ixgbe: DCB, use multiple Tx rings per traffic class
This enables multiple {Tx|Rx} rings per traffic class while in DCB mode. In order to get this working as expected the tc_to_tx net device mapping is configured as well as the prio_tc_map. skb priorities are mapped across a range of queue pairs to get a distribution per traffic class. The maximum number of queue pairs used while in DCB mode is capped at 64. The hardware max is actually 128 queues but 64 is sufficient for now and allocating more seemed a bit excessive. It is easy enough to increase the cap later if need be. To get the 802.1Q priority tags inserted correctly ixgbe was previously using the skb queue_mapping field to directly set the 802.1Q priority. This no longer works because we have removed the 1:1 mapping between queues and traffic class. Each ring is aligned with an 802.1Qaz traffic class so here we add an extra field to the ring struct to identify the 802.1Q traffic class. This uses an extra byte of the ixgbe_ring struct fortunately there was a 2byte hole, struct ixgbe_ring { void * desc; /* 0 8 */ struct device * dev; /* 8 8 */ struct net_device * netdev; /* 16 8 */ union { struct ixgbe_tx_buffer * tx_buffer_info; /* 8 */ struct ixgbe_rx_buffer * rx_buffer_info; /* 8 */ }; /* 24 8 */ long unsigned int state; /* 32 8 */ u8 atr_sample_rate; /* 40 1 */ u8 atr_count; /* 41 1 */ u16 count; /* 42 2 */ u16 rx_buf_len; /* 44 2 */ u16 next_to_use; /* 46 2 */ u16 next_to_clean; /* 48 2 */ u8 queue_index; /* 50 1 */ u8 reg_idx; /* 51 1 */ u16 work_limit; /* 52 2 */ /* XXX 2 bytes hole, try to pack */ u8 * tail; /* 56 8 */ /* --- cacheline 1 boundary (64 bytes) --- */ Now we can set the VLAN priority directly and it will be correct. User space can indicate the 802.1Qaz priority using the SO_PRIORITY setsocket() option and QOS layer will steer the skb to the correct rings. Additionally using the multiq qdisc with a queue_mapping action works as well. Signed-off-by: John Fastabend <john.r.fastabend@intel.com> Tested-by: Ross Brattain <ross.b.brattain@intel.com> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
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