Commit 97cadd3d authored by Alexander Lobakin's avatar Alexander Lobakin Committed by Tony Nguyen
Browse files

iavf: pack iavf_ring more efficiently 



Before replacing the Rx buffer management with libie, clean up
&iavf_ring a bit.
There are several fields not used anywhere in the code -- simply remove
them. Move ::tail up to remove a hole. Replace ::arm_wb boolean with
1-bit flag in ::flags to free 1 more byte. Finally, move ::prev_pkt_ctr
out of &iavf_tx_queue_stats -- it doesn't belong there (used for Tx
stall detection). Place it next to the stats on the ring itself to fill
the 4-byte slot.
The result: no holes and all the hot fields fit into the first 64-byte
cacheline.

Signed-off-by: default avatarAlexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: default avatarTony Nguyen <anthony.l.nguyen@intel.com>
parent e6c91556

drivers/net/ethernet/intel/iavf/iavf_txrx.c

+6 −6
Original line number Diff line number Diff line
@@ -185,7 +185,7 @@ void iavf_detect_recover_hung(struct iavf_vsi *vsi) 
			 * pending work.

			 */

			packets = tx_ring->stats.packets & INT_MAX;

			if (tx_ring->tx_stats.prev_pkt_ctr == packets) {

			if (tx_ring->prev_pkt_ctr == packets) {

				iavf_force_wb(vsi, tx_ring->q_vector);

				continue;

			}
@@ -194,7 +194,7 @@ void iavf_detect_recover_hung(struct iavf_vsi *vsi) 
			 * to iavf_get_tx_pending()

			 */

			smp_rmb();

			tx_ring->tx_stats.prev_pkt_ctr =

			tx_ring->prev_pkt_ctr =

			  iavf_get_tx_pending(tx_ring, true) ? packets : -1;

		}

	}
@@ -320,7 +320,7 @@ static bool iavf_clean_tx_irq(struct iavf_vsi *vsi, 
		    ((j / WB_STRIDE) == 0) && (j > 0) &&

		    !test_bit(__IAVF_VSI_DOWN, vsi->state) &&

		    (IAVF_DESC_UNUSED(tx_ring) != tx_ring->count))

			tx_ring->arm_wb = true;

			tx_ring->flags |= IAVF_TXR_FLAGS_ARM_WB;

	}



	/* notify netdev of completed buffers */
@@ -675,7 +675,7 @@ int iavf_setup_tx_descriptors(struct iavf_ring *tx_ring) 


	tx_ring->next_to_use = 0;

	tx_ring->next_to_clean = 0;

	tx_ring->tx_stats.prev_pkt_ctr = -1;

	tx_ring->prev_pkt_ctr = -1;

	return 0;



err:
@@ -1491,8 +1491,8 @@ int iavf_napi_poll(struct napi_struct *napi, int budget) 
			clean_complete = false;

			continue;

		}

		arm_wb |= ring->arm_wb;

		ring->arm_wb = false;

		arm_wb |= !!(ring->flags & IAVF_TXR_FLAGS_ARM_WB);

		ring->flags &= ~IAVF_TXR_FLAGS_ARM_WB;

	}



	/* Handle case where we are called by netpoll with a budget of 0 */

drivers/net/ethernet/intel/iavf/iavf_txrx.h

+3 −19
Original line number Diff line number Diff line
@@ -227,7 +227,6 @@ struct iavf_tx_queue_stats { 
	u64 tx_done_old;

	u64 tx_linearize;

	u64 tx_force_wb;

	int prev_pkt_ctr;

	u64 tx_lost_interrupt;

};
@@ -237,12 +236,6 @@ struct iavf_rx_queue_stats { 
	u64 alloc_buff_failed;

};



enum iavf_ring_state_t {

	__IAVF_TX_FDIR_INIT_DONE,

	__IAVF_TX_XPS_INIT_DONE,

	__IAVF_RING_STATE_NBITS /* must be last */

};



/* some useful defines for virtchannel interface, which

 * is the only remaining user of header split

 */
@@ -264,10 +257,8 @@ struct iavf_ring { 
		struct iavf_tx_buffer *tx_bi;

		struct iavf_rx_buffer *rx_bi;

	};

	DECLARE_BITMAP(state, __IAVF_RING_STATE_NBITS);

	u16 queue_index;		/* Queue number of ring */

	u8 dcb_tc;			/* Traffic class of ring */

	u8 __iomem *tail;

	u16 queue_index;		/* Queue number of ring */



	/* high bit set means dynamic, use accessors routines to read/write.

	 * hardware only supports 2us resolution for the ITR registers.
@@ -277,22 +268,14 @@ struct iavf_ring { 
	u16 itr_setting;



	u16 count;			/* Number of descriptors */

	u16 reg_idx;			/* HW register index of the ring */



	/* used in interrupt processing */

	u16 next_to_use;

	u16 next_to_clean;



	u8 atr_sample_rate;

	u8 atr_count;



	bool ring_active;		/* is ring online or not */

	bool arm_wb;		/* do something to arm write back */

	u8 packet_stride;



	u16 flags;

#define IAVF_TXR_FLAGS_WB_ON_ITR		BIT(0)

/* BIT(1) is free, was IAVF_RXR_FLAGS_BUILD_SKB_ENABLED */

#define IAVF_TXR_FLAGS_ARM_WB			BIT(1)

/* BIT(2) is free */

#define IAVF_TXRX_FLAGS_VLAN_TAG_LOC_L2TAG1	BIT(3)

#define IAVF_TXR_FLAGS_VLAN_TAG_LOC_L2TAG2	BIT(4)
@@ -306,6 +289,7 @@ struct iavf_ring { 
		struct iavf_rx_queue_stats rx_stats;

	};



	int prev_pkt_ctr;		/* For Tx stall detection */

	unsigned int size;		/* length of descriptor ring in bytes */

	dma_addr_t dma;			/* physical address of ring */