Re: [PATCH net-next 6/6] tools: virtio: introduce vhost_net_test

[Yunsheng Lin <linyunsheng@huawei.com>]

On 2024/1/5 0:17, Eugenio Perez Martin wrote:
> On Wed, Jan 3, 2024 at 11:00 AM Yunsheng Lin <linyunsheng@huawei.com> wrote:

...

>> +
>> +static void run_tx_test(struct vdev_info *dev, struct vq_info *vq,
>> +                       bool delayed, int batch, int bufs)
>> +{
>> +       const bool random_batch = batch == RANDOM_BATCH;
>> +       long long spurious = 0;
>> +       struct scatterlist sl;
>> +       unsigned int len;
>> +       int r;
>> +
>> +       for (;;) {
>> +               long started_before = vq->started;
>> +               long completed_before = vq->completed;
>> +
>> +               virtqueue_disable_cb(vq->vq);
>> +               do {
>> +                       if (random_batch)
>> +                               batch = (random() % vq->vring.num) + 1;
>> +
>> +                       while (vq->started < bufs &&
>> +                              (vq->started - vq->completed) < batch) {
>> +                               sg_init_one(&sl, dev->test_buf, HDR_LEN + TEST_BUF_LEN);
>> +                               r = virtqueue_add_outbuf(vq->vq, &sl, 1,
>> +                                                        dev->test_buf + vq->started,
>> +                                                        GFP_ATOMIC);
>> +                               if (unlikely(r != 0)) {
>> +                                       if (r == -ENOSPC &&
>> +                                           vq->started > started_before)
>> +                                               r = 0;
>> +                                       else
>> +                                               r = -1;
>> +                                       break;
>> +                               }
>> +
>> +                               ++vq->started;
>> +
>> +                               if (unlikely(!virtqueue_kick(vq->vq))) {
>> +                                       r = -1;
>> +                                       break;
>> +                               }
>> +                       }
>> +
>> +                       if (vq->started >= bufs)
>> +                               r = -1;
>> +
>> +                       /* Flush out completed bufs if any */
>> +                       while (virtqueue_get_buf(vq->vq, &len)) {
>> +                               int n, i;
>> +
>> +                               n = recvfrom(dev->sock, dev->res_buf, TEST_BUF_LEN, 0, NULL, NULL);
>> +                               assert(n == TEST_BUF_LEN);
>> +
>> +                               for (i = ETHER_HDR_LEN; i < n; i++)
>> +                                       assert(dev->res_buf[i] == (char)i);
>> +
>> +                               ++vq->completed;
>> +                               r = 0;
>> +                       }
>> +               } while (r == 0);
>> +
>> +               if (vq->completed == completed_before && vq->started == started_before)
>> +                       ++spurious;
>> +
>> +               assert(vq->completed <= bufs);
>> +               assert(vq->started <= bufs);
>> +               if (vq->completed == bufs)
>> +                       break;
>> +
>> +               if (delayed) {
>> +                       if (virtqueue_enable_cb_delayed(vq->vq))
>> +                               wait_for_interrupt(vq);
>> +               } else {
>> +                       if (virtqueue_enable_cb(vq->vq))
>> +                               wait_for_interrupt(vq);
>> +               }
>> +       }
>> +       printf("TX spurious wakeups: 0x%llx started=0x%lx completed=0x%lx\n",
>> +              spurious, vq->started, vq->completed);
>> +}
>> +
>> +static void run_rx_test(struct vdev_info *dev, struct vq_info *vq,
>> +                       bool delayed, int batch, int bufs)
>> +{
>> +       const bool random_batch = batch == RANDOM_BATCH;
>> +       long long spurious = 0;
>> +       struct scatterlist sl;
>> +       unsigned int len;
>> +       int r;
>> +
>> +       for (;;) {
>> +               long started_before = vq->started;
>> +               long completed_before = vq->completed;
>> +
>> +               do {
>> +                       if (random_batch)
>> +                               batch = (random() % vq->vring.num) + 1;
>> +
>> +                       while (vq->started < bufs &&
>> +                              (vq->started - vq->completed) < batch) {
>> +                               sg_init_one(&sl, dev->res_buf, HDR_LEN + TEST_BUF_LEN);
>> +
>> +                               r = virtqueue_add_inbuf(vq->vq, &sl, 1,
>> +                                                       dev->res_buf + vq->started,
>> +                                                       GFP_ATOMIC);
>> +                               if (unlikely(r != 0)) {
>> +                                       if (r == -ENOSPC &&
>> +                                           vq->started > started_before)
>> +                                               r = 0;
>> +                                       else
>> +                                               r = -1;
>> +                                       break;
>> +                               }
>> +
>> +                               ++vq->started;
>> +
>> +                               vdev_send_packet(dev);
>> +
>> +                               if (unlikely(!virtqueue_kick(vq->vq))) {
>> +                                       r = -1;
>> +                                       break;
>> +                               }
>> +                       }
>> +
>> +                       if (vq->started >= bufs)
>> +                               r = -1;
>> +
>> +                       /* Flush out completed bufs if any */
>> +                       while (virtqueue_get_buf(vq->vq, &len)) {
>> +                               struct ether_header *eh;
>> +                               int i;
>> +
>> +                               eh = (struct ether_header *)(dev->res_buf + HDR_LEN);
>> +
>> +                               /* tun netdev is up and running, ignore the
>> +                                * non-TEST_PTYPE packet.
>> +                                */
>> +                               if (eh->ether_type != htons(TEST_PTYPE)) {
>> +                                       ++vq->completed;
>> +                                       r = 0;
>> +                                       continue;
>> +                               }
>> +
>> +                               assert(len == TEST_BUF_LEN + HDR_LEN);
>> +
>> +                               for (i = ETHER_HDR_LEN; i < TEST_BUF_LEN; i++)
>> +                                       assert(dev->res_buf[i + HDR_LEN] == (char)i);
>> +
>> +                               ++vq->completed;
>> +                               r = 0;
>> +                       }
>> +               } while (r == 0);
>> +               if (vq->completed == completed_before && vq->started == started_before)
>> +                       ++spurious;
>> +
>> +               assert(vq->completed <= bufs);
>> +               assert(vq->started <= bufs);
>> +               if (vq->completed == bufs)
>> +                       break;
>> +       }
>> +
>> +       printf("RX spurious wakeups: 0x%llx started=0x%lx completed=0x%lx\n",
>> +              spurious, vq->started, vq->completed);
>> +}
> 
> Hi!
> 
> I think the tests are great! Maybe both run_rx_test and run_tx_test
> (and virtio_test.c:run_test) can be merged into a common function with
> some callbacks? Not sure if it will complicate the code more.

I looked at it more closely, it seems using callback just make the code
more complicated without obvious benefit, as the main steps is different
for tx and rx.

For tx:
1. Prepare a out buf
2. Kick the vhost_net to do tx processing
3. Do the receiving in the tun side
4. verify the data received by tun is correct

For rx:
1. Prepare a in buf
2. Do the sending in the tun side
3. Kick the vhost_net to do rx processing
4. verify the data received by vhost_net is correct

I could refactor out a common function to do the data verifying for step 4
of both tx and rx.

For virtio_test.c:run_test, it does not seems to be using the vhost_net directly,
it uses shim vhost_test.ko module, and it seems to only have step 1 & 3 of
vhost_net_test' rx testing. The new vhost_net_test should be able to replace the
virtio_test, I thought about deleting the virtio_test after adding the vhost_net_test,
but I am not familiar enough with virtio to do the judgement yet.

> 
> Thanks!
>