On Tue, Mar 19, 2019 at 05:37:34PM +0800, Tiwei Bie wrote:
On Tue, Mar 19, 2019 at 09:54:03AM +0100, Jens Freimann wrote:
On Tue, Mar 19, 2019 at 02:43:06PM +0800, Tiwei Bie wrote:
> Cache the AVAIL, USED and WRITE bits to avoid calculating
> them as much as possible. Note that, the WRITE bit isn't
> cached for control queue.
>
> Signed-off-by: Tiwei Bie <tiwei....@intel.com>
> ---
> drivers/net/virtio/virtio_ethdev.c | 35 ++++++++++++++----------------
> drivers/net/virtio/virtio_rxtx.c | 31 ++++++++++----------------
> drivers/net/virtio/virtqueue.h | 8 +++----
> 3 files changed, 32 insertions(+), 42 deletions(-)
>
> diff --git a/drivers/net/virtio/virtio_ethdev.c
b/drivers/net/virtio/virtio_ethdev.c
> index ff16fb63e..9060b6b33 100644
> --- a/drivers/net/virtio/virtio_ethdev.c
> +++ b/drivers/net/virtio/virtio_ethdev.c
> @@ -149,7 +149,7 @@ virtio_send_command_packed(struct virtnet_ctl *cvq,
> int head;
> struct vring_packed_desc *desc = vq->ring_packed.desc_packed;
> struct virtio_pmd_ctrl *result;
> - bool avail_wrap_counter;
> + uint16_t flags;
> int sum = 0;
> int nb_descs = 0;
> int k;
> @@ -161,14 +161,15 @@ virtio_send_command_packed(struct virtnet_ctl *cvq,
> * One RX packet for ACK.
> */
> head = vq->vq_avail_idx;
> - avail_wrap_counter = vq->avail_wrap_counter;
> + flags = vq->cached_flags;
> desc[head].addr = cvq->virtio_net_hdr_mem;
> desc[head].len = sizeof(struct virtio_net_ctrl_hdr);
> vq->vq_free_cnt--;
> nb_descs++;
> if (++vq->vq_avail_idx >= vq->vq_nentries) {
> vq->vq_avail_idx -= vq->vq_nentries;
> - vq->avail_wrap_counter ^= 1;
> + vq->cached_flags ^=
> + VRING_DESC_F_AVAIL(1) | VRING_DESC_F_USED(1);
Maybe name it avail_used_flags instead of cached flags. Also we could
use a constant value.
It also contains the WRITE bit (not just AVAIL and USED bits)
for Rx path. That's why I didn't name it as avail_used_flags.
ok
> }
>
> for (k = 0; k < pkt_num; k++) {
> @@ -177,34 +178,31 @@ virtio_send_command_packed(struct virtnet_ctl *cvq,
> + sizeof(ctrl->status) + sizeof(uint8_t) * sum;
> desc[vq->vq_avail_idx].len = dlen[k];
> desc[vq->vq_avail_idx].flags = VRING_DESC_F_NEXT |
> - VRING_DESC_F_AVAIL(vq->avail_wrap_counter) |
> - VRING_DESC_F_USED(!vq->avail_wrap_counter);
> + vq->cached_flags;
> sum += dlen[k];
> vq->vq_free_cnt--;
> nb_descs++;
> if (++vq->vq_avail_idx >= vq->vq_nentries) {
> vq->vq_avail_idx -= vq->vq_nentries;
> - vq->avail_wrap_counter ^= 1;
> + vq->cached_flags ^=
> + VRING_DESC_F_AVAIL(1) | VRING_DESC_F_USED(1);
> }
> }
>
> desc[vq->vq_avail_idx].addr = cvq->virtio_net_hdr_mem
> + sizeof(struct virtio_net_ctrl_hdr);
> desc[vq->vq_avail_idx].len = sizeof(ctrl->status);
> - desc[vq->vq_avail_idx].flags = VRING_DESC_F_WRITE |
> - VRING_DESC_F_AVAIL(vq->avail_wrap_counter) |
> - VRING_DESC_F_USED(!vq->avail_wrap_counter);
> + desc[vq->vq_avail_idx].flags = VRING_DESC_F_WRITE | vq->cached_flags;
> vq->vq_free_cnt--;
> nb_descs++;
> if (++vq->vq_avail_idx >= vq->vq_nentries) {
> vq->vq_avail_idx -= vq->vq_nentries;
> - vq->avail_wrap_counter ^= 1;
> + vq->cached_flags ^=
> + VRING_DESC_F_AVAIL(1) | VRING_DESC_F_USED(1);
> }
>
> virtio_wmb(vq->hw->weak_barriers);
> - desc[head].flags = VRING_DESC_F_NEXT |
> - VRING_DESC_F_AVAIL(avail_wrap_counter) |
> - VRING_DESC_F_USED(!avail_wrap_counter);
> + desc[head].flags = VRING_DESC_F_NEXT | flags;
>
> virtio_wmb(vq->hw->weak_barriers);
> virtqueue_notify(vq);
> @@ -226,12 +224,12 @@ virtio_send_command_packed(struct virtnet_ctl *cvq,
> PMD_INIT_LOG(DEBUG, "vq->vq_free_cnt=%d\n"
> "vq->vq_avail_idx=%d\n"
> "vq->vq_used_cons_idx=%d\n"
> - "vq->avail_wrap_counter=%d\n"
> + "vq->cached_flags=0x%x\n"
> "vq->used_wrap_counter=%d\n",
> vq->vq_free_cnt,
> vq->vq_avail_idx,
> vq->vq_used_cons_idx,
> - vq->avail_wrap_counter,
> + vq->cached_flags,
> vq->used_wrap_counter);
>
> result = cvq->virtio_net_hdr_mz->addr;
> @@ -491,11 +489,10 @@ virtio_init_queue(struct rte_eth_dev *dev, uint16_t
vtpci_queue_idx)
> vq->vq_nentries = vq_size;
> vq->event_flags_shadow = 0;
> if (vtpci_packed_queue(hw)) {
> - vq->avail_wrap_counter = 1;
> vq->used_wrap_counter = 1;
> - vq->avail_used_flags =
> - VRING_DESC_F_AVAIL(vq->avail_wrap_counter) |
> - VRING_DESC_F_USED(!vq->avail_wrap_counter);
> + vq->cached_flags = VRING_DESC_F_AVAIL(1);
> + if (queue_type == VTNET_RQ)
> + vq->cached_flags |= VRING_DESC_F_WRITE;
> }
>
> /*
> diff --git a/drivers/net/virtio/virtio_rxtx.c
b/drivers/net/virtio/virtio_rxtx.c
> index 771d3c3f6..3c354baef 100644
> --- a/drivers/net/virtio/virtio_rxtx.c
> +++ b/drivers/net/virtio/virtio_rxtx.c
> @@ -431,7 +431,7 @@ virtqueue_enqueue_recv_refill_packed(struct virtqueue *vq,
> struct rte_mbuf **cookie, uint16_t num)
> {
> struct vring_packed_desc *start_dp = vq->ring_packed.desc_packed;
> - uint16_t flags = VRING_DESC_F_WRITE | vq->avail_used_flags;
> + uint16_t flags = vq->cached_flags;
> struct virtio_hw *hw = vq->hw;
> struct vq_desc_extra *dxp;
> uint16_t idx;
> @@ -460,11 +460,9 @@ virtqueue_enqueue_recv_refill_packed(struct virtqueue
*vq,
> start_dp[idx].flags = flags;
> if (++vq->vq_avail_idx >= vq->vq_nentries) {
> vq->vq_avail_idx -= vq->vq_nentries;
> - vq->avail_wrap_counter ^= 1;
> - vq->avail_used_flags =
> - VRING_DESC_F_AVAIL(vq->avail_wrap_counter) |
> - VRING_DESC_F_USED(!vq->avail_wrap_counter);
> - flags = VRING_DESC_F_WRITE | vq->avail_used_flags;
> + vq->cached_flags ^=
> + VRING_DESC_F_AVAIL(1) | VRING_DESC_F_USED(1);
> + flags = vq->cached_flags;
same here. it's not really cached, it's pre-calculated. And here we
could also use a pre-calculated constand/define.
For pre-calculated constant/define, do you mean VRING_DESC_F_AVAIL(1)
and VRING_DESC_F_USED(1)? There is still little code in virtio-user
using them without constantly passing 1. I planned to fully get rid
of them in a separate patch later (but I can do it in this series if
anyone wants).
Yes, that's what I meant. And it's fine by me if you do it in a
follow-up.
Otherwise looks good! Did you see any performance improvements?
Yeah, I saw slightly better performance in a quick test.
Nice.
Reviewed-by: Jens Freimann <jfreim...@redhat.com>
regards,
Jens
regards,
Jens
