[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [PATCH v1 2/2] virtio-scsi: dataplane: notify guest as batc
From: |
Ming Lei |
Subject: |
[Qemu-devel] [PATCH v1 2/2] virtio-scsi: dataplane: notify guest as batch |
Date: |
Tue, 11 Nov 2014 09:17:10 +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 | 26 +++++++++++++++++++++++++-
include/hw/virtio/virtio-scsi.h | 4 ++++
3 files changed, 32 insertions(+), 2 deletions(-)
diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c
index df17229..294515a 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..98411ef 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");
@@ -824,7 +839,12 @@ void virtio_scsi_common_realize(DeviceState *dev, Error
**errp,
}
if (s->conf.iothread) {
- virtio_scsi_set_iothread(VIRTIO_SCSI(s), s->conf.iothread);
+ VirtIOSCSI *vis = VIRTIO_SCSI(s);
+
+ QEMU_BUILD_BUG_ON(VIRTIO_PCI_QUEUE_MAX > 64);
+ virtio_scsi_set_iothread(vis, s->conf.iothread);
+ vis->pending_guest_notify = 0;
+ vis->guest_notify_bh = aio_bh_new(vis->ctx, notify_guest_bh, vis);
}
}
@@ -901,7 +921,11 @@ void virtio_scsi_common_unrealize(DeviceState *dev, Error
**errp)
{
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(dev);
+ VirtIOSCSI *s = VIRTIO_SCSI(vs);
+ if (vs->conf.iothread) {
+ qemu_bh_delete(s->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