From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: Tiwei Bie <tiwei.bie@intel.com>
Cc: zhihong.wang@intel.com, jfreimann@redhat.com, dev@dpdk.org,
mst@redhat.com, jasowang@redhat.com, wexu@redhat.com
Subject: Re: [dpdk-dev] [PATCH v6 07/15] vhost: extract split ring handling from Rx and Tx functions
Date: Wed, 4 Jul 2018 23:04:18 +0200 [thread overview]
Message-ID: <bf755c9f-31cf-b7b1-1e11-fbba1dcac8f3@redhat.com> (raw)
In-Reply-To: <20180704065136.GA617@debian>
On 07/04/2018 08:51 AM, Tiwei Bie wrote:
> On Mon, Jul 02, 2018 at 10:16:21AM +0200, Maxime Coquelin wrote:
> [...]
>> +
>> + if (unlikely(vq->access_ok == 0))
>> + if (unlikely(vring_translate(dev, vq) < 0))
>> + goto out;
>> +
>> +
>
> Please just keep one blank line.
>
>> + /*
>> + * Construct a RARP broadcast packet, and inject it to the "pkts"
>> + * array, to looks like that guest actually send such packet.
>> + *
>> + * Check user_send_rarp() for more information.
>> + *
>> + * broadcast_rarp shares a cacheline in the virtio_net structure
>> + * with some fields that are accessed during enqueue and
>> + * rte_atomic16_cmpset() causes a write if using cmpxchg. This could
>> + * result in false sharing between enqueue and dequeue.
>> + *
>> + * Prevent unnecessary false sharing by reading broadcast_rarp first
>> + * and only performing cmpset if the read indicates it is likely to
>> + * be set.
>> + */
>> +
>
> Please remove above blank line.
>
>> + if (unlikely(rte_atomic16_read(&dev->broadcast_rarp) &&
>> + rte_atomic16_cmpset((volatile uint16_t *)
>> + &dev->broadcast_rarp.cnt, 1, 0))) {
>> +
>> + rarp_mbuf = rte_net_make_rarp_packet(mbuf_pool, &dev->mac);
>> + if (rarp_mbuf == NULL) {
>> + RTE_LOG(ERR, VHOST_DATA,
>> + "Failed to make RARP packet.\n");
>> + return 0;
>> + }
>> + count -= 1;
>> + }
>> +
>> + count = virtio_dev_tx_split(dev, vq, mbuf_pool, pkts, count);
>> +
>> out:
>> if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))
>> vhost_user_iotlb_rd_unlock(vq);
>> @@ -1200,10 +1222,10 @@ rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
>> * Inject it to the head of "pkts" array, so that switch's mac
>> * learning table will get updated first.
>> */
>> - memmove(&pkts[1], pkts, i * sizeof(struct rte_mbuf *));
>> + memmove(&pkts[1], pkts, count * sizeof(struct rte_mbuf *));
>> pkts[0] = rarp_mbuf;
>> - i += 1;
>> + count += 1;
>> }
>>
>> - return i;
>> + return count;
>> }
>> --
>> 2.14.4
>>
Done,
Thanks,
Maxime
next prev parent reply other threads:[~2018-07-04 21:04 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-02 8:16 [dpdk-dev] [PATCH v6 00/15] Vhost: add support to packed ring layout Maxime Coquelin
2018-07-02 8:16 ` [dpdk-dev] [PATCH v6 01/15] vhost: add virtio packed virtqueue defines Maxime Coquelin
2018-07-04 5:37 ` Tiwei Bie
2018-07-04 16:03 ` Maxime Coquelin
2018-07-02 8:16 ` [dpdk-dev] [PATCH v6 02/15] vhost: add helpers for packed virtqueues Maxime Coquelin
2018-07-04 5:39 ` Tiwei Bie
2018-07-04 16:03 ` Maxime Coquelin
2018-07-02 8:16 ` [dpdk-dev] [PATCH v6 03/15] vhost: vring address setup for packed queues Maxime Coquelin
2018-07-02 8:16 ` [dpdk-dev] [PATCH v6 04/15] vhost: clear shadow used table index at flush time Maxime Coquelin
2018-07-02 8:16 ` [dpdk-dev] [PATCH v6 05/15] vhost: make indirect desc table copy desc type agnostic Maxime Coquelin
2018-07-02 8:16 ` [dpdk-dev] [PATCH v6 06/15] vhost: clear batch copy index at copy time Maxime Coquelin
2018-07-02 8:16 ` [dpdk-dev] [PATCH v6 07/15] vhost: extract split ring handling from Rx and Tx functions Maxime Coquelin
2018-07-04 6:51 ` Tiwei Bie
2018-07-04 21:04 ` Maxime Coquelin [this message]
2018-07-02 8:16 ` [dpdk-dev] [PATCH v6 08/15] vhost: append shadow used ring function names with split Maxime Coquelin
2018-07-02 8:16 ` [dpdk-dev] [PATCH v6 09/15] vhost: add shadow used ring support for packed rings Maxime Coquelin
2018-07-02 8:16 ` [dpdk-dev] [PATCH v6 10/15] vhost: create descriptor mapping function Maxime Coquelin
2018-07-04 5:56 ` Tiwei Bie
2018-07-04 16:18 ` Maxime Coquelin
2018-07-02 8:16 ` [dpdk-dev] [PATCH v6 11/15] vhost: add vector filling support for packed ring Maxime Coquelin
2018-07-04 5:53 ` Tiwei Bie
2018-07-04 16:18 ` Maxime Coquelin
2018-07-02 8:16 ` [dpdk-dev] [PATCH v6 12/15] vhost: add Rx " Maxime Coquelin
2018-07-02 8:16 ` [dpdk-dev] [PATCH v6 13/15] vhost: add Tx " Maxime Coquelin
2018-07-04 5:45 ` Tiwei Bie
2018-07-04 16:09 ` Maxime Coquelin
2018-07-02 8:16 ` [dpdk-dev] [PATCH v6 14/15] vhost: add notification " Maxime Coquelin
2018-07-03 5:57 ` Jason Wang
2018-07-03 6:43 ` Maxime Coquelin
2018-07-03 6:06 ` Jason Wang
2018-07-04 16:02 ` Maxime Coquelin
2018-07-04 6:25 ` Tiwei Bie
2018-07-04 20:20 ` Maxime Coquelin
2018-07-02 8:16 ` [dpdk-dev] [PATCH v6 15/15] vhost: advertize packed ring layout support Maxime Coquelin
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