From: Junjie Chen <junjie.j.chen@intel.com>
To: yliu@fridaylinux.org, maxime.coquelin@redhat.com,
xiao.w.wang@intel.com, tiwei.bie@intel.com, lei.a.yao@intel.com
Cc: dev@dpdk.org, Junjie Chen <junjie.j.chen@intel.com>
Subject: [dpdk-dev] [PATCH v7] vhost: support virtqueue interrupt/notification suppression
Date: Tue, 9 Jan 2018 06:03:48 -0500 [thread overview]
Message-ID: <1515495828-190409-1-git-send-email-junjie.j.chen@intel.com> (raw)
In-Reply-To: <1514310190-140916-1-git-send-email-junjie.j.chen@intel.com>
The driver can suppress interrupt when VIRTIO_F_EVENT_IDX feature bit is
negotiated. The driver set vring flags to 0, and MAY use used_event in
available ring to advise device interrupt util reach an index specified
by used_event. The device ignore the lower bit of vring flags, and send
an interrupt when index reach used_event.
The device can suppress notification in a manner analogous to the ways
driver suppress interrupt. The device manipulates flags or avail_event in
the used ring in the same way the driver manipulates flags or used_event in
available ring.
Signed-off-by: Junjie Chen <junjie.j.chen@intel.com>
---
v7:
Add vhost_need_event definition and update code for next virtio.
v6:
Use volatile qualifier to access avail event idx.
v5:
Remove updating avail event index in backend.
v2-v4:
Use definition of VIRTIO_F_EVENT_IDX from kernel.
lib/librte_vhost/vhost.c | 2 +-
lib/librte_vhost/vhost.h | 44 ++++++++++++++++++++++++++++++++++++++-----
lib/librte_vhost/virtio_net.c | 6 +++---
3 files changed, 43 insertions(+), 9 deletions(-)
diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c
index 6f7ef7f..400caa0 100644
--- a/lib/librte_vhost/vhost.c
+++ b/lib/librte_vhost/vhost.c
@@ -538,7 +538,7 @@ rte_vhost_vring_call(int vid, uint16_t vring_idx)
if (!vq)
return -1;
- vhost_vring_call(vq);
+ vhost_vring_call(dev, vq);
return 0;
}
diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
index 1d9366e..ec79991 100644
--- a/lib/librte_vhost/vhost.h
+++ b/lib/librte_vhost/vhost.h
@@ -103,6 +103,8 @@ struct vhost_virtqueue {
uint16_t last_avail_idx;
uint16_t last_used_idx;
+ /* Last used index we notify to front end. */
+ uint16_t signalled_used;
#define VIRTIO_INVALID_EVENTFD (-1)
#define VIRTIO_UNINITIALIZED_EVENTFD (-2)
@@ -214,6 +216,7 @@ struct vhost_msg {
(1ULL << VIRTIO_NET_F_GUEST_TSO6) | \
(1ULL << VIRTIO_NET_F_GUEST_UFO) | \
(1ULL << VIRTIO_RING_F_INDIRECT_DESC) | \
+ (1ULL << VIRTIO_RING_F_EVENT_IDX) | \
(1ULL << VIRTIO_NET_F_MTU) | \
(1ULL << VIRTIO_F_IOMMU_PLATFORM))
@@ -399,16 +402,47 @@ vhost_iova_to_vva(struct virtio_net *dev, struct vhost_virtqueue *vq,
return __vhost_iova_to_vva(dev, vq, iova, size, perm);
}
+#define vhost_used_event(vr) \
+ (*(volatile uint16_t*)&(vr)->avail->ring[(vr)->size])
+
+/*
+ * The following is used with VIRTIO_RING_F_EVENT_IDX.
+ * Assuming a given event_idx value from the other size, if we have
+ * just incremented index from old to new_idx, should we trigger an
+ * event?
+ */
+static __rte_always_inline int
+vhost_need_event(uint16_t event_idx, uint16_t new_idx, uint16_t old)
+{
+ return (uint16_t)(new_idx - event_idx - 1) < (uint16_t)(new_idx - old);
+}
+
static __rte_always_inline void
-vhost_vring_call(struct vhost_virtqueue *vq)
+vhost_vring_call(struct virtio_net *dev, struct vhost_virtqueue *vq)
{
/* Flush used->idx update before we read avail->flags. */
rte_mb();
- /* Kick the guest if necessary. */
- if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
- && (vq->callfd >= 0))
- eventfd_write(vq->callfd, (eventfd_t)1);
+ /* Don't kick guest if we don't reach index specified by guest. */
+ if (dev->features & (1ULL << VIRTIO_RING_F_EVENT_IDX)) {
+ uint16_t old = vq->signalled_used;
+ uint16_t new = vq->last_used_idx;
+
+ LOG_DEBUG(VHOST_DATA, "%s: used_event_idx=%d, old=%d, new=%d\n",
+ __func__,
+ vhost_used_event(vq),
+ old, new);
+ if (vhost_need_event(vhost_used_event(vq), new, old)
+ && (vq->callfd >= 0)) {
+ vq->signalled_used = vq->last_used_idx;
+ eventfd_write(vq->callfd, (eventfd_t) 1);
+ }
+ } else {
+ /* Kick the guest if necessary. */
+ if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
+ && (vq->callfd >= 0))
+ eventfd_write(vq->callfd, (eventfd_t)1);
+ }
}
#endif /* _VHOST_NET_CDEV_H_ */
diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
index eb496e1..d0f9221 100644
--- a/lib/librte_vhost/virtio_net.c
+++ b/lib/librte_vhost/virtio_net.c
@@ -413,7 +413,7 @@ virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
offsetof(struct vring_used, idx),
sizeof(vq->used->idx));
- vhost_vring_call(vq);
+ vhost_vring_call(dev, vq);
out:
if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))
vhost_user_iotlb_rd_unlock(vq);
@@ -700,7 +700,7 @@ virtio_dev_merge_rx(struct virtio_net *dev, uint16_t queue_id,
if (likely(vq->shadow_used_idx)) {
flush_shadow_used_ring(dev, vq);
- vhost_vring_call(vq);
+ vhost_vring_call(dev, vq);
}
out:
@@ -1104,7 +1104,7 @@ update_used_idx(struct virtio_net *dev, struct vhost_virtqueue *vq,
vq->used->idx += count;
vhost_log_used_vring(dev, vq, offsetof(struct vring_used, idx),
sizeof(vq->used->idx));
- vhost_vring_call(vq);
+ vhost_vring_call(dev, vq);
}
static __rte_always_inline struct zcopy_mbuf *
--
2.0.1
next prev parent reply other threads:[~2018-01-09 3:23 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-28 11:02 [dpdk-dev] [PATCH v4] " junjie.j.chen
2017-12-23 16:55 ` [dpdk-dev] [PATCH v5] " Junjie Chen
2017-12-26 8:03 ` Wang, Xiao W
2017-12-26 17:43 ` [dpdk-dev] [PATCH v6] " Junjie Chen
2018-01-05 5:25 ` Wang, Xiao W
2018-01-08 14:06 ` Yuanhan Liu
2018-01-09 2:12 ` Chen, Junjie J
2018-01-09 2:29 ` Yuanhan Liu
2018-01-09 11:03 ` Junjie Chen [this message]
2018-01-09 7:34 ` [dpdk-dev] [PATCH v7] " Yao, Lei A
2018-01-09 12:58 ` Yuanhan Liu
2018-01-09 8:56 ` Maxime Coquelin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1515495828-190409-1-git-send-email-junjie.j.chen@intel.com \
--to=junjie.j.chen@intel.com \
--cc=dev@dpdk.org \
--cc=lei.a.yao@intel.com \
--cc=maxime.coquelin@redhat.com \
--cc=tiwei.bie@intel.com \
--cc=xiao.w.wang@intel.com \
--cc=yliu@fridaylinux.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).