Mon, Jun 17, 2024 at 04:34:26AM CEST, jasowang@xxxxxxxxxx wrote:
>On Thu, Jun 13, 2024 at 1:09 AM Jiri Pirko <jiri@xxxxxxxxxxx> wrote:
>>
>> From: Jiri Pirko <jiri@xxxxxxxxxx>
>>
>> Add support for Byte Queue Limits (BQL).
>>
>> Tested on qemu emulated virtio_net device with 1, 2 and 4 queues.
>> Tested with fq_codel and pfifo_fast. Super netperf with 50 threads is
>> running in background. Netperf TCP_RR results:
>>
>> NOBQL FQC 1q: 159.56 159.33 158.50 154.31 agv: 157.925
>> NOBQL FQC 2q: 184.64 184.96 174.73 174.15 agv: 179.62
>> NOBQL FQC 4q: 994.46 441.96 416.50 499.56 agv: 588.12
>> NOBQL PFF 1q: 148.68 148.92 145.95 149.48 agv: 148.2575
>> NOBQL PFF 2q: 171.86 171.20 170.42 169.42 agv: 170.725
>> NOBQL PFF 4q: 1505.23 1137.23 2488.70 3507.99 agv: 2159.7875
>> BQL FQC 1q: 1332.80 1297.97 1351.41 1147.57 agv: 1282.4375
>> BQL FQC 2q: 768.30 817.72 864.43 974.40 agv: 856.2125
>> BQL FQC 4q: 945.66 942.68 878.51 822.82 agv: 897.4175
>> BQL PFF 1q: 149.69 151.49 149.40 147.47 agv: 149.5125
>> BQL PFF 2q: 2059.32 798.74 1844.12 381.80 agv: 1270.995
>> BQL PFF 4q: 1871.98 4420.02 4916.59 13268.16 agv: 6119.1875
>>
>> Signed-off-by: Jiri Pirko <jiri@xxxxxxxxxx>
>> ---
>> v1->v2:
>> - moved netdev_tx_completed_queue() call into __free_old_xmit(),
>> propagate use_napi flag to __free_old_xmit() and only call
>> netdev_tx_completed_queue() in case it is true
>> - added forgotten call to netdev_tx_reset_queue()
>> - fixed stats for xdp packets
>> - fixed bql accounting when __free_old_xmit() is called from xdp path
>> - handle the !use_napi case in start_xmit() kick section
>> ---
>> drivers/net/virtio_net.c | 50 +++++++++++++++++++++++++---------------
>> 1 file changed, 32 insertions(+), 18 deletions(-)
>>
>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
>> index 61a57d134544..5863c663ccab 100644
>> --- a/drivers/net/virtio_net.c
>> +++ b/drivers/net/virtio_net.c
>> @@ -84,7 +84,9 @@ struct virtnet_stat_desc {
>>
>> struct virtnet_sq_free_stats {
>> u64 packets;
>> + u64 xdp_packets;
>> u64 bytes;
>> + u64 xdp_bytes;
>> };
>>
>> struct virtnet_sq_stats {
>> @@ -506,29 +508,33 @@ static struct xdp_frame *ptr_to_xdp(void *ptr)
>> return (struct xdp_frame *)((unsigned long)ptr & ~VIRTIO_XDP_FLAG);
>> }
>>
>> -static void __free_old_xmit(struct send_queue *sq, bool in_napi,
>> +static void __free_old_xmit(struct send_queue *sq, struct netdev_queue *txq,
>> + bool in_napi, bool use_napi,
>> struct virtnet_sq_free_stats *stats)
>> {
>> unsigned int len;
>> void *ptr;
>>
>> while ((ptr = virtqueue_get_buf(sq->vq, &len)) != NULL) {
>> - ++stats->packets;
>> -
>> if (!is_xdp_frame(ptr)) {
>> struct sk_buff *skb = ptr;
>>
>> pr_debug("Sent skb %p\n", skb);
>>
>> + stats->packets++;
>> stats->bytes += skb->len;
>> napi_consume_skb(skb, in_napi);
>> } else {
>> struct xdp_frame *frame = ptr_to_xdp(ptr);
>>
>> - stats->bytes += xdp_get_frame_len(frame);
>> + stats->xdp_packets++;
>> + stats->xdp_bytes += xdp_get_frame_len(frame);
>> xdp_return_frame(frame);
>> }
>> }
>> + if (use_napi)
>> + netdev_tx_completed_queue(txq, stats->packets, stats->bytes);
>> +
>> }
>
>I wonder if this works correctly, for example NAPI could be enabled
>after queued but before sent. So __netdev_tx_sent_queue() is not
>called before.
How is that possible? Napi weight can't change when link is up. Or am I
missing something?
>
>Thanks
>
