On Thu, 17 Jun 2021 11:08:34 +0800, Jason Wang <jasow...@redhat.com> wrote:
>
> 在 2021/6/10 下午4:22, Xuan Zhuo 写道:
> > After testing, the performance of calling kick every time is not stable.
> > And if all the packets are sent and kicked again, the performance is not
> > good. So add a module parameter to specify how many packets are sent to
> > call a kick.
> >
> > 8 is a relatively stable value with the best performance.
> >
> > Here is the pps of the test of xsk_kick_thr under different values (from
> > 1 to 64).
> >
> > thr PPS thr PPS thr PPS
> > 1 2924116.74247 | 23 3683263.04348 | 45 2777907.22963
> > 2 3441010.57191 | 24 3078880.13043 | 46 2781376.21739
> > 3 3636728.72378 | 25 2859219.57656 | 47 2777271.91304
> > 4 3637518.61468 | 26 2851557.9593 | 48 2800320.56575
> > 5 3651738.16251 | 27 2834783.54408 | 49 2813039.87599
> > 6 3652176.69231 | 28 2847012.41472 | 50 3445143.01839
> > 7 3665415.80602 | 29 2860633.91304 | 51 3666918.01281
> > 8 3665045.16555 | 30 2857903.5786 | 52 3059929.2709
>
>
> I wonder what's the number for the case of non zc xsk?
These data are used to compare the situation of sending different numbers of
packets to virtio at one time. I think it has nothing to do with non-zerocopy
xsk.
Thanks.
>
> Thanks
>
>
> > 9 3671023.2401 | 31 2835589.98963 | 53 2831515.21739
> > 10 3669532.23274 | 32 2862827.88706 | 54 3451804.07204
> > 11 3666160.37749 | 33 2871855.96696 | 55 3654975.92385
> > 12 3674951.44813 | 34 3434456.44816 | 56 3676198.3188
> > 13 3667447.57331 | 35 3656918.54177 | 57 3684740.85619
> > 14 3018846.0503 | 36 3596921.16722 | 58 3060958.8594
> > 15 2792773.84505 | 37 3603460.63903 | 59 2828874.57191
> > 16 3430596.3602 | 38 3595410.87666 | 60 3459926.11027
> > 17 3660525.85806 | 39 3604250.17819 | 61 3685444.47599
> > 18 3045627.69054 | 40 3596542.28428 | 62 3049959.0809
> > 19 2841542.94177 | 41 3600705.16054 | 63 2806280.04013
> > 20 2830475.97348 | 42 3019833.71191 | 64 3448494.3913
> > 21 2845655.55789 | 43 2752951.93264 |
> > 22 3450389.84365 | 44 2753107.27164 |
> >
> > It can be found that when the value of xsk_kick_thr is relatively small,
> > the performance is not good, and when its value is greater than 13, the
> > performance will be more irregular and unstable. It looks similar from 3
> > to 13, I chose 8 as the default value.
> >
> > The test environment is qemu + vhost-net. I modified vhost-net to drop
> > the packets sent by vm directly, so that the cpu of vm can run higher.
> > By default, the processes in the vm and the cpu of softirqd are too low,
> > and there is no obvious difference in the test data.
> >
> > During the test, the cpu of softirq reached 100%. Each xsk_kick_thr was
> > run for 300s, the pps of every second was recorded, and the average of
> > the pps was finally taken. The vhost process cpu on the host has also
> > reached 100%.
> >
> > Signed-off-by: Xuan Zhuo <xuanz...@linux.alibaba.com>
> > Reviewed-by: Dust Li <dust...@linux.alibaba.com>
> > ---
> > drivers/net/virtio/virtio_net.c | 1 +
> > drivers/net/virtio/xsk.c | 18 ++++++++++++++++--
> > drivers/net/virtio/xsk.h | 2 ++
> > 3 files changed, 19 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/virtio/virtio_net.c
> > b/drivers/net/virtio/virtio_net.c
> > index 9503133e71f0..dfe509939b45 100644
> > --- a/drivers/net/virtio/virtio_net.c
> > +++ b/drivers/net/virtio/virtio_net.c
> > @@ -14,6 +14,7 @@ static bool csum = true, gso = true, napi_tx = true;
> > module_param(csum, bool, 0444);
> > module_param(gso, bool, 0444);
> > module_param(napi_tx, bool, 0644);
> > +module_param(xsk_kick_thr, int, 0644);
> >
> > /* FIXME: MTU in config. */
> > #define GOOD_PACKET_LEN (ETH_HLEN + VLAN_HLEN + ETH_DATA_LEN)
> > diff --git a/drivers/net/virtio/xsk.c b/drivers/net/virtio/xsk.c
> > index 3973c82d1ad2..2f3ba6ab4798 100644
> > --- a/drivers/net/virtio/xsk.c
> > +++ b/drivers/net/virtio/xsk.c
> > @@ -5,6 +5,8 @@
> >
> > #include "virtio_net.h"
> >
> > +int xsk_kick_thr = 8;
> > +
> > static struct virtio_net_hdr_mrg_rxbuf xsk_hdr;
> >
> > static struct virtnet_xsk_ctx *virtnet_xsk_ctx_get(struct
> > virtnet_xsk_ctx_head *head)
> > @@ -455,6 +457,7 @@ static int virtnet_xsk_xmit_batch(struct send_queue *sq,
> > struct xdp_desc desc;
> > int err, packet = 0;
> > int ret = -EAGAIN;
> > + int need_kick = 0;
> >
> > while (budget-- > 0) {
> > if (sq->vq->num_free < 2 + MAX_SKB_FRAGS) {
> > @@ -475,11 +478,22 @@ static int virtnet_xsk_xmit_batch(struct send_queue
> > *sq,
> > }
> >
> > ++packet;
> > + ++need_kick;
> > + if (need_kick > xsk_kick_thr) {
> > + if (virtqueue_kick_prepare(sq->vq) &&
> > + virtqueue_notify(sq->vq))
> > + ++stats->kicks;
> > +
> > + need_kick = 0;
> > + }
> > }
> >
> > if (packet) {
> > - if (virtqueue_kick_prepare(sq->vq) && virtqueue_notify(sq->vq))
> > - ++stats->kicks;
> > + if (need_kick) {
> > + if (virtqueue_kick_prepare(sq->vq) &&
> > + virtqueue_notify(sq->vq))
> > + ++stats->kicks;
> > + }
> >
> > *done += packet;
> > stats->xdp_tx += packet;
> > diff --git a/drivers/net/virtio/xsk.h b/drivers/net/virtio/xsk.h
> > index fe22cf78d505..4f0f4f9cf23b 100644
> > --- a/drivers/net/virtio/xsk.h
> > +++ b/drivers/net/virtio/xsk.h
> > @@ -7,6 +7,8 @@
> >
> > #define VIRTNET_XSK_BUFF_CTX ((void *)(unsigned long)~0L)
> >
> > +extern int xsk_kick_thr;
> > +
> > /* When xsk disable, under normal circumstances, the network card must
> > reclaim
> > * all the memory that has been sent and the memory added to the rq queue
> > by
> > * destroying the queue.
>
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