From: "Xie, Huawei" <huawei.xie@intel.com>
To: "Ouyang, Changchun" <changchun.ouyang@intel.com>,
"dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [PATCH v2 1/5] lib_vhost: Fix enqueue/dequeue can't handle chained vring descriptors
Date: Sun, 31 May 2015 05:03:47 +0000 [thread overview]
Message-ID: <C37D651A908B024F974696C65296B57B0F4CFB61@SHSMSX101.ccr.corp.intel.com> (raw)
In-Reply-To: 1432826207-8428-2-git-send-email-changchun.ouyang@intel.com
On 5/28/2015 11:17 PM, Ouyang, Changchun wrote:
> Vring enqueue need consider the 2 cases:
> 1. Vring descriptors chained together, the first one is for virtio header, the rest are for real
> data, virtio driver in Linux usually use this scheme;
> 2. Only one descriptor, virtio header and real data share one single descriptor, virtio-net pmd use
> such scheme;
For the commit message, :), actually we should consider the desc chain
as logically continuous memory space, so there is also the case like
desc 1: virtio header and data; descs followed: data only.
> So does vring dequeue, it should not assume vring descriptor is chained or not chained, virtio in
> different Linux version has different behavior, e.g. fedora 20 use chained vring descriptor, while
> fedora 21 use one single vring descriptor for tx.
This behavior could be configured. Besides it is not bound to
distribution but virtio-net driver.
They key thing is we should consider the generic case, rather than
fitting the requirement of existing virtio-net implementation, so
suggest remove the above message.
>
> Changes in v2
> - drop the uncompleted packet
> - refine code logic
>
> Signed-off-by: Changchun Ouyang <changchun.ouyang@intel.com>
> ---
> lib/librte_vhost/vhost_rxtx.c | 65 +++++++++++++++++++++++++++++++++----------
> 1 file changed, 50 insertions(+), 15 deletions(-)
>
> diff --git a/lib/librte_vhost/vhost_rxtx.c b/lib/librte_vhost/vhost_rxtx.c
> index 4809d32..06ae2df 100644
> --- a/lib/librte_vhost/vhost_rxtx.c
> +++ b/lib/librte_vhost/vhost_rxtx.c
> @@ -59,7 +59,7 @@ virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
> struct virtio_net_hdr_mrg_rxbuf virtio_hdr = {{0, 0, 0, 0, 0, 0}, 0};
> uint64_t buff_addr = 0;
> uint64_t buff_hdr_addr = 0;
> - uint32_t head[MAX_PKT_BURST], packet_len = 0;
> + uint32_t head[MAX_PKT_BURST];
> uint32_t head_idx, packet_success = 0;
> uint16_t avail_idx, res_cur_idx;
> uint16_t res_base_idx, res_end_idx;
> @@ -113,6 +113,10 @@ virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
> rte_prefetch0(&vq->desc[head[packet_success]]);
>
> while (res_cur_idx != res_end_idx) {
> + uint32_t offset = 0;
> + uint32_t data_len, len_to_cpy;
> + uint8_t hdr = 0, uncompleted_pkt = 0;
> +
> /* Get descriptor from available ring */
> desc = &vq->desc[head[packet_success]];
>
> @@ -125,7 +129,6 @@ virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
>
> /* Copy virtio_hdr to packet and increment buffer address */
> buff_hdr_addr = buff_addr;
> - packet_len = rte_pktmbuf_data_len(buff) + vq->vhost_hlen;
>
> /*
> * If the descriptors are chained the header and data are
> @@ -136,28 +139,55 @@ virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
> desc = &vq->desc[desc->next];
> /* Buffer address translation. */
> buff_addr = gpa_to_vva(dev, desc->addr);
I am wondering if there is the possibility the [GPA, GPA+desc->len]
could cross multiple memory regions.
Don't expect to fix in this patch, :).
> - desc->len = rte_pktmbuf_data_len(buff);
> } else {
> buff_addr += vq->vhost_hlen;
> - desc->len = packet_len;
> + hdr = 1;
> }
>
> + data_len = rte_pktmbuf_data_len(buff);
> + len_to_cpy = RTE_MIN(data_len,
> + hdr ? desc->len - vq->vhost_hlen : desc->len);
> + while (len_to_cpy > 0) {
> + /* Copy mbuf data to buffer */
> + rte_memcpy((void *)(uintptr_t)buff_addr,
> + (const void *)(rte_pktmbuf_mtod(buff, const char *) + offset),
> + len_to_cpy);
> + PRINT_PACKET(dev, (uintptr_t)buff_addr,
> + len_to_cpy, 0);
> +
> + offset += len_to_cpy;
> +
> + if (offset == data_len)
> + break;
I don't understand here. If offset reaches the end of the first segment,
why don't we continue to copy from the next segment?
> +
> + if (desc->flags & VRING_DESC_F_NEXT) {
> + desc = &vq->desc[desc->next];
> + buff_addr = gpa_to_vva(dev, desc->addr);
> + len_to_cpy = RTE_MIN(data_len - offset, desc->len);
> + } else {
> + /* Room in vring buffer is not enough */
> + uncompleted_pkt = 1;
> + break;
> + }
> + };
> +
> /* Update used ring with desc information */
> vq->used->ring[res_cur_idx & (vq->size - 1)].id =
> head[packet_success];
> - vq->used->ring[res_cur_idx & (vq->size - 1)].len = packet_len;
>
> - /* Copy mbuf data to buffer */
> - /* FIXME for sg mbuf and the case that desc couldn't hold the mbuf data */
> - rte_memcpy((void *)(uintptr_t)buff_addr,
> - rte_pktmbuf_mtod(buff, const void *),
> - rte_pktmbuf_data_len(buff));
> - PRINT_PACKET(dev, (uintptr_t)buff_addr,
> - rte_pktmbuf_data_len(buff), 0);
> + /* Drop the packet if it is uncompleted */
> + if (unlikely(uncompleted_pkt == 1))
> + vq->used->ring[res_cur_idx & (vq->size - 1)].len = 0;
> + else
> + vq->used->ring[res_cur_idx & (vq->size - 1)].len =
> + offset + vq->vhost_hlen;
>
> res_cur_idx++;
> packet_success++;
>
> + if (unlikely(uncompleted_pkt == 1))
> + continue;
> +
> rte_memcpy((void *)(uintptr_t)buff_hdr_addr,
> (const void *)&virtio_hdr, vq->vhost_hlen);
>
> @@ -589,7 +619,14 @@ rte_vhost_dequeue_burst(struct virtio_net *dev, uint16_t queue_id,
> desc = &vq->desc[head[entry_success]];
>
> /* Discard first buffer as it is the virtio header */
> - desc = &vq->desc[desc->next];
> + if (desc->flags & VRING_DESC_F_NEXT) {
> + desc = &vq->desc[desc->next];
> + vb_offset = 0;
> + vb_avail = desc->len;
> + } else {
> + vb_offset = vq->vhost_hlen;
> + vb_avail = desc->len - vb_offset;
> + }
>
> /* Buffer address translation. */
> vb_addr = gpa_to_vva(dev, desc->addr);
> @@ -608,8 +645,6 @@ rte_vhost_dequeue_burst(struct virtio_net *dev, uint16_t queue_id,
> vq->used->ring[used_idx].id = head[entry_success];
> vq->used->ring[used_idx].len = 0;
>
> - vb_offset = 0;
> - vb_avail = desc->len;
> /* Allocate an mbuf and populate the structure. */
> m = rte_pktmbuf_alloc(mbuf_pool);
> if (unlikely(m == NULL)) {
next prev parent reply other threads:[~2015-05-31 5:03 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-04 6:26 [PATCH] virtio: Fix enqueue/dequeue can't handle chained vring descriptors Ouyang Changchun
2015-05-12 10:00 ` Thomas Monjalon
2015-05-18 9:39 ` Xie, Huawei
2015-05-18 13:23 ` Ouyang, Changchun
2015-05-20 5:26 ` Xie, Huawei
2015-05-28 15:16 ` [PATCH v2 0/5] Fix vhost enqueue/dequeue issue Ouyang Changchun
2015-05-28 15:16 ` [PATCH v2 1/5] lib_vhost: Fix enqueue/dequeue can't handle chained vring descriptors Ouyang Changchun
2015-05-31 5:03 ` Xie, Huawei [this message]
2015-05-31 13:20 ` Ouyang, Changchun
2015-05-31 8:40 ` Xie, Huawei
2015-05-31 12:59 ` Ouyang, Changchun
2015-05-31 13:22 ` Ouyang, Changchun
2015-05-31 13:33 ` Ouyang, Changchun
2015-05-28 15:16 ` [PATCH v2 2/5] lib_vhost: Refine code style Ouyang Changchun
2015-05-28 15:16 ` [PATCH v2 3/5] lib_vhost: Extract function Ouyang Changchun
2015-05-28 15:16 ` [PATCH v2 4/5] lib_vhost: Remove unnecessary vring descriptor length updating Ouyang Changchun
2015-05-28 15:16 ` [PATCH v2 5/5] lib_vhost: Add support copying scattered mbuf to vring Ouyang Changchun
2015-05-31 9:10 ` Xie, Huawei
2015-05-31 13:07 ` Ouyang, Changchun
2015-06-01 8:25 ` [PATCH v3 0/4] Fix vhost enqueue/dequeue issue Ouyang Changchun
2015-06-01 8:25 ` [PATCH v3 1/4] lib_vhost: Fix enqueue/dequeue can't handle chained vring descriptors Ouyang Changchun
2015-06-02 7:51 ` Xie, Huawei
2015-06-02 8:10 ` Ouyang, Changchun
2015-06-01 8:25 ` [PATCH v3 2/4] lib_vhost: Refine code style Ouyang Changchun
2015-06-01 8:25 ` [PATCH v3 3/4] lib_vhost: Extract function Ouyang Changchun
2015-06-01 8:25 ` [PATCH v3 4/4] lib_vhost: Remove unnecessary vring descriptor length updating Ouyang Changchun
2015-06-02 8:51 ` [PATCH v4 0/4] Fix vhost enqueue/dequeue issue Ouyang Changchun
2015-06-02 8:51 ` [PATCH v4 1/4] lib_vhost: Fix enqueue/dequeue can't handle chained vring descriptors Ouyang Changchun
2015-06-02 8:51 ` [PATCH v4 2/4] lib_vhost: Refine code style Ouyang Changchun
2015-06-02 8:51 ` [PATCH v4 3/4] lib_vhost: Extract function Ouyang Changchun
2015-06-02 8:51 ` [PATCH v4 4/4] lib_vhost: Remove unnecessary vring descriptor length updating Ouyang Changchun
2015-06-03 6:02 ` [PATCH v5 0/4] Fix vhost enqueue/dequeue issue Ouyang Changchun
2015-06-03 6:02 ` [PATCH v5 1/4] lib_vhost: Fix enqueue/dequeue can't handle chained vring descriptors Ouyang Changchun
2015-06-03 6:02 ` [PATCH v5 2/4] lib_vhost: Refine code style Ouyang Changchun
2015-06-03 6:02 ` [PATCH v5 3/4] lib_vhost: Extract function Ouyang Changchun
2015-06-03 6:02 ` [PATCH v5 4/4] lib_vhost: Remove unnecessary vring descriptor length updating Ouyang Changchun
2015-06-03 7:50 ` [PATCH v5 0/4] Fix vhost enqueue/dequeue issue Xu, Qian Q
2015-06-08 3:18 ` [PATCH v6 " Ouyang Changchun
2015-06-08 3:18 ` [PATCH v6 1/4] lib_vhost: Fix enqueue/dequeue can't handle chained vring descriptors Ouyang Changchun
2015-06-08 3:18 ` [PATCH v6 2/4] lib_vhost: Refine code style Ouyang Changchun
2015-06-08 3:18 ` [PATCH v6 3/4] lib_vhost: Extract function Ouyang Changchun
2015-06-08 3:18 ` [PATCH v6 4/4] lib_vhost: Remove unnecessary vring descriptor length updating Ouyang Changchun
2015-06-09 1:03 ` [PATCH v7 0/4] Fix vhost enqueue/dequeue issue Ouyang Changchun
2015-06-09 1:03 ` [PATCH v7 1/4] lib_vhost: Fix enqueue/dequeue can't handle chained vring descriptors Ouyang Changchun
2015-06-09 1:03 ` [PATCH v7 2/4] lib_vhost: Refine code style Ouyang Changchun
2015-06-09 1:03 ` [PATCH v7 3/4] lib_vhost: Extract function Ouyang Changchun
2015-06-09 1:03 ` [PATCH v7 4/4] lib_vhost: Remove unnecessary vring descriptor length updating Ouyang Changchun
2015-06-10 1:40 ` [PATCH v7 0/4] Fix vhost enqueue/dequeue issue Xie, Huawei
2015-06-10 6:49 ` Xie, Huawei
2015-06-17 14:57 ` Thomas Monjalon
2015-06-15 9:42 ` Thomas Monjalon
2015-06-16 1:01 ` Ouyang, Changchun
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