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[54.67.115.33]) by smtp.gmail.com with ESMTPSA id p12-20020a1709028a8c00b001a198422025sm1990339plo.125.2023.03.17.14.52.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 17 Mar 2023 14:52:57 -0700 (PDT) Date: Fri, 17 Mar 2023 21:52:56 +0000 From: Bobby Eshleman To: Arseniy Krasnov Cc: Stefan Hajnoczi , Stefano Garzarella , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Bobby Eshleman , kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@sberdevices.ru, oxffffaa@gmail.com Subject: Re: [RFC PATCH v1] virtio/vsock: allocate multiple skbuffs on tx Message-ID: References: <2c52aa26-8181-d37a-bccd-a86bd3cbc6e1@sberdevices.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2c52aa26-8181-d37a-bccd-a86bd3cbc6e1@sberdevices.ru> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, Mar 17, 2023 at 01:38:39PM +0300, Arseniy Krasnov wrote: > This adds small optimization for tx path: instead of allocating single > skbuff on every call to transport, allocate multiple skbuffs until > credit space allows, thus trying to send as much as possible data without > return to af_vsock.c. Hey Arseniy, I really like this optimization. I have a few questions/comments below. > > Signed-off-by: Arseniy Krasnov > --- > net/vmw_vsock/virtio_transport_common.c | 45 +++++++++++++++++-------- > 1 file changed, 31 insertions(+), 14 deletions(-) > > diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c > index 6564192e7f20..cda587196475 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 +224,37 @@ 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; > - } > + rest_len = pkt_len; > > - virtio_transport_inc_tx_pkt(vvs, skb); > + 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; > + goto out; > + } In this case, if a previous round of the loop succeeded with send_pkt(), I think that we may still want to return the number of bytes that have successfully been sent so far? > > - return t_ops->send_pkt(skb); > + virtio_transport_inc_tx_pkt(vvs, skb); > + > + ret = t_ops->send_pkt(skb); > + > + if (ret < 0) > + goto out; Ditto here. > + > + rest_len -= skb_len; > + } while (rest_len); > + > + return pkt_len; > + > +out: > + virtio_transport_put_credit(vvs, rest_len); > + return ret; > } > > static bool virtio_transport_inc_rx_pkt(struct virtio_vsock_sock *vvs, > -- > 2.25.1