[ovs-dev] [dpdk-howl PATCH v5 2/2] netdev-dpdk: Set scatter based on capabilities

Eelco Chaudron echaudro at redhat.com
Wed Oct 24 10:41:35 UTC 2018



On 13 Oct 2018, at 23:12, Ophir Munk wrote:

> On , October 12, 2018 12:25 PM Eelco Chaudron wrote:
>
>>
>> On 10 Oct 2018, at 18:14, Ophir Munk wrote:
>>
>>> Before this commit setting scatter offload was based on checking
>>> net_nfp device.
>>> Since DPDK 17.11 more PMD drivers are reporting offload 
>>> capabilities.
>>> Therefore this commit removes the specific check against net_nfp
>>> device and replaces it with a generic check of device capabilities
>>> before setting the scatter offload.
>>>
>>> Signed-off-by: Ophir Munk <ophirmu at mellanox.com>
>>> ---
>>>
>>> v1-v4
>>> This patch was not included in version v1-v4 of the series
>>>
>>> v5
>>> Initial version
>>>
>>>  lib/netdev-dpdk.c | 18 ++++++++++++------
>>>  1 file changed, 12 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c index
>>> 4dd0ec3..ecca276 100644
>>> --- a/lib/netdev-dpdk.c
>>> +++ b/lib/netdev-dpdk.c
>>> @@ -367,6 +367,7 @@ struct ingress_policer {  enum
>> dpdk_hw_ol_features
>>> {
>>>      NETDEV_RX_CHECKSUM_OFFLOAD = 1 << 0,
>>>      NETDEV_RX_HW_CRC_STRIP = 1 << 1,
>>> +    NETDEV_RX_HW_SCATTER = 1 << 2
>>>  };
>>>
>>>  /*
>>> @@ -894,13 +895,11 @@ dpdk_eth_dev_port_config(struct netdev_dpdk
>>> *dev, int n_rxq, int n_txq)
>>>      rte_eth_dev_info_get(dev->port_id, &info);
>>>
>>>      /* As of DPDK 17.11.1 a few PMDs require to explicitly enable
>>> -     * scatter to support jumbo RX. Checking the offload 
>>> capabilities
>>> -     * is not an option as PMDs are not required yet to report
>>> -     * them. The only reliable info is the driver name and 
>>> knowledge
>>> -     * (testing or code review). Listing all such PMDs feels harder
>>> -     * than highlighting the one known not to need scatter */
>>> +     * scatter to support jumbo RX.
>>> +     * Setting scatter for the device is done after checking for
>>> +     * scatter support in the device capabilites. */
>>>      if (dev->mtu > ETHER_MTU) {
>>> -        if (strncmp(info.driver_name, "net_nfp", 7)) {
>>> +        if (dev->hw_ol_features & NETDEV_RX_HW_SCATTER) {
>>>              conf.rxmode.offloads |= DEV_RX_OFFLOAD_SCATTER;
>>>          }
>>>      }
>>> @@ -1035,6 +1034,13 @@ dpdk_eth_dev_init(struct netdev_dpdk *dev)
>>>          dev->hw_ol_features |= NETDEV_RX_CHECKSUM_OFFLOAD;
>>>      }
>>>
>>> +    if (info.rx_offload_capa & DEV_RX_OFFLOAD_SCATTER) {
>>> +        dev->hw_ol_features |= NETDEV_RX_HW_SCATTER;
>>> +    } else {
>>> +        /* Do not warn on lack of scatter support */
>>> +        dev->hw_ol_features &= ~NETDEV_RX_HW_SCATTER;
>>
>> Don’t think we need to clear it explicitly, none of the other 
>> capabilities do
>> this.
>
> The other capabilities do clear explicitly.
> There is a difference between NETDEV_RX_HW_SCATTER flag (which should 
> be set or cleared in dpdk_eth_dev_init()) and DEV_RX_OFFLOAD_SCATTER 
> flag (which is only set in dpdk_eth_dev_port_config()).
>
> Flags of type "NETDEV_RX_XXXXXX" are cleared explicitly. For example, 
> we clear:
> dev->hw_ol_features &= ~NETDEV_RX_HW_CRC_STRIP;
> dev->hw_ol_features &= ~NETDEV_RX_CHECKSUM_OFFLOAD;
>
> in the following code snippet:
>     if (strstr(info.driver_name, "vf") != NULL) {
>         VLOG_INFO("Virtual function detected, HW_CRC_STRIP will be 
> enabled");
>         dev->hw_ol_features |= NETDEV_RX_HW_CRC_STRIP;
>     } else {
>         dev->hw_ol_features &= ~NETDEV_RX_HW_CRC_STRIP;
>     }
>
>     if ((info.rx_offload_capa & rx_chksm_offload_capa) !=
>             rx_chksm_offload_capa) {
>         VLOG_WARN("Rx checksum offload is not supported on port "
>                   DPDK_PORT_ID_FMT, dev->port_id);
>         dev->hw_ol_features &= ~NETDEV_RX_CHECKSUM_OFFLOAD;
>     } else {
>         dev->hw_ol_features |= NETDEV_RX_CHECKSUM_OFFLOAD;
>     }
>
>     if (info.rx_offload_capa & DEV_RX_OFFLOAD_SCATTER) {
>         dev->hw_ol_features |= NETDEV_RX_HW_SCATTER;
>     } else {
>         /* Do not warn on lack of scatter support */
>         dev->hw_ol_features &= ~NETDEV_RX_HW_SCATTER;
>     }
>
> During configuration we only set DEV_RX_OFFLOAD_SCATTER flag:
>     if (dev->mtu > ETHER_MTU) {
>         if (dev->hw_ol_features & NETDEV_RX_HW_SCATTER) {
>             conf.rxmode.offloads |= DEV_RX_OFFLOAD_SCATTER;
>
> I suggest keeping the patch as is.

I agree, and the rest of this patch is fine.

Acked-by: Eelco Chaudron <echaudro at redhat.com>


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