From: "Ouyang, Changchun" <changchun.ouyang@intel.com>
To: "Xie, Huawei" <huawei.xie@intel.com>, "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH] virtio: Fix enqueue/dequeue can't handle chained vring descriptors.
Date: Mon, 18 May 2015 13:23:12 +0000 [thread overview]
Message-ID: <F52918179C57134FAEC9EA62FA2F962511B4E751@shsmsx102.ccr.corp.intel.com> (raw)
In-Reply-To: <C37D651A908B024F974696C65296B57B0F4A36B3@SHSMSX101.ccr.corp.intel.com>
Hi Huawei,
> -----Original Message-----
> From: Xie, Huawei
> Sent: Monday, May 18, 2015 5:39 PM
> To: Ouyang, Changchun; dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH] virtio: Fix enqueue/dequeue can't handle
> chained vring descriptors.
>
> On 5/4/2015 2:27 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; 2. Only one descriptor, virtio
> > header and real data share one single descriptor;
> >
> > So does vring dequeue.
> >
> > Signed-off-by: Changchun Ouyang <changchun.ouyang@intel.com>
> > ---
> > lib/librte_vhost/vhost_rxtx.c | 60
> > +++++++++++++++++++++++++++++++------------
> > 1 file changed, 44 insertions(+), 16 deletions(-)
> >
> > diff --git a/lib/librte_vhost/vhost_rxtx.c
> > b/lib/librte_vhost/vhost_rxtx.c index 510ffe8..3135883 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 plus_hdr = 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 @@
> > -136,24 +139,44 @@ 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);
> > - desc->len = rte_pktmbuf_data_len(buff);
> > } else {
> > buff_addr += vq->vhost_hlen;
> > - desc->len = packet_len;
> > + plus_hdr = 1;
> > }
> >
> > + data_len = rte_pktmbuf_data_len(buff);
> > + len_to_cpy = RTE_MIN(data_len, desc->len);
> > + do {
> > + if (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);
> > +
> > + desc->len = len_to_cpy + (plus_hdr ? vq-
> >vhost_hlen : 0);
>
> Do we really need to rewrite the desc->len again and again? At least we only
> have the possibility to change the value of desc->len of the last descriptor.
Well, I think we need change each descriptor's len in the chain here,
If aggregate all len to the last descriptor's len, it is possibly the length will exceed its original len,
e.g. use 8 descriptor(each has len of 1024) chained to recv a 8K packet, then last descriptor's len
will be 8K, and all other descriptor is 0, I don't think this situation make sense.
>
> > + offset += len_to_cpy;
> > + 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
> > + break;
>
> Still there are two issues here.
> a) If the data couldn't be fully copied to chain of guest buffers, we shouldn't
> do any copy.
Why don't copy any data is better than the current implementation?
> b) scatter mbuf isn't considered.
If we also consider scatter mbuf here, then this function will have exactly same logic with mergeable_rx,
Do you want to totally remove this function, just keep the mergeable rx function for all cases?
Changchun
next prev parent reply other threads:[~2015-05-18 13:23 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-04 6:26 Ouyang Changchun
2015-05-12 10:00 ` Thomas Monjalon
2015-05-18 9:39 ` Xie, Huawei
2015-05-18 13:23 ` Ouyang, Changchun [this message]
2015-05-20 5:26 ` Xie, Huawei
2015-05-28 15:16 ` [dpdk-dev] [PATCH v2 0/5] Fix vhost enqueue/dequeue issue Ouyang Changchun
2015-05-28 15:16 ` [dpdk-dev] [PATCH v2 1/5] lib_vhost: Fix enqueue/dequeue can't handle chained vring descriptors Ouyang Changchun
2015-05-31 5:03 ` Xie, Huawei
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 ` [dpdk-dev] [PATCH v2 2/5] lib_vhost: Refine code style Ouyang Changchun
2015-05-28 15:16 ` [dpdk-dev] [PATCH v2 3/5] lib_vhost: Extract function Ouyang Changchun
2015-05-28 15:16 ` [dpdk-dev] [PATCH v2 4/5] lib_vhost: Remove unnecessary vring descriptor length updating Ouyang Changchun
2015-05-28 15:16 ` [dpdk-dev] [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 ` [dpdk-dev] [PATCH v3 0/4] Fix vhost enqueue/dequeue issue Ouyang Changchun
2015-06-01 8:25 ` [dpdk-dev] [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 ` [dpdk-dev] [PATCH v3 2/4] lib_vhost: Refine code style Ouyang Changchun
2015-06-01 8:25 ` [dpdk-dev] [PATCH v3 3/4] lib_vhost: Extract function Ouyang Changchun
2015-06-01 8:25 ` [dpdk-dev] [PATCH v3 4/4] lib_vhost: Remove unnecessary vring descriptor length updating Ouyang Changchun
2015-06-02 8:51 ` [dpdk-dev] [PATCH v4 0/4] Fix vhost enqueue/dequeue issue Ouyang Changchun
2015-06-02 8:51 ` [dpdk-dev] [PATCH v4 1/4] lib_vhost: Fix enqueue/dequeue can't handle chained vring descriptors Ouyang Changchun
2015-06-02 8:51 ` [dpdk-dev] [PATCH v4 2/4] lib_vhost: Refine code style Ouyang Changchun
2015-06-02 8:51 ` [dpdk-dev] [PATCH v4 3/4] lib_vhost: Extract function Ouyang Changchun
2015-06-02 8:51 ` [dpdk-dev] [PATCH v4 4/4] lib_vhost: Remove unnecessary vring descriptor length updating Ouyang Changchun
2015-06-03 6:02 ` [dpdk-dev] [PATCH v5 0/4] Fix vhost enqueue/dequeue issue Ouyang Changchun
2015-06-03 6:02 ` [dpdk-dev] [PATCH v5 1/4] lib_vhost: Fix enqueue/dequeue can't handle chained vring descriptors Ouyang Changchun
2015-06-03 6:02 ` [dpdk-dev] [PATCH v5 2/4] lib_vhost: Refine code style Ouyang Changchun
2015-06-03 6:02 ` [dpdk-dev] [PATCH v5 3/4] lib_vhost: Extract function Ouyang Changchun
2015-06-03 6:02 ` [dpdk-dev] [PATCH v5 4/4] lib_vhost: Remove unnecessary vring descriptor length updating Ouyang Changchun
2015-06-03 7:50 ` [dpdk-dev] [PATCH v5 0/4] Fix vhost enqueue/dequeue issue Xu, Qian Q
2015-06-08 3:18 ` [dpdk-dev] [PATCH v6 " Ouyang Changchun
2015-06-08 3:18 ` [dpdk-dev] [PATCH v6 1/4] lib_vhost: Fix enqueue/dequeue can't handle chained vring descriptors Ouyang Changchun
2015-06-08 3:18 ` [dpdk-dev] [PATCH v6 2/4] lib_vhost: Refine code style Ouyang Changchun
2015-06-08 3:18 ` [dpdk-dev] [PATCH v6 3/4] lib_vhost: Extract function Ouyang Changchun
2015-06-08 3:18 ` [dpdk-dev] [PATCH v6 4/4] lib_vhost: Remove unnecessary vring descriptor length updating Ouyang Changchun
2015-06-09 1:03 ` [dpdk-dev] [PATCH v7 0/4] Fix vhost enqueue/dequeue issue Ouyang Changchun
2015-06-09 1:03 ` [dpdk-dev] [PATCH v7 1/4] lib_vhost: Fix enqueue/dequeue can't handle chained vring descriptors Ouyang Changchun
2015-06-09 1:03 ` [dpdk-dev] [PATCH v7 2/4] lib_vhost: Refine code style Ouyang Changchun
2015-06-09 1:03 ` [dpdk-dev] [PATCH v7 3/4] lib_vhost: Extract function Ouyang Changchun
2015-06-09 1:03 ` [dpdk-dev] [PATCH v7 4/4] lib_vhost: Remove unnecessary vring descriptor length updating Ouyang Changchun
2015-06-10 1:40 ` [dpdk-dev] [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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