemu_bh_delete(VIRTIO_SCSI(vs)->guest_notify_bh);
+ }
g_free(vs->cmd_vqs);
virtio_cleanup(vdev);
}
diff --git a/include/hw/virtio/virtio-scsi.h b/include/hw/virtio/virtio-scsi.h
index 9e1a49c..5e6c57e 100644
--- a/include/hw/virtio/virtio-scsi.h
+++ b/include/hw/virtio/virtio-scsi.h
@@ -163,6 +163,7 @@ typedef struct {
Vring vring;
EventNotifier host_notifier;
EventNotifier guest_notifier;
+ uint32_t qid;
} VirtIOSCSIVring;
typedef struct VirtIOSCSICommon {
@@ -198,6 +199,9 @@ typedef struct VirtIOSCSI {
bool dataplane_fenced;
Error *blocker;
Notifier migration_state_notifier;
+
+ QEMUBH *guest_notify_bh;
+ uint64_t pending_guest_notify;
} VirtIOSCSI;
typedef struct VirtIOSCSIReq {
--
1.7.9.5
[Qemu-devel] [PATCH 2/2] virtio-scsi-dataplane: notify guest as batch,
Ming Lei <=