Re: [PATCH v4 1/3] ethdev: introduce maximum Rx buffer size

["lihuisong (C)" <lihuisong@huawei.com>]

在 2023/11/3 0:35, Ferruh Yigit 写道:
> On 11/2/2023 12:16 PM, Huisong Li wrote:
>> The "min_rx_bufsize" in struct rte_eth_dev_info stands for the minimum
>> Rx buffer size supported by hardware. Actually, some engines also have
>> the maximum Rx buffer specification, like, hns3, i40e and so on. If mbuf
>> data room size in mempool is greater then the maximum Rx buffer size
>> per descriptor supported by HW, the data size application used in each
>> mbuf is just as much as the maximum Rx buffer size instead of the whole
>> data room size.
>>
>> So introduce maximum Rx buffer size which is not enforced just to
>> report user to avoid memory waste. In addition, fix the comment for
>> the "min_rx_bufsize" to make it be more specific.
>>
>> Signed-off-by: Huisong Li <lihuisong@huawei.com>
>> Acked-by: Chengwen Feng <fengchengwen@huawei.com>
>> Acked-by: Morten Brørup <mb@smartsharesystems.com>
>> ---
>>   doc/guides/rel_notes/release_23_11.rst |  7 +++++++
>>   lib/ethdev/rte_ethdev.c                |  7 +++++++
>>   lib/ethdev/rte_ethdev.h                | 10 +++++++++-
>>   3 files changed, 23 insertions(+), 1 deletion(-)
>>
>> diff --git a/doc/guides/rel_notes/release_23_11.rst b/doc/guides/rel_notes/release_23_11.rst
>> index 95db98d098..d4f7d5b266 100644
>> --- a/doc/guides/rel_notes/release_23_11.rst
>> +++ b/doc/guides/rel_notes/release_23_11.rst
>> @@ -122,6 +122,13 @@ New Features
>>     a group's miss actions, which are the actions to be performed on packets
>>     that didn't match any of the flow rules in the group.
>>   
>> +* **Added maximum Rx buffer size to report.**
>> +
>> +  Introduced the ``max_rx_bufsize`` field representing the maximum Rx
>> +  buffer size per descriptor supported by HW in structure ``rte_eth_dev_info``
>> +  to report user and to avoid wasting space of mempool.
>> +  Its value is UINT32_MAX if driver doesn't report it.
>> +
>>   * **Updated Amazon ena (Elastic Network Adapter) net driver.**
>>   
>>     * Upgraded ENA HAL to latest version.
>> diff --git a/lib/ethdev/rte_ethdev.c b/lib/ethdev/rte_ethdev.c
>> index af23ac0ad0..03539bb6c3 100644
>> --- a/lib/ethdev/rte_ethdev.c
>> +++ b/lib/ethdev/rte_ethdev.c
>> @@ -2112,6 +2112,7 @@ rte_eth_rx_queue_setup(uint16_t port_id, uint16_t rx_queue_id,
>>   	struct rte_eth_dev *dev;
>>   	struct rte_eth_dev_info dev_info;
>>   	struct rte_eth_rxconf local_conf;
>> +	uint32_t vld_bufsize;
>>   
> I guess 'vld' is valid, but that is not accurate. Can we rename it
> something like 'buf_data_size'?
Ack
>
>>   	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
>>   	dev = &rte_eth_devices[port_id];
>> @@ -2158,6 +2159,11 @@ rte_eth_rx_queue_setup(uint16_t port_id, uint16_t rx_queue_id,
>>   			return ret;
>>   
>>   		mbp_buf_size = rte_pktmbuf_data_room_size(mp);
>> +		vld_bufsize = mbp_buf_size - RTE_PKTMBUF_HEADROOM;
>> +		if (vld_bufsize > dev_info.max_rx_bufsize)
>> +			RTE_ETHDEV_LOG(INFO,
>> +				"For port_id=%u the max data size per mbuf in Rx is %u instead of the whole data room(%u).\n",
>> +				port_id, dev_info.max_rx_bufsize, vld_bufsize);
>>
> This log gives some information, but it is not clear what user should
> do. My concern is this can confuse end users (not developers but users
> of dpdk application).
>
> Since audience of this message is DPDK application developer, most of
> the times end user don't have anything to do with this log, what do you
> think to change log level to 'debug'?
Ack
>
> Also can we add some action to it, something like:
> "mbuf data buffer size is bigger than what device can utilize, consider
> reducing mbuf size."
What do you think of this log, Ferruh?
"The mbuf data buffer size (%u) is bigger than the max size (%u) device 
with port_id=%u can utilize, consider reducing mbuf size.\n",
>
>
>
>>   	} else if (rx_conf != NULL && rx_conf->rx_nseg > 0) {
>>   		const struct rte_eth_rxseg_split *rx_seg;
>>   		uint16_t n_seg;
>> @@ -3757,6 +3763,7 @@ rte_eth_dev_info_get(uint16_t port_id, struct rte_eth_dev_info *dev_info)
>>   	dev_info->min_mtu = RTE_ETHER_MIN_LEN - RTE_ETHER_HDR_LEN -
>>   		RTE_ETHER_CRC_LEN;
>>   	dev_info->max_mtu = UINT16_MAX;
>> +	dev_info->max_rx_bufsize = UINT32_MAX;
>>   
>>   	if (*dev->dev_ops->dev_infos_get == NULL)
>>   		return -ENOTSUP;
>> diff --git a/lib/ethdev/rte_ethdev.h b/lib/ethdev/rte_ethdev.h
>> index a53dd5a1ef..7133b73d26 100644
>> --- a/lib/ethdev/rte_ethdev.h
>> +++ b/lib/ethdev/rte_ethdev.h
>> @@ -1723,7 +1723,15 @@ struct rte_eth_dev_info {
>>   	uint16_t min_mtu;	/**< Minimum MTU allowed */
>>   	uint16_t max_mtu;	/**< Maximum MTU allowed */
>>   	const uint32_t *dev_flags; /**< Device flags */
>> -	uint32_t min_rx_bufsize; /**< Minimum size of Rx buffer. */
>> +	/** Minimum Rx buffer size per descriptor supported by HW. */
>> +	uint32_t min_rx_bufsize;
>> +	/**
>> +	 * Maximum Rx buffer size per descriptor supported by HW.
>> +	 * The value is not enforced, information only to application to
>> +	 * optimize mbuf size. Its value is UINT32_MAX when not specified
>> +	 * by the driver.
>> +	 */
>> +	uint32_t max_rx_bufsize;
>>   	uint32_t max_rx_pktlen; /**< Maximum configurable length of Rx pkt. */
>>   	/** Maximum configurable size of LRO aggregated packet. */
>>   	uint32_t max_lro_pkt_size;
> .