On Tue, Jan 16, 2024 at 09:11:33PM +0800, Heng Qi wrote:
> Accumulate multiple request commands to kick the device once,
> and obtain the processing results of the corresponding commands
> asynchronously. The batch command method is used to optimize the
> CPU overhead of the DIM worker caused by the guest being busy
> waiting for the command response result.
>
> On an 8-queue device, without this patch, the guest cpu overhead
> due to waiting for cvq could be 10+% and above. With this patch,
> the corresponding overhead is basically invisible.
>
> Signed-off-by: Heng Qi <[email protected]>
...
> @@ -3520,22 +3568,99 @@ static int virtnet_send_notf_coal_vq_cmds(struct
> virtnet_info *vi,
> return 0;
> }
>
> +static bool virtnet_add_dim_command(struct virtnet_info *vi,
> + struct virtnet_batch_coal *ctrl)
> +{
> + struct scatterlist *sgs[4], hdr, stat, out;
> + unsigned out_num = 0;
> + int ret;
> +
> + /* Caller should know better */
> + BUG_ON(!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ));
> +
> + ctrl->hdr.class = VIRTIO_NET_CTRL_NOTF_COAL;
> + ctrl->hdr.cmd = VIRTIO_NET_CTRL_NOTF_COAL_VQS_SET;
> +
> + /* Add header */
> + sg_init_one(&hdr, &ctrl->hdr, sizeof(ctrl->hdr));
> + sgs[out_num++] = &hdr;
> +
> + /* Add body */
> + sg_init_one(&out, &ctrl->num_entries, sizeof(ctrl->num_entries) +
> + ctrl->num_entries * sizeof(struct virtnet_coal_entry));
Hi Heng Qi,
I am a bit confused.
With this series applied on top of net-next
struct virtnet_coal_entry doesn't seem to exist.
> + sgs[out_num++] = &out;
> +
> + /* Add return status. */
> + ctrl->status = VIRTIO_NET_OK;
> + sg_init_one(&stat, &ctrl->status, sizeof(ctrl->status));
> + sgs[out_num] = &stat;
> +
> + BUG_ON(out_num + 1 > ARRAY_SIZE(sgs));
> + ret = virtqueue_add_sgs(vi->cvq, sgs, out_num, 1, ctrl, GFP_ATOMIC);
> + if (ret < 0) {
> + dev_warn(&vi->vdev->dev, "Failed to add sgs for command vq:
> %d\n.", ret);
> + return false;
> + }
> +
> + virtqueue_kick(vi->cvq);
> +
> + ctrl->usable = false;
> + vi->cvq_cmd_nums++;
> +
> + return true;
> +}
...
