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Date: Wed, 3 May 2017 16:01:16 -0700
From: Stephen Hemminger <stephen@...workplumber.org>
To: davem@...emloft.net
Cc: netdev@...r.kernel.org, Stephen Hemminger <sthemmin@...rosoft.com>
Subject: [PATCH net-next 14/15] netvsc: optimize receive completions
Handle receive completions better:
* format message directly in ring rather than in different bookkeeping structure
* eliminate atomic operation
* get rid of modulus (divide) on ring wrap
* avoid potential stall if ring gets full
* don't make ring element opaque
Signed-off-by: Stephen Hemminger <sthemmin@...rosoft.com>
---
drivers/net/hyperv/hyperv_net.h | 16 +++-
drivers/net/hyperv/netvsc.c | 168 +++++++++++---------------------------
drivers/net/hyperv/rndis_filter.c | 11 +--
3 files changed, 64 insertions(+), 131 deletions(-)
diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index 29555317ca05..a4417100a040 100644
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -650,16 +650,24 @@ struct multi_send_data {
struct recv_comp_data {
u64 tid; /* transaction id */
- u32 status;
+ struct {
+ struct nvsp_message_header hdr;
+ u32 status;
+ } msg __packed;
};
struct multi_recv_comp {
- void *buf; /* queued receive completions */
- u32 first; /* first data entry */
- u32 next; /* next entry for writing */
+ struct recv_comp_data *ring;
+ u32 read;
+ u32 write;
u32 size; /* number of slots in ring */
};
+static inline bool recv_complete_ring_empty(const struct multi_recv_comp *mrc)
+{
+ return mrc->read == mrc->write;
+}
+
struct netvsc_stats {
u64 packets;
u64 bytes;
diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index eb9f3e517fa5..2938f1a2b765 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -72,8 +72,8 @@ static struct netvsc_device *alloc_net_device(u32 recvslot_max)
mrc = &net_device->chan_table[0].mrc;
mrc->size = recvslot_max;
- mrc->buf = vzalloc(recvslot_max * sizeof(struct recv_comp_data));
- if (!mrc->buf) {
+ mrc->ring = vzalloc(recvslot_max * sizeof(struct recv_comp_data));
+ if (!mrc->ring) {
kfree(net_device);
return NULL;
}
@@ -96,7 +96,7 @@ static void free_netvsc_device(struct rcu_head *head)
int i;
for (i = 0; i < VRSS_CHANNEL_MAX; i++)
- vfree(nvdev->chan_table[i].mrc.buf);
+ vfree(nvdev->chan_table[i].mrc.ring);
kfree(nvdev);
}
@@ -974,120 +974,51 @@ int netvsc_send(struct hv_device *device,
return ret;
}
-static int netvsc_send_recv_completion(struct vmbus_channel *channel,
- u64 transaction_id, u32 status)
-{
- struct nvsp_message recvcompMessage;
- int ret;
-
- recvcompMessage.hdr.msg_type =
- NVSP_MSG1_TYPE_SEND_RNDIS_PKT_COMPLETE;
-
- recvcompMessage.msg.v1_msg.send_rndis_pkt_complete.status = status;
-
- /* Send the completion */
- ret = vmbus_sendpacket(channel, &recvcompMessage,
- sizeof(struct nvsp_message_header) + sizeof(u32),
- transaction_id, VM_PKT_COMP, 0);
-
- return ret;
-}
-
-static inline void count_recv_comp_slot(struct netvsc_device *nvdev, u16 q_idx,
- u32 *filled, u32 *avail)
-{
- struct multi_recv_comp *mrc = &nvdev->chan_table[q_idx].mrc;
- u32 first = mrc->first;
- u32 next = mrc->next;
-
- *filled = (first > next) ? mrc->size - first + next :
- next - first;
-
- *avail = mrc->size - *filled - 1;
-}
-/* Read the first filled slot, no change to index */
-static inline struct recv_comp_data *read_recv_comp_slot(struct netvsc_device
- *nvdev, u16 q_idx)
+/* Check and send pending recv completions */
+static int send_receive_comp(struct netvsc_device *nvdev,
+ struct vmbus_channel *channel, u16 q_idx)
{
struct multi_recv_comp *mrc = &nvdev->chan_table[q_idx].mrc;
- u32 filled, avail;
- if (unlikely(!mrc->buf))
- return NULL;
+ while (!recv_complete_ring_empty(mrc)) {
+ struct recv_comp_data *rcd = mrc->ring + mrc->read;
+ int ret;
- count_recv_comp_slot(nvdev, q_idx, &filled, &avail);
- if (!filled)
- return NULL;
+ ret = vmbus_sendpacket(channel, &rcd->msg, sizeof(rcd->msg),
+ rcd->tid, VM_PKT_COMP, 0);
- return mrc->buf + mrc->first * sizeof(struct recv_comp_data);
-}
+ /* if ring to host gets full, retry later */
+ if (unlikely(ret != 0))
+ return ret;
-/* Put the first filled slot back to available pool */
-static inline void put_recv_comp_slot(struct netvsc_device *nvdev, u16 q_idx)
-{
- struct multi_recv_comp *mrc = &nvdev->chan_table[q_idx].mrc;
- int num_recv;
-
- mrc->first = (mrc->first + 1) % mrc->size;
-
- num_recv = atomic_dec_return(&nvdev->num_outstanding_recvs);
+ if (++mrc->read == mrc->size)
+ mrc->read = 0;
+ }
- if (nvdev->destroy && num_recv == 0)
+ /* ring now empty */
+ if (unlikely(nvdev->destroy))
wake_up(&nvdev->wait_drain);
+ return 0;
}
-/* Check and send pending recv completions */
-static void netvsc_chk_recv_comp(struct netvsc_device *nvdev,
- struct vmbus_channel *channel, u16 q_idx)
-{
- struct recv_comp_data *rcd;
- int ret;
-
- while (true) {
- rcd = read_recv_comp_slot(nvdev, q_idx);
- if (!rcd)
- break;
-
- ret = netvsc_send_recv_completion(channel, rcd->tid,
- rcd->status);
- if (ret)
- break;
-
- put_recv_comp_slot(nvdev, q_idx);
- }
-}
-
-#define NETVSC_RCD_WATERMARK 80
-
/* Get next available slot */
-static inline struct recv_comp_data *get_recv_comp_slot(
- struct netvsc_device *nvdev, struct vmbus_channel *channel, u16 q_idx)
+static struct recv_comp_data *
+get_recv_comp_slot(struct netvsc_device *nvdev,
+ struct vmbus_channel *channel, u16 q_idx)
{
struct multi_recv_comp *mrc = &nvdev->chan_table[q_idx].mrc;
- u32 filled, avail, next;
struct recv_comp_data *rcd;
+ u32 next = mrc->write;
- if (unlikely(!nvdev->recv_section))
- return NULL;
-
- if (unlikely(!mrc->buf))
- return NULL;
-
- if (atomic_read(&nvdev->num_outstanding_recvs) >
- nvdev->recv_section->num_sub_allocs * NETVSC_RCD_WATERMARK / 100)
- netvsc_chk_recv_comp(nvdev, channel, q_idx);
+ if (++next == mrc->size)
+ next = 0;
- count_recv_comp_slot(nvdev, q_idx, &filled, &avail);
- if (!avail)
+ if (unlikely(next == mrc->read))
return NULL;
- next = mrc->next;
- rcd = mrc->buf + next * sizeof(struct recv_comp_data);
- mrc->next = (next + 1) % mrc->size;
-
- atomic_inc(&nvdev->num_outstanding_recvs);
-
+ rcd = mrc->ring + mrc->write;
+ mrc->write = next;
return rcd;
}
@@ -1104,9 +1035,8 @@ static int netvsc_receive(struct net_device *ndev,
u16 q_idx = channel->offermsg.offer.sub_channel_index;
char *recv_buf = net_device->recv_buf;
u32 status = NVSP_STAT_SUCCESS;
- int i;
- int count = 0;
- int ret;
+ struct recv_comp_data *rcd;
+ int i, count = 0;
/* Make sure this is a valid nvsp packet */
if (unlikely(nvsp->hdr.msg_type != NVSP_MSG1_TYPE_SEND_RNDIS_PKT)) {
@@ -1137,25 +1067,16 @@ static int netvsc_receive(struct net_device *ndev,
channel, data, buflen);
}
- if (net_device->chan_table[q_idx].mrc.buf) {
- struct recv_comp_data *rcd;
-
- rcd = get_recv_comp_slot(net_device, channel, q_idx);
- if (rcd) {
- rcd->tid = vmxferpage_packet->d.trans_id;
- rcd->status = status;
- } else {
- netdev_err(ndev, "Recv_comp full buf q:%hd, tid:%llx\n",
- q_idx, vmxferpage_packet->d.trans_id);
- }
+ rcd = get_recv_comp_slot(net_device, channel, q_idx);
+ if (likely(rcd)) {
+ rcd->tid = vmxferpage_packet->d.trans_id;
+ rcd->msg.hdr.msg_type = NVSP_MSG1_TYPE_SEND_RNDIS_PKT_COMPLETE;
+ rcd->msg.status = status;
} else {
- ret = netvsc_send_recv_completion(channel,
- vmxferpage_packet->d.trans_id,
- status);
- if (ret)
- netdev_err(ndev, "Recv_comp q:%hd, tid:%llx, err:%d\n",
- q_idx, vmxferpage_packet->d.trans_id, ret);
+ netdev_err(ndev, "Recv_comp full buf q:%hd, tid:%llx\n",
+ q_idx, vmxferpage_packet->d.trans_id);
}
+
return count;
}
@@ -1258,6 +1179,9 @@ int netvsc_poll(struct napi_struct *napi, int budget)
struct netvsc_device *net_device = net_device_to_netvsc_device(ndev);
int work_done = 0;
+ /* If ring has leftover completions flush them now */
+ send_receive_comp(net_device, channel, q_idx);
+
/* If starting a new interval */
if (!nvchan->desc)
nvchan->desc = hv_pkt_iter_first(channel);
@@ -1270,14 +1194,14 @@ int netvsc_poll(struct napi_struct *napi, int budget)
hv_pkt_iter_close(channel);
- netvsc_chk_recv_comp(net_device, channel, q_idx);
-
- /* If receive ring was exhausted
+ /* If all receive completions sent to host
+ * and budget was not used up
* and not doing busy poll
* then re-enable host interrupts
* and reschedule if ring is not empty.
*/
- if (work_done < budget &&
+ if (send_receive_comp(net_device, channel, q_idx) == 0 &&
+ work_done < budget &&
napi_complete_done(napi, work_done) &&
hv_end_read(&channel->inbound) != 0) {
/* special case if new messages are available */
diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c
index 2a89bbd6e42b..1b8ce9bc0ce7 100644
--- a/drivers/net/hyperv/rndis_filter.c
+++ b/drivers/net/hyperv/rndis_filter.c
@@ -901,12 +901,12 @@ static bool netvsc_device_idle(const struct netvsc_device *nvdev)
{
int i;
- if (atomic_read(&nvdev->num_outstanding_recvs) > 0)
- return false;
-
for (i = 0; i < nvdev->num_chn; i++) {
const struct netvsc_channel *nvchan = &nvdev->chan_table[i];
+ if (!recv_complete_ring_empty(&nvchan->mrc))
+ return false;
+
if (atomic_read(&nvchan->queue_sends) > 0)
return false;
}
@@ -997,8 +997,9 @@ static void netvsc_sc_open(struct vmbus_channel *new_sc)
nvchan = nvscdev->chan_table + chn_index;
nvchan->mrc.size = nvscdev->recv_buf_size / ETH_DATA_LEN + 1;
- nvchan->mrc.buf = vzalloc(nvchan->mrc.size * sizeof(struct recv_comp_data));
- if (!nvchan->mrc.buf)
+ nvchan->mrc.ring = vzalloc(nvchan->mrc.size
+ * sizeof(struct recv_comp_data));
+ if (!nvchan->mrc.ring)
return;
/* Because the device uses NAPI, all the interrupt batching and
--
2.11.0
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