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From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: "Xia, Chenbo" <chenbo.xia@intel.com>,
	"dev@dpdk.org" <dev@dpdk.org>,
	"amorenoz@redhat.com" <amorenoz@redhat.com>,
	"david.marchand@redhat.com" <david.marchand@redhat.com>,
	"olivier.matz@6wind.com" <olivier.matz@6wind.com>
Subject: Re: [dpdk-dev] [PATCH 2/3] net/virtio: allocate fake mbuf in Rx queue
Date: Mon, 15 Mar 2021 12:29:26 +0100
Message-ID: <58fb579b-6186-7018-e5a3-d9bb887475d5@redhat.com> (raw)
In-Reply-To: <MN2PR11MB4063B5D954B714FCFCC0F0349CAB0@MN2PR11MB4063.namprd11.prod.outlook.com>



On 1/11/21 3:50 AM, Xia, Chenbo wrote:
> Hi Maxime,
> 
>> -----Original Message-----
>> From: Maxime Coquelin <maxime.coquelin@redhat.com>
>> Sent: Tuesday, December 22, 2020 12:15 AM
>> To: dev@dpdk.org; Xia, Chenbo <chenbo.xia@intel.com>; amorenoz@redhat.com;
>> david.marchand@redhat.com; olivier.matz@6wind.com
>> Cc: Maxime Coquelin <maxime.coquelin@redhat.com>
>> Subject: [PATCH 2/3] net/virtio: allocate fake mbuf in Rx queue
>>
>> While it is worth clarifying whether the fake mbuf
>> in virtnet_rx struct is really necessary, it is sure
>> that it heavily impacts cache usage by being part of
>> the struct. Indeed, it takes uses cachelines, and
> 
> Did you mean 'uses cachelines'?

I don't know what I meant here :) I will rework it!

>> requires alignement on a cacheline.
> 
> Alignment?
> 
> With above fixed:
> 
> Reviewed-by: Chenbo Xia <chenbo.xia@intel.com>
> 
>>
>> Before this series, it means it took 120 bytes in
>> virtnet_rx struct:
>>
>> struct virtnet_rx {
>> 	struct virtqueue *         vq;                   /*     0     8 */
>>
>> 	/* XXX 56 bytes hole, try to pack */
>>
>> 	/* --- cacheline 1 boundary (64 bytes) --- */
>> 	struct rte_mbuf            fake_mbuf __attribute__((__aligned__(64)));
>> /*    64   128 */
>> 	/* --- cacheline 3 boundary (192 bytes) --- */
>>
>> This patch allocates it using malloc in order to optimize
>> virtnet_rx cache usage and so virtqueue cache usage.
>>
>> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
>> ---
>>  drivers/net/virtio/virtio_ethdev.c | 10 ++++++++++
>>  drivers/net/virtio/virtio_rxtx.c   |  8 +++-----
>>  drivers/net/virtio/virtio_rxtx.h   |  2 +-
>>  3 files changed, 14 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/net/virtio/virtio_ethdev.c
>> b/drivers/net/virtio/virtio_ethdev.c
>> index 297c01a70d..a1351b36ca 100644
>> --- a/drivers/net/virtio/virtio_ethdev.c
>> +++ b/drivers/net/virtio/virtio_ethdev.c
>> @@ -539,6 +539,7 @@ virtio_init_queue(struct rte_eth_dev *dev, uint16_t
>> queue_idx)
>>  	}
>>
>>  	if (queue_type == VTNET_RQ) {
>> +		struct rte_mbuf *fake_mbuf;
>>  		size_t sz_sw = (RTE_PMD_VIRTIO_RX_MAX_BURST + vq_size) *
>>  			       sizeof(vq->sw_ring[0]);
>>
>> @@ -550,10 +551,18 @@ virtio_init_queue(struct rte_eth_dev *dev, uint16_t
>> queue_idx)
>>  			goto fail_q_alloc;
>>  		}
>>
>> +		fake_mbuf = malloc(sizeof(*fake_mbuf));
>> +		if (!fake_mbuf) {
>> +			PMD_INIT_LOG(ERR, "can not allocate fake mbuf");
>> +			ret = -ENOMEM;
>> +			goto fail_q_alloc;
>> +		}
>> +
>>  		vq->sw_ring = sw_ring;
>>  		rxvq = &vq->rxq;
>>  		rxvq->port_id = dev->data->port_id;
>>  		rxvq->mz = mz;
>> +		rxvq->fake_mbuf = fake_mbuf;
>>  	} else if (queue_type == VTNET_TQ) {
>>  		txvq = &vq->txq;
>>  		txvq->port_id = dev->data->port_id;
>> @@ -636,6 +645,7 @@ virtio_free_queues(struct virtio_hw *hw)
>>
>>  		queue_type = virtio_get_queue_type(hw, i);
>>  		if (queue_type == VTNET_RQ) {
>> +			free(vq->rxq.fake_mbuf);
>>  			rte_free(vq->sw_ring);
>>  			rte_memzone_free(vq->rxq.mz);
>>  		} else if (queue_type == VTNET_TQ) {
>> diff --git a/drivers/net/virtio/virtio_rxtx.c
>> b/drivers/net/virtio/virtio_rxtx.c
>> index 1fcce36cbd..d147d7300a 100644
>> --- a/drivers/net/virtio/virtio_rxtx.c
>> +++ b/drivers/net/virtio/virtio_rxtx.c
>> @@ -703,11 +703,9 @@ virtio_dev_rx_queue_setup_finish(struct rte_eth_dev *dev,
>> uint16_t queue_idx)
>>  		virtio_rxq_vec_setup(rxvq);
>>  	}
>>
>> -	memset(&rxvq->fake_mbuf, 0, sizeof(rxvq->fake_mbuf));
>> -	for (desc_idx = 0; desc_idx < RTE_PMD_VIRTIO_RX_MAX_BURST;
>> -	     desc_idx++) {
>> -		vq->sw_ring[vq->vq_nentries + desc_idx] =
>> -			&rxvq->fake_mbuf;
>> +	memset(rxvq->fake_mbuf, 0, sizeof(*rxvq->fake_mbuf));
>> +	for (desc_idx = 0; desc_idx < RTE_PMD_VIRTIO_RX_MAX_BURST; desc_idx++) {
>> +		vq->sw_ring[vq->vq_nentries + desc_idx] = rxvq->fake_mbuf;
>>  	}
>>
>>  	if (hw->use_vec_rx && !virtio_with_packed_queue(hw)) {
>> diff --git a/drivers/net/virtio/virtio_rxtx.h
>> b/drivers/net/virtio/virtio_rxtx.h
>> index 7f1036be6f..6ce5d67d15 100644
>> --- a/drivers/net/virtio/virtio_rxtx.h
>> +++ b/drivers/net/virtio/virtio_rxtx.h
>> @@ -19,7 +19,7 @@ struct virtnet_stats {
>>
>>  struct virtnet_rx {
>>  	/* dummy mbuf, for wraparound when processing RX ring. */
>> -	struct rte_mbuf fake_mbuf;
>> +	struct rte_mbuf *fake_mbuf;
>>  	uint64_t mbuf_initializer; /**< value to init mbufs. */
>>  	struct rte_mempool *mpool; /**< mempool for mbuf allocation */
>>
>> --
>> 2.29.2
> 


  reply	other threads:[~2021-03-15 11:29 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-21 16:14 [dpdk-dev] [PATCH 0/3] net/virtio: make virtqueue struct cache-friendly Maxime Coquelin
2020-12-21 16:14 ` [dpdk-dev] [PATCH 1/3] net/virtio: remove reference to virtqueue in vrings Maxime Coquelin
2021-01-11  2:17   ` Xia, Chenbo
2020-12-21 16:14 ` [dpdk-dev] [PATCH 2/3] net/virtio: allocate fake mbuf in Rx queue Maxime Coquelin
2021-01-11  2:50   ` Xia, Chenbo
2021-03-15 11:29     ` Maxime Coquelin [this message]
2021-01-11  5:39   ` Xia, Chenbo
2021-03-15 13:46     ` Maxime Coquelin
2020-12-21 16:14 ` [dpdk-dev] [PATCH 3/3] net/virtio: pack virtuqueue struct Maxime Coquelin
2021-01-11  2:56   ` Xia, Chenbo
2021-01-08  2:50 ` [dpdk-dev] [PATCH 0/3] net/virtio: make virtqueue struct cache-friendly Xia, Chenbo
2021-01-08  8:25   ` Maxime Coquelin
2021-01-25 17:30 ` Maxime Coquelin

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