在 2023/11/22 下午1:52, Jason Wang 写道:
On Mon, Nov 20, 2023 at 8:38 PM Heng Qi <hengqi@xxxxxxxxxxxxxxxxx> wrote:
By comparing the traffic information in the complete napi processes,
let the virtio-net driver automatically adjust the coalescing
moderation parameters of each receive queue.
Signed-off-by: Heng Qi <hengqi@xxxxxxxxxxxxxxxxx>
---
v2->v3:
- Some minor modifications.
v1->v2:
- Improved the judgment of dim switch conditions.
- Cancel the work when vq reset.
drivers/net/virtio_net.c | 191 ++++++++++++++++++++++++++++++++++-----
1 file changed, 169 insertions(+), 22 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 69fe09e99b3c..bc32d5aae005 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -19,6 +19,7 @@
#include <linux/average.h>
#include <linux/filter.h>
#include <linux/kernel.h>
+#include <linux/dim.h>
#include <net/route.h>
#include <net/xdp.h>
#include <net/net_failover.h>
@@ -172,6 +173,17 @@ struct receive_queue {
struct virtnet_rq_stats stats;
+ /* The number of rx notifications */
+ u16 calls;
+
+ /* Is dynamic interrupt moderation enabled? */
+ bool dim_enabled;
+
+ /* Dynamic Interrupt Moderation */
+ struct dim dim;
+
+ u32 packets_in_napi;
+
struct virtnet_interrupt_coalesce intr_coal;
/* Chain pages by the private ptr. */
@@ -305,6 +317,9 @@ struct virtnet_info {
u8 duplex;
u32 speed;
+ /* Is rx dynamic interrupt moderation enabled? */
+ bool rx_dim_enabled;
+
/* Interrupt coalescing settings */
struct virtnet_interrupt_coalesce intr_coal_tx;
struct virtnet_interrupt_coalesce intr_coal_rx;
@@ -2001,6 +2016,7 @@ static void skb_recv_done(struct virtqueue *rvq)
struct virtnet_info *vi = rvq->vdev->priv;
struct receive_queue *rq = &vi->rq[vq2rxq(rvq)];
+ rq->calls++;
virtqueue_napi_schedule(&rq->napi, rvq);
}
@@ -2141,6 +2157,26 @@ static void virtnet_poll_cleantx(struct receive_queue *rq)
}
}
+static void virtnet_rx_dim_work(struct work_struct *work);
+
+static void virtnet_rx_dim_update(struct virtnet_info *vi, struct receive_queue *rq)
+{
+ struct dim_sample cur_sample = {};
+
+ if (!rq->packets_in_napi)
+ return;
+
+ u64_stats_update_begin(&rq->stats.syncp);
+ dim_update_sample(rq->calls,
+ u64_stats_read(&rq->stats.packets),
+ u64_stats_read(&rq->stats.bytes),
+ &cur_sample);
+ u64_stats_update_end(&rq->stats.syncp);
+
+ net_dim(&rq->dim, cur_sample);
+ rq->packets_in_napi = 0;
+}
+
static int virtnet_poll(struct napi_struct *napi, int budget)
{
struct receive_queue *rq =
@@ -2149,17 +2185,22 @@ static int virtnet_poll(struct napi_struct *napi, int budget)
struct send_queue *sq;
unsigned int received;
unsigned int xdp_xmit = 0;
+ bool napi_complete;
virtnet_poll_cleantx(rq);
received = virtnet_receive(rq, budget, &xdp_xmit);
+ rq->packets_in_napi += received;
if (xdp_xmit & VIRTIO_XDP_REDIR)
xdp_do_flush();
/* Out of packets? */
- if (received < budget)
- virtqueue_napi_complete(napi, rq->vq, received);
+ if (received < budget) {
+ napi_complete = virtqueue_napi_complete(napi, rq->vq, received);
+ if (napi_complete && rq->dim_enabled)
+ virtnet_rx_dim_update(vi, rq);
+ }
if (xdp_xmit & VIRTIO_XDP_TX) {
sq = virtnet_xdp_get_sq(vi);
@@ -2179,6 +2220,7 @@ static void virtnet_disable_queue_pair(struct virtnet_info *vi, int qp_index)
virtnet_napi_tx_disable(&vi->sq[qp_index].napi);
napi_disable(&vi->rq[qp_index].napi);
xdp_rxq_info_unreg(&vi->rq[qp_index].xdp_rxq);
+ cancel_work_sync(&vi->rq[qp_index].dim.work);
}
static int virtnet_enable_queue_pair(struct virtnet_info *vi, int qp_index)
@@ -2196,6 +2238,9 @@ static int virtnet_enable_queue_pair(struct virtnet_info *vi, int qp_index)
if (err < 0)
goto err_xdp_reg_mem_model;
+ INIT_WORK(&vi->rq[qp_index].dim.work, virtnet_rx_dim_work);
+ vi->rq[qp_index].dim.mode = DIM_CQ_PERIOD_MODE_START_FROM_EQE;
So in V2, you explained it can be done here but I want to know why it
must be done here.
It is not must be done here. We can place it in probe and make sure that
INIT_WORK() is
done before napi is enabled for the first time.
So then I'll don't call INIT_WORK() every time after "napi_disable ->
napi_enable" happens,
and use the following process:
Call INIT_WORK() in the driver probe and do cancel_work() after each
related napi_disable.
This will be clearer.
Additionally, Yinjun Zhang found that cancel_work_sync() will cause a
deadlock
when ndo_stop and virtnet_rx_dim_work occurs at the same time, so
cancel_work() will be used.
For example, the refill_work is initialized in alloc_queues().
+
virtnet_napi_enable(vi->rq[qp_index].vq, &vi->rq[qp_index].napi);
virtnet_napi_tx_enable(vi, vi->sq[qp_index].vq, &vi->sq[qp_index].napi);
@@ -2393,8 +2438,10 @@ static int virtnet_rx_resize(struct virtnet_info *vi,
qindex = rq - vi->rq;
- if (running)
+ if (running) {
napi_disable(&rq->napi);
+ cancel_work_sync(&rq->dim.work);
+ }
err = virtqueue_resize(rq->vq, ring_num, virtnet_rq_free_unused_buf);
if (err)
@@ -2403,8 +2450,10 @@ static int virtnet_rx_resize(struct virtnet_info *vi,
if (!try_fill_recv(vi, rq, GFP_KERNEL))
schedule_delayed_work(&vi->refill, 0);
- if (running)
+ if (running) {
+ INIT_WORK(&rq->dim.work, virtnet_rx_dim_work);
virtnet_napi_enable(rq->vq, &rq->napi);
+ }
return err;
}
@@ -3341,24 +3390,55 @@ static int virtnet_send_tx_notf_coal_cmds(struct virtnet_info *vi,
static int virtnet_send_rx_notf_coal_cmds(struct virtnet_info *vi,
struct ethtool_coalesce *ec)
{
+ bool rx_ctrl_dim_on = !!ec->use_adaptive_rx_coalesce;
+ bool update = false, switch_dim;
struct scatterlist sgs_rx;
int i;
- vi->ctrl->coal_rx.rx_usecs = cpu_to_le32(ec->rx_coalesce_usecs);
- vi->ctrl->coal_rx.rx_max_packets = cpu_to_le32(ec->rx_max_coalesced_frames);
- sg_init_one(&sgs_rx, &vi->ctrl->coal_rx, sizeof(vi->ctrl->coal_rx));
-
- if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_NOTF_COAL,
- VIRTIO_NET_CTRL_NOTF_COAL_RX_SET,
- &sgs_rx))
- return -EINVAL;
+ switch_dim = rx_ctrl_dim_on != vi->rx_dim_enabled;
+ if (switch_dim) {
+ if (rx_ctrl_dim_on) {
+ if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_VQ_NOTF_COAL)) {
So basically, I'm asking why we need to duplicate the check here?
Here is VIRTIO_NET_F_*VQ*_NOTF_COAL.
E.g caller has done the check for us:
if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL))
ret = virtnet_send_notf_coal_cmds(vi, ec);
else
ret = virtnet_coal_params_supported(ec);
?
Please also check other nested if/else, usually, too many levels of
nesting is a hint that the logic needs to be optimized.
I will optimize this.
Thanks!
Thanks
