On 20.03.2023 17:29, Stefano Garzarella wrote: > On Sun, Mar 19, 2023 at 09:46:10PM +0300, Arseniy Krasnov wrote: >> This adds small optimization for tx path: instead of allocating single >> skbuff on every call to transport, allocate multiple skbuff's until >> credit space allows, thus trying to send as much as possible data without >> return to af_vsock.c. >> >> Signed-off-by: Arseniy Krasnov <AVKrasnov@xxxxxxxxxxxxxx> >> --- >> Link to v1: >> https://lore.kernel.org/netdev/2c52aa26-8181-d37a-bccd-a86bd3cbc6e1@xxxxxxxxxxxxxx/ >> >> Changelog: >> v1 -> v2: >> - If sent something, return number of bytes sent (even in >> case of error). Return error only if failed to sent first >> skbuff. >> >> net/vmw_vsock/virtio_transport_common.c | 53 ++++++++++++++++++------- >> 1 file changed, 39 insertions(+), 14 deletions(-) >> >> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c >> index 6564192e7f20..3fdf1433ec28 100644 >> --- a/net/vmw_vsock/virtio_transport_common.c >> +++ b/net/vmw_vsock/virtio_transport_common.c >> @@ -196,7 +196,8 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk, >> const struct virtio_transport *t_ops; >> struct virtio_vsock_sock *vvs; >> u32 pkt_len = info->pkt_len; >> - struct sk_buff *skb; >> + u32 rest_len; >> + int ret; >> >> info->type = virtio_transport_get_type(sk_vsock(vsk)); >> >> @@ -216,10 +217,6 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk, >> >> vvs = vsk->trans; >> >> - /* we can send less than pkt_len bytes */ >> - if (pkt_len > VIRTIO_VSOCK_MAX_PKT_BUF_SIZE) >> - pkt_len = VIRTIO_VSOCK_MAX_PKT_BUF_SIZE; >> - >> /* virtio_transport_get_credit might return less than pkt_len credit */ >> pkt_len = virtio_transport_get_credit(vvs, pkt_len); >> >> @@ -227,17 +224,45 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk, >> if (pkt_len == 0 && info->op == VIRTIO_VSOCK_OP_RW) >> return pkt_len; >> >> - skb = virtio_transport_alloc_skb(info, pkt_len, >> - src_cid, src_port, >> - dst_cid, dst_port); >> - if (!skb) { >> - virtio_transport_put_credit(vvs, pkt_len); >> - return -ENOMEM; >> - } >> + ret = 0; >> + rest_len = pkt_len; >> + >> + do { >> + struct sk_buff *skb; >> + size_t skb_len; >> + >> + skb_len = min_t(u32, VIRTIO_VSOCK_MAX_PKT_BUF_SIZE, rest_len); >> + >> + skb = virtio_transport_alloc_skb(info, skb_len, >> + src_cid, src_port, >> + dst_cid, dst_port); >> + if (!skb) { >> + ret = -ENOMEM; >> + break; >> + } >> + >> + virtio_transport_inc_tx_pkt(vvs, skb); >> + >> + ret = t_ops->send_pkt(skb); >> + >> + if (ret < 0) >> + break; >> >> - virtio_transport_inc_tx_pkt(vvs, skb); >> + rest_len -= skb_len; > > t_ops->send_pkt() is returning the number of bytes sent. Current > implementations always return `skb_len`, so there should be no problem, > but it would be better to put a comment here, or we should handle the > case where ret != skb_len to avoid future issues. Hello, thanks for review! I see. I think i'll handle such partial sends (ret != skb_len) as error, as it is the only thing to do - we remove 'skb_len' from user's buffer, but 'send_pkt()' returns another value, so it will be strange for me to continue this tx loop as everything is ok. Something like this: + + if (ret < 0) + break; + + if (ret != skb_len) { + ret = -EFAULT;//or may be -EIO + break; + } > >> + } while (rest_len); >> >> - return t_ops->send_pkt(skb); >> + /* Don't call this function with zero as argument: >> + * it tries to acquire spinlock and such argument >> + * makes this call useless. > > Good point, can we do the same also for virtio_transport_get_credit()? > (Maybe in a separate patch) > > I'm thinking if may be better to do it directly inside the functions, > but I don't have a strong opinion on that since we only call them here. > I think in this patch i can call 'virtio_transport_put_credit()' without if, but i'll prepare separate patch which adds zero argument check to this function. As i see, the only function suitable for such 'if' condition is 'virtio_transport_put_credit()'. Anyway - for future use this check won't be bad. Thanks, Arseniy > Thanks, > Stefano > >> + */ >> + if (rest_len) >> + virtio_transport_put_credit(vvs, rest_len); >> + >> + /* Return number of bytes, if any data has been sent. */ >> + if (rest_len != pkt_len) >> + ret = pkt_len - rest_len; >> + >> + return ret; >> } >> >> static bool virtio_transport_inc_rx_pkt(struct virtio_vsock_sock *vvs, >> -- >> 2.25.1 >> >
