Re: [PATCH net-next v8] virtio/vsock: replace virtio_vsock_pkt with sk_buff
From: Stefano Garzarella
Date: Thu Dec 15 2022 - 03:49:07 EST
On Thu, Dec 15, 2022 at 04:36:44AM +0000, Bobby Eshleman wrote:
This commit changes virtio/vsock to use sk_buff instead of
virtio_vsock_pkt. Beyond better conforming to other net code, using
sk_buff allows vsock to use sk_buff-dependent features in the future
(such as sockmap) and improves throughput.
This patch introduces the following performance changes:
Tool/Config: uperf w/ 64 threads, SOCK_STREAM
Test Runs: 5, mean of results
Before: commit 95ec6bce2a0b ("Merge branch 'net-ipa-more-endpoints'")
Test: 64KB, g2h
Before: 21.63 Gb/s
After: 25.59 Gb/s (+18%)
Test: 16B, g2h
Before: 11.86 Mb/s
After: 17.41 Mb/s (+46%)
Test: 64KB, h2g
Before: 2.15 Gb/s
After: 3.6 Gb/s (+67%)
Test: 16B, h2g
Before: 14.38 Mb/s
After: 18.43 Mb/s (+28%)
Signed-off-by: Bobby Eshleman <bobby.eshleman@xxxxxxxxxxxxx>
---
Testing: passed vsock_test h2g and g2h
Note2: net-next is closed, but sending out now in case more comments
roll in, as discussed here:
https://lore.kernel.org/all/Y34SoH1nFTXXLWbK@bullseye/
Changes in v8:
- vhost/vsock: remove unused enum
- vhost/vsock: use spin_lock_bh() instead of spin_lock()
- vsock/loopback: use __skb_dequeue instead of skb_dequeue
Changes in v7:
- use skb_queue_empty() instead of skb_queue_empty_lockless()
Changes in v6:
- use skb->cb instead of skb->_skb_refdst
- use lock-free __skb_queue_purge for rx_queue when rx_lock held
Changes in v5:
- last_skb instead of skb: last_hdr->len = cpu_to_le32(last_skb->len)
Changes in v4:
- vdso/bits.h -> linux/bits.h
- add virtio_vsock_alloc_skb() helper
- virtio/vsock: rename buf_len -> total_len
- update last_hdr->len
- fix build_skb() for vsockmon (tested)
- add queue helpers
- use spin_{unlock/lock}_bh() instead of spin_lock()/spin_unlock()
- note: I only ran a few g2h tests to check that this change
had no perf impact. The above data is still from patch
v3.
Changes in v3:
- fix seqpacket bug
- use zero in vhost_add_used(..., 0) device doesn't write to buffer
- use xmas tree style declarations
- vsock_hdr() -> virtio_vsock_hdr() and other include file style fixes
- no skb merging
- save space by not using vsock_metadata
- use _skb_refdst instead of skb buffer space for flags
- use skb_pull() to keep track of read bytes instead of using an an
extra variable 'off' in the skb buffer space
- remove unnecessary sk_allocation assignment
- do not zero hdr needlessly
- introduce virtio_transport_skb_len() because skb->len changes now
- use spin_lock() directly on queue lock instead of sk_buff_head helpers
which use spin_lock_irqsave() (e.g., skb_dequeue)
- do not reduce buffer size to be page size divisible
- Note: the biggest performance change came from loosening the spinlock
variation and not reducing the buffer size.
Changes in v2:
- Use alloc_skb() directly instead of sock_alloc_send_pskb() to minimize
uAPI changes.
- Do not marshal errors to -ENOMEM for non-virtio implementations.
- No longer a part of the original series
- Some code cleanup and refactoring
- Include performance stats
drivers/vhost/vsock.c | 213 +++++-------
include/linux/virtio_vsock.h | 126 +++++--
net/vmw_vsock/virtio_transport.c | 149 +++------
net/vmw_vsock/virtio_transport_common.c | 422 +++++++++++++-----------
net/vmw_vsock/vsock_loopback.c | 51 +--
5 files changed, 495 insertions(+), 466 deletions(-)
diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 5703775af129..ee0a00432cb1 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -51,8 +51,7 @@ struct vhost_vsock {
struct hlist_node hash;
struct vhost_work send_pkt_work;
- spinlock_t send_pkt_list_lock;
- struct list_head send_pkt_list; /* host->guest pending packets */
+ struct sk_buff_head send_pkt_queue; /* host->guest pending packets */
atomic_t queued_replies;
@@ -108,40 +107,33 @@ vhost_transport_do_send_pkt(struct vhost_vsock
*vsock,
vhost_disable_notify(&vsock->dev, vq);
do {
- struct virtio_vsock_pkt *pkt;
+ struct virtio_vsock_hdr *hdr;
+ size_t iov_len, payload_len;
struct iov_iter iov_iter;
+ u32 flags_to_restore = 0;
+ struct sk_buff *skb;
unsigned out, in;
size_t nbytes;
- size_t iov_len, payload_len;
int head;
- u32 flags_to_restore = 0;
- spin_lock_bh(&vsock->send_pkt_list_lock);
- if (list_empty(&vsock->send_pkt_list)) {
- spin_unlock_bh(&vsock->send_pkt_list_lock);
+ spin_lock_bh(&vsock->send_pkt_queue.lock);
+ skb = __skb_dequeue(&vsock->send_pkt_queue);
+ spin_unlock_bh(&vsock->send_pkt_queue.lock);
Sorry for coming late, but I just commented in Paolo's reply.
Here I think we can directly use the new virtio_vsock_skb_dequeue().
With that fixed, you can put my R-b:
Reviewed-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
Below I left a little comment.
+
+ if (!skb) {
vhost_enable_notify(&vsock->dev, vq);
break;
}
- pkt = list_first_entry(&vsock->send_pkt_list,
- struct virtio_vsock_pkt, list);
- list_del_init(&pkt->list);
- spin_unlock_bh(&vsock->send_pkt_list_lock);
-
head = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
&out, &in, NULL, NULL);
if (head < 0) {
- spin_lock_bh(&vsock->send_pkt_list_lock);
- list_add(&pkt->list, &vsock->send_pkt_list);
- spin_unlock_bh(&vsock->send_pkt_list_lock);
+ virtio_vsock_skb_queue_head(&vsock->send_pkt_queue, skb);
break;
}
if (head == vq->num) {
- spin_lock_bh(&vsock->send_pkt_list_lock);
- list_add(&pkt->list, &vsock->send_pkt_list);
- spin_unlock_bh(&vsock->send_pkt_list_lock);
-
+ virtio_vsock_skb_queue_head(&vsock->send_pkt_queue, skb);
/* We cannot finish yet if more buffers snuck in while
* re-enabling notify.
*/
@@ -153,26 +145,27 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
}
if (out) {
- virtio_transport_free_pkt(pkt);
+ kfree_skb(skb);
vq_err(vq, "Expected 0 output buffers, got %u\n", out);
break;
}
iov_len = iov_length(&vq->iov[out], in);
- if (iov_len < sizeof(pkt->hdr)) {
- virtio_transport_free_pkt(pkt);
+ if (iov_len < sizeof(*hdr)) {
+ kfree_skb(skb);
vq_err(vq, "Buffer len [%zu] too small\n", iov_len);
break;
}
iov_iter_init(&iov_iter, READ, &vq->iov[out], in, iov_len);
- payload_len = pkt->len - pkt->off;
+ payload_len = skb->len;
+ hdr = virtio_vsock_hdr(skb);
/* If the packet is greater than the space available in the
* buffer, we split it using multiple buffers.
*/
- if (payload_len > iov_len - sizeof(pkt->hdr)) {
- payload_len = iov_len - sizeof(pkt->hdr);
+ if (payload_len > iov_len - sizeof(*hdr)) {
+ payload_len = iov_len - sizeof(*hdr);
/* As we are copying pieces of large packet's buffer to
* small rx buffers, headers of packets in rx queue are
@@ -185,31 +178,30 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
* bits set. After initialized header will be copied to
* rx buffer, these required bits will be restored.
*/
- if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_SEQ_EOM) {
- pkt->hdr.flags &= ~cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM);
+ if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SEQ_EOM) {
+ hdr->flags &= ~cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM);
flags_to_restore |= VIRTIO_VSOCK_SEQ_EOM;
- if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_SEQ_EOR) {
- pkt->hdr.flags &= ~cpu_to_le32(VIRTIO_VSOCK_SEQ_EOR);
+ if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SEQ_EOR) {
+ hdr->flags &= ~cpu_to_le32(VIRTIO_VSOCK_SEQ_EOR);
flags_to_restore |= VIRTIO_VSOCK_SEQ_EOR;
}
}
}
/* Set the correct length in the header */
- pkt->hdr.len = cpu_to_le32(payload_len);
+ hdr->len = cpu_to_le32(payload_len);
- nbytes = copy_to_iter(&pkt->hdr, sizeof(pkt->hdr), &iov_iter);
- if (nbytes != sizeof(pkt->hdr)) {
- virtio_transport_free_pkt(pkt);
+ nbytes = copy_to_iter(hdr, sizeof(*hdr), &iov_iter);
+ if (nbytes != sizeof(*hdr)) {
+ kfree_skb(skb);
vq_err(vq, "Faulted on copying pkt hdr\n");
break;
}
- nbytes = copy_to_iter(pkt->buf + pkt->off, payload_len,
- &iov_iter);
+ nbytes = copy_to_iter(skb->data, payload_len, &iov_iter);
if (nbytes != payload_len) {
- virtio_transport_free_pkt(pkt);
+ kfree_skb(skb);
vq_err(vq, "Faulted on copying pkt buf\n");
break;
}
@@ -217,31 +209,28 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
/* Deliver to monitoring devices all packets that we
* will transmit.
*/
- virtio_transport_deliver_tap_pkt(pkt);
+ virtio_transport_deliver_tap_pkt(skb);
- vhost_add_used(vq, head, sizeof(pkt->hdr) + payload_len);
+ vhost_add_used(vq, head, sizeof(*hdr) + payload_len);
added = true;
- pkt->off += payload_len;
+ skb_pull(skb, payload_len);
total_len += payload_len;
/* If we didn't send all the payload we can requeue the packet
* to send it with the next available buffer.
*/
- if (pkt->off < pkt->len) {
- pkt->hdr.flags |= cpu_to_le32(flags_to_restore);
+ if (skb->len > 0) {
+ hdr->flags |= cpu_to_le32(flags_to_restore);
- /* We are queueing the same virtio_vsock_pkt to handle
+ /* We are queueing the same skb to handle
* the remaining bytes, and we want to deliver it
* to monitoring devices in the next iteration.
*/
- pkt->tap_delivered = false;
-
- spin_lock_bh(&vsock->send_pkt_list_lock);
- list_add(&pkt->list, &vsock->send_pkt_list);
- spin_unlock_bh(&vsock->send_pkt_list_lock);
+ virtio_vsock_skb_clear_tap_delivered(skb);
+ virtio_vsock_skb_queue_head(&vsock->send_pkt_queue, skb);
} else {
- if (pkt->reply) {
+ if (virtio_vsock_skb_reply(skb)) {
int val;
val = atomic_dec_return(&vsock->queued_replies);
@@ -253,7 +242,7 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
restart_tx = true;
}
- virtio_transport_free_pkt(pkt);
+ consume_skb(skb);
}
} while(likely(!vhost_exceeds_weight(vq, ++pkts, total_len)));
if (added)
@@ -278,28 +267,26 @@ static void vhost_transport_send_pkt_work(struct vhost_work *work)
}
static int
-vhost_transport_send_pkt(struct virtio_vsock_pkt *pkt)
+vhost_transport_send_pkt(struct sk_buff *skb)
{
+ struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
struct vhost_vsock *vsock;
- int len = pkt->len;
+ int len = skb->len;
rcu_read_lock();
/* Find the vhost_vsock according to guest context id */
- vsock = vhost_vsock_get(le64_to_cpu(pkt->hdr.dst_cid));
+ vsock = vhost_vsock_get(le64_to_cpu(hdr->dst_cid));
if (!vsock) {
rcu_read_unlock();
- virtio_transport_free_pkt(pkt);
+ kfree_skb(skb);
return -ENODEV;
}
- if (pkt->reply)
+ if (virtio_vsock_skb_reply(skb))
atomic_inc(&vsock->queued_replies);
- spin_lock_bh(&vsock->send_pkt_list_lock);
- list_add_tail(&pkt->list, &vsock->send_pkt_list);
- spin_unlock_bh(&vsock->send_pkt_list_lock);
-
+ virtio_vsock_skb_queue_tail(&vsock->send_pkt_queue, skb);
vhost_work_queue(&vsock->dev, &vsock->send_pkt_work);
rcu_read_unlock();
@@ -310,10 +297,8 @@ static int
vhost_transport_cancel_pkt(struct vsock_sock *vsk)
{
struct vhost_vsock *vsock;
- struct virtio_vsock_pkt *pkt, *n;
int cnt = 0;
int ret = -ENODEV;
- LIST_HEAD(freeme);
rcu_read_lock();
@@ -322,20 +307,7 @@ vhost_transport_cancel_pkt(struct vsock_sock *vsk)
if (!vsock)
goto out;
- spin_lock_bh(&vsock->send_pkt_list_lock);
- list_for_each_entry_safe(pkt, n, &vsock->send_pkt_list, list) {
- if (pkt->vsk != vsk)
- continue;
- list_move(&pkt->list, &freeme);
- }
- spin_unlock_bh(&vsock->send_pkt_list_lock);
-
- list_for_each_entry_safe(pkt, n, &freeme, list) {
- if (pkt->reply)
- cnt++;
- list_del(&pkt->list);
- virtio_transport_free_pkt(pkt);
- }
+ cnt = virtio_transport_purge_skbs(vsk, &vsock->send_pkt_queue);
if (cnt) {
struct vhost_virtqueue *tx_vq = &vsock->vqs[VSOCK_VQ_TX];
@@ -352,12 +324,14 @@ vhost_transport_cancel_pkt(struct vsock_sock *vsk)
return ret;
}
-static struct virtio_vsock_pkt *
-vhost_vsock_alloc_pkt(struct vhost_virtqueue *vq,
+static struct sk_buff *
+vhost_vsock_alloc_skb(struct vhost_virtqueue *vq,
unsigned int out, unsigned int in)
{
- struct virtio_vsock_pkt *pkt;
+ struct virtio_vsock_hdr *hdr;
struct iov_iter iov_iter;
+ struct sk_buff *skb;
+ size_t payload_len;
size_t nbytes;
size_t len;
@@ -366,50 +340,47 @@ vhost_vsock_alloc_pkt(struct vhost_virtqueue *vq,
return NULL;
}
- pkt = kzalloc(sizeof(*pkt), GFP_KERNEL);
- if (!pkt)
+ len = iov_length(vq->iov, out);
+
+ /* len contains both payload and hdr */
+ skb = virtio_vsock_alloc_skb(len, GFP_KERNEL);
+ if (!skb)
return NULL;
- len = iov_length(vq->iov, out);
iov_iter_init(&iov_iter, WRITE, vq->iov, out, len);
- nbytes = copy_from_iter(&pkt->hdr, sizeof(pkt->hdr), &iov_iter);
- if (nbytes != sizeof(pkt->hdr)) {
+ hdr = virtio_vsock_hdr(skb);
+ nbytes = copy_from_iter(hdr, sizeof(*hdr), &iov_iter);
+ if (nbytes != sizeof(*hdr)) {
vq_err(vq, "Expected %zu bytes for pkt->hdr, got %zu bytes\n",
- sizeof(pkt->hdr), nbytes);
- kfree(pkt);
+ sizeof(*hdr), nbytes);
+ kfree_skb(skb);
return NULL;
}
- pkt->len = le32_to_cpu(pkt->hdr.len);
+ payload_len = le32_to_cpu(hdr->len);
/* No payload */
- if (!pkt->len)
- return pkt;
+ if (!payload_len)
+ return skb;
/* The pkt is too big */
- if (pkt->len > VIRTIO_VSOCK_MAX_PKT_BUF_SIZE) {
- kfree(pkt);
+ if (payload_len > VIRTIO_VSOCK_MAX_PKT_BUF_SIZE) {
+ kfree_skb(skb);
return NULL;
}
- pkt->buf = kvmalloc(pkt->len, GFP_KERNEL);
- if (!pkt->buf) {
- kfree(pkt);
- return NULL;
- }
+ virtio_vsock_skb_rx_put(skb);
- pkt->buf_len = pkt->len;
-
- nbytes = copy_from_iter(pkt->buf, pkt->len, &iov_iter);
- if (nbytes != pkt->len) {
- vq_err(vq, "Expected %u byte payload, got %zu bytes\n",
- pkt->len, nbytes);
- virtio_transport_free_pkt(pkt);
+ nbytes = copy_from_iter(skb->data, payload_len, &iov_iter);
+ if (nbytes != payload_len) {
+ vq_err(vq, "Expected %zu byte payload, got %zu bytes\n",
+ payload_len, nbytes);
+ kfree_skb(skb);
return NULL;
}
- return pkt;
+ return skb;
}
/* Is there space left for replies to rx packets? */
@@ -496,9 +467,9 @@ static void vhost_vsock_handle_tx_kick(struct vhost_work *work)
poll.work);
struct vhost_vsock *vsock = container_of(vq->dev, struct vhost_vsock,
dev);
- struct virtio_vsock_pkt *pkt;
int head, pkts = 0, total_len = 0;
unsigned int out, in;
+ struct sk_buff *skb;
bool added = false;
mutex_lock(&vq->mutex);
@@ -511,6 +482,8 @@ static void vhost_vsock_handle_tx_kick(struct vhost_work *work)
vhost_disable_notify(&vsock->dev, vq);
do {
+ struct virtio_vsock_hdr *hdr;
+
if (!vhost_vsock_more_replies(vsock)) {
/* Stop tx until the device processes already
* pending replies. Leave tx virtqueue
@@ -532,24 +505,26 @@ static void vhost_vsock_handle_tx_kick(struct vhost_work *work)
break;
}
- pkt = vhost_vsock_alloc_pkt(vq, out, in);
- if (!pkt) {
+ skb = vhost_vsock_alloc_skb(vq, out, in);
+ if (!skb) {
vq_err(vq, "Faulted on pkt\n");
continue;
}
- total_len += sizeof(pkt->hdr) + pkt->len;
+ total_len += sizeof(*hdr) + skb->len;
/* Deliver to monitoring devices all received packets */
- virtio_transport_deliver_tap_pkt(pkt);
+ virtio_transport_deliver_tap_pkt(skb);
+
+ hdr = virtio_vsock_hdr(skb);
/* Only accept correctly addressed packets */
- if (le64_to_cpu(pkt->hdr.src_cid) == vsock->guest_cid &&
- le64_to_cpu(pkt->hdr.dst_cid) ==
+ if (le64_to_cpu(hdr->src_cid) == vsock->guest_cid &&
+ le64_to_cpu(hdr->dst_cid) ==
vhost_transport_get_local_cid())
- virtio_transport_recv_pkt(&vhost_transport, pkt);
+ virtio_transport_recv_pkt(&vhost_transport, skb);
else
- virtio_transport_free_pkt(pkt);
+ kfree_skb(skb);
vhost_add_used(vq, head, 0);
added = true;
@@ -693,8 +668,7 @@ static int vhost_vsock_dev_open(struct inode *inode, struct file *file)
VHOST_VSOCK_WEIGHT, true, NULL);
file->private_data = vsock;
- spin_lock_init(&vsock->send_pkt_list_lock);
- INIT_LIST_HEAD(&vsock->send_pkt_list);
+ skb_queue_head_init(&vsock->send_pkt_queue);
vhost_work_init(&vsock->send_pkt_work, vhost_transport_send_pkt_work);
return 0;
@@ -760,16 +734,7 @@ static int vhost_vsock_dev_release(struct inode *inode, struct file *file)
vhost_vsock_flush(vsock);
vhost_dev_stop(&vsock->dev);
- spin_lock_bh(&vsock->send_pkt_list_lock);
- while (!list_empty(&vsock->send_pkt_list)) {
- struct virtio_vsock_pkt *pkt;
-
- pkt = list_first_entry(&vsock->send_pkt_list,
- struct virtio_vsock_pkt, list);
- list_del_init(&pkt->list);
- virtio_transport_free_pkt(pkt);
- }
- spin_unlock_bh(&vsock->send_pkt_list_lock);
+ virtio_vsock_skb_queue_purge(&vsock->send_pkt_queue);
vhost_dev_cleanup(&vsock->dev);
kfree(vsock->dev.vqs);
diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
index 35d7eedb5e8e..7ed943615271 100644
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -7,6 +7,106 @@
#include <net/sock.h>
#include <net/af_vsock.h>
+#define VIRTIO_VSOCK_SKB_HEADROOM (sizeof(struct virtio_vsock_hdr))
+
+struct virtio_vsock_skb_cb {
+ bool reply;
+ bool tap_delivered;
+};
+
+#define VIRTIO_VSOCK_SKB_CB(skb) ((struct virtio_vsock_skb_cb *)((skb)->cb))
+
+static inline struct virtio_vsock_hdr *virtio_vsock_hdr(struct sk_buff *skb)
+{
+ return (struct virtio_vsock_hdr *)skb->head;
+}
+
+static inline bool virtio_vsock_skb_reply(struct sk_buff *skb)
+{
+ return VIRTIO_VSOCK_SKB_CB(skb)->reply;
+}
+
+static inline void virtio_vsock_skb_set_reply(struct sk_buff *skb)
+{
+ VIRTIO_VSOCK_SKB_CB(skb)->reply = true;
+}
+
+static inline bool virtio_vsock_skb_tap_delivered(struct sk_buff *skb)
+{
+ return VIRTIO_VSOCK_SKB_CB(skb)->tap_delivered;
+}
+
+static inline void virtio_vsock_skb_set_tap_delivered(struct sk_buff *skb)
+{
+ VIRTIO_VSOCK_SKB_CB(skb)->tap_delivered = true;
+}
+
+static inline void virtio_vsock_skb_clear_tap_delivered(struct sk_buff *skb)
+{
+ VIRTIO_VSOCK_SKB_CB(skb)->tap_delivered = false;
+}
Maybe, we can have a single
virtio_vsock_skb_set_tap_delivered(struct sk_buff *skb,
bool tap_delivered)
to be used in both cases.
Anyway, I don't have a strong opinion on that.
Thanks,
Stefano