From: Stefano Garzarella <sgarzare@redhat.com>
To: Arseniy Krasnov <avkrasnov@sberdevices.ru>
Cc: Stefan Hajnoczi <stefanha@redhat.com>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>,
Paolo Abeni <pabeni@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
Jason Wang <jasowang@redhat.com>,
Bobby Eshleman <bobby.eshleman@bytedance.com>,
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 v4 03/17] vsock/virtio: support to send non-linear skb
Date: Tue, 27 Jun 2023 09:49:01 +0200 [thread overview]
Message-ID: <6g6rfqbfkmfn5or56v25xny6lyhixj6plmrnyg77hirz7dzzhn@jskeqmnbthhk> (raw)
In-Reply-To: <0a89e51b-0f7f-b64b-c827-7c943d6f08a6@sberdevices.ru>
On Tue, Jun 27, 2023 at 07:39:41AM +0300, Arseniy Krasnov wrote:
>
>
>On 26.06.2023 18:36, Stefano Garzarella wrote:
>> On Sat, Jun 03, 2023 at 11:49:25PM +0300, Arseniy Krasnov wrote:
>>> For non-linear skb use its pages from fragment array as buffers in
>>> virtio tx queue. These pages are already pinned by 'get_user_pages()'
>>> during such skb creation.
>>>
>>> Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
>>> ---
>>> net/vmw_vsock/virtio_transport.c | 37 ++++++++++++++++++++++++++------
>>> 1 file changed, 31 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
>>> index e95df847176b..6053d8341091 100644
>>> --- a/net/vmw_vsock/virtio_transport.c
>>> +++ b/net/vmw_vsock/virtio_transport.c
>>> @@ -100,7 +100,9 @@ virtio_transport_send_pkt_work(struct work_struct *work)
>>> vq = vsock->vqs[VSOCK_VQ_TX];
>>>
>>> for (;;) {
>>> - struct scatterlist hdr, buf, *sgs[2];
>>> + /* +1 is for packet header. */
>>> + struct scatterlist *sgs[MAX_SKB_FRAGS + 1];
>>> + struct scatterlist bufs[MAX_SKB_FRAGS + 1];
>>> int ret, in_sg = 0, out_sg = 0;
>>> struct sk_buff *skb;
>>> bool reply;
>>> @@ -111,12 +113,35 @@ virtio_transport_send_pkt_work(struct work_struct *work)
>>>
>>> virtio_transport_deliver_tap_pkt(skb);
>>> reply = virtio_vsock_skb_reply(skb);
>>> + sg_init_one(&bufs[0], virtio_vsock_hdr(skb), sizeof(*virtio_vsock_hdr(skb)));
>>> + sgs[out_sg++] = &bufs[0];
>>
>> Can we use out_sg also to index bufs (here and in the rest of the code)?
>>
>> E.g.
>>
>> sg_init_one(&bufs[out_sg], ...)
>> sgs[out_sg] = &bufs[out_sg];
>> ++out_sg;
>>
>> ...
>> if (skb->len > 0) {
>> sg_init_one(&bufs[out_sg], skb->data, skb->len);
>> sgs[out_sg] = &bufs[out_sg];
>> ++out_sg;
>> }
>>
>> etc...
>>
>>> +
>>
>> For readability, I would move the smaller branch above:
>>
>> if (!skb_is_nonlinear(skb)) {
>> // small block
>> ...
>> } else {
>> // big block
>> ...
>> }
>>
>>> + if (skb_is_nonlinear(skb)) {
>>> + struct skb_shared_info *si;
>>> + int i;
>>> +
>>> + si = skb_shinfo(skb);
>>> +
>>> + for (i = 0; i < si->nr_frags; i++) {
>>> + skb_frag_t *skb_frag = &si->frags[i];
>>> + void *va = page_to_virt(skb_frag->bv_page);
>>> +
>>> + /* We will use 'page_to_virt()' for userspace page here,
>>> + * because virtio layer will call 'virt_to_phys()' later
>>> + * to fill buffer descriptor. We don't touch memory at
>>> + * "virtual" address of this page.
>>> + */
>>> + sg_init_one(&bufs[i + 1],
>>> + va + skb_frag->bv_offset,
>>> + skb_frag->bv_len);
>>> + sgs[out_sg++] = &bufs[i + 1];
>>> + }
>>> + } else {
>>> + if (skb->len > 0) {
>>
>> Should we do the same check (skb->len > 0) for nonlinear skb as well?
>> Or do the nonlinear ones necessarily have len > 0?
>
>Yes, non-linear skb always has 'data_len' > 0, e.g. such skbs always have some
>data in it.
Okay, makes sense ;-)
Thanks,
Stefano
>
>Thanks, Arseniy
>
>>
>>> + sg_init_one(&bufs[1], skb->data, skb->len);
>>> + sgs[out_sg++] = &bufs[1];
>>> + }
>>>
>> ^
>> Blank line that we can remove.
>>
>> Stefano
>>
>>> - sg_init_one(&hdr, virtio_vsock_hdr(skb), sizeof(*virtio_vsock_hdr(skb)));
>>> - sgs[out_sg++] = &hdr;
>>> - if (skb->len > 0) {
>>> - sg_init_one(&buf, skb->data, skb->len);
>>> - sgs[out_sg++] = &buf;
>>> }
>>>
>>> ret = virtqueue_add_sgs(vq, sgs, out_sg, in_sg, skb, GFP_KERNEL);
>>> --
>>> 2.25.1
>>>
>>
>
next prev parent reply other threads:[~2023-06-27 7:49 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-03 20:49 [RFC PATCH v4 00/17] vsock: MSG_ZEROCOPY flag support Arseniy Krasnov
2023-06-03 20:49 ` [RFC PATCH v4 01/17] vsock/virtio: read data from non-linear skb Arseniy Krasnov
2023-06-12 17:43 ` Bobby Eshleman
2023-06-26 15:20 ` Stefano Garzarella
2023-06-03 20:49 ` [RFC PATCH v4 02/17] vhost/vsock: " Arseniy Krasnov
2023-06-12 17:53 ` Bobby Eshleman
2023-06-26 15:24 ` Stefano Garzarella
2023-06-03 20:49 ` [RFC PATCH v4 03/17] vsock/virtio: support to send " Arseniy Krasnov
2023-06-12 18:30 ` Bobby Eshleman
2023-06-26 15:36 ` Stefano Garzarella
2023-06-27 4:39 ` Arseniy Krasnov
2023-06-27 7:49 ` Stefano Garzarella [this message]
2023-06-03 20:49 ` [RFC PATCH v4 04/17] vsock/virtio: non-linear skb handling for tap Arseniy Krasnov
2023-06-26 15:43 ` Stefano Garzarella
2023-06-03 20:49 ` [RFC PATCH v4 05/17] vsock/virtio: MSG_ZEROCOPY flag support Arseniy Krasnov
2023-06-26 16:03 ` Stefano Garzarella
2023-06-27 4:41 ` Arseniy Krasnov
2023-06-27 7:50 ` Stefano Garzarella
2023-06-27 8:22 ` Arseniy Krasnov
2023-06-29 12:32 ` Stefano Garzarella
2023-06-03 20:49 ` [RFC PATCH v4 06/17] vsock: check error queue to set EPOLLERR Arseniy Krasnov
2023-06-26 16:04 ` Stefano Garzarella
2023-06-27 4:44 ` Arseniy Krasnov
2023-06-27 7:53 ` Stefano Garzarella
2023-06-03 20:49 ` [RFC PATCH v4 07/17] vsock: read from socket's error queue Arseniy Krasnov
2023-06-26 16:08 ` Stefano Garzarella
2023-06-27 4:49 ` Arseniy Krasnov
2023-06-27 7:58 ` Stefano Garzarella
2023-06-03 20:49 ` [RFC PATCH v4 08/17] vsock: check for MSG_ZEROCOPY support on send Arseniy Krasnov
2023-06-03 20:49 ` [RFC PATCH v4 09/17] vsock: enable SOCK_SUPPORT_ZC bit Arseniy Krasnov
2023-06-03 20:49 ` [RFC PATCH v4 10/17] vhost/vsock: support MSG_ZEROCOPY for transport Arseniy Krasnov
2023-06-26 16:10 ` Stefano Garzarella
2023-06-03 20:49 ` [RFC PATCH v4 11/17] vsock/virtio: " Arseniy Krasnov
2023-06-26 16:11 ` Stefano Garzarella
2023-06-03 20:49 ` [RFC PATCH v4 12/17] vsock/loopback: " Arseniy Krasnov
2023-06-26 16:14 ` Stefano Garzarella
2023-06-03 20:49 ` [RFC PATCH v4 13/17] net/sock: enable setting SO_ZEROCOPY for PF_VSOCK Arseniy Krasnov
2023-06-03 20:49 ` [RFC PATCH v4 14/17] docs: net: description of MSG_ZEROCOPY for AF_VSOCK Arseniy Krasnov
2023-06-03 20:49 ` [RFC PATCH v4 15/17] test/vsock: MSG_ZEROCOPY flag tests Arseniy Krasnov
2023-06-03 20:49 ` [RFC PATCH v4 16/17] test/vsock: MSG_ZEROCOPY support for vsock_perf Arseniy Krasnov
2023-06-03 20:49 ` [RFC PATCH v4 17/17] test/vsock: io_uring rx/tx tests Arseniy Krasnov
2023-06-12 17:20 ` [RFC PATCH v4 00/17] vsock: MSG_ZEROCOPY flag support Bobby Eshleman
2023-06-14 5:39 ` Arseniy Krasnov
2023-06-26 16:15 ` Stefano Garzarella
2023-06-27 4:55 ` Arseniy Krasnov
2023-06-27 8:01 ` Stefano Garzarella
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