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Commit d0bfcdfd authored by Alexander Duyck's avatar Alexander Duyck Committed by Jeff Kirsher
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ixgbe: Reorder the ring to q_vector mapping to improve performance 



This change reorders the mapping of rings to q_vectors in the case that the
number of rings exceeds the number of q_vectors.  Previously we would
allocate the first R/N queues to the first q_vector where R is the number
of rings and N is the number of q_vectors.  Instead of doing this we can do
a better job of interleaving the rings to the CPUs by assigning every Nth
ring to the q_vector.

The below tables illustrate this change for the R = 16 N = 4 case.
          Before patch  After patch
q_vector:  0  1  2  3    0  1  2  3
Rings:     0  4  8 12    0  1  2  3
           1  5  9 13    4  5  6  7
           3  6 10 14    8  9 10 11
           4  7 11 15   12 13 14 15

This should improve the performance for both DCB or ATR when the number of
rings exceeds the number of q_vectors allocated by the adapter.

Signed-off-by: default avatarAlexander Duyck <alexander.h.duyck@intel.com>
Tested-by: default avatarRoss Brattain <ross.b.brattain@intel.com>
Signed-off-by: default avatarJeff Kirsher <jeffrey.t.kirsher@intel.com>
parent a4d4f629

drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c

+20 −15
Original line number Diff line number Diff line
@@ -523,11 +523,17 @@ static void ixgbe_add_ring(struct ixgbe_ring *ring, 
/**

 * ixgbe_alloc_q_vector - Allocate memory for a single interrupt vector

 * @adapter: board private structure to initialize

 * @v_count: q_vectors allocated on adapter, used for ring interleaving

 * @v_idx: index of vector in adapter struct

 * @txr_count: total number of Tx rings to allocate

 * @txr_idx: index of first Tx ring to allocate

 * @rxr_count: total number of Rx rings to allocate

 * @rxr_idx: index of first Rx ring to allocate

 *

 * We allocate one q_vector.  If allocation fails we return -ENOMEM.

 **/

static int ixgbe_alloc_q_vector(struct ixgbe_adapter *adapter, int v_idx,

static int ixgbe_alloc_q_vector(struct ixgbe_adapter *adapter,

				int v_count, int v_idx,

				int txr_count, int txr_idx,

				int rxr_count, int rxr_idx)

{
@@ -598,7 +604,7 @@ static int ixgbe_alloc_q_vector(struct ixgbe_adapter *adapter, int v_idx, 


		/* update count and index */

		txr_count--;

		txr_idx++;

		txr_idx += v_count;



		/* push pointer to next ring */

		ring++;
@@ -641,7 +647,7 @@ static int ixgbe_alloc_q_vector(struct ixgbe_adapter *adapter, int v_idx, 


		/* update count and index */

		rxr_count--;

		rxr_idx++;

		rxr_idx += v_count;



		/* push pointer to next ring */

		ring++;
@@ -700,24 +706,23 @@ static int ixgbe_alloc_q_vectors(struct ixgbe_adapter *adapter) 
		q_vectors = 1;



	if (q_vectors >= (rxr_remaining + txr_remaining)) {

		for (; rxr_remaining; v_idx++, q_vectors--) {

			int rqpv = DIV_ROUND_UP(rxr_remaining, q_vectors);

			err = ixgbe_alloc_q_vector(adapter, v_idx,

						   0, 0, rqpv, rxr_idx);

		for (; rxr_remaining; v_idx++) {

			err = ixgbe_alloc_q_vector(adapter, q_vectors, v_idx,

						   0, 0, 1, rxr_idx);



			if (err)

				goto err_out;



			/* update counts and index */

			rxr_remaining -= rqpv;

			rxr_idx += rqpv;

			rxr_remaining--;

			rxr_idx++;

		}

	}



	for (; q_vectors; v_idx++, q_vectors--) {

		int rqpv = DIV_ROUND_UP(rxr_remaining, q_vectors);

		int tqpv = DIV_ROUND_UP(txr_remaining, q_vectors);

		err = ixgbe_alloc_q_vector(adapter, v_idx,

	for (; v_idx < q_vectors; v_idx++) {

		int rqpv = DIV_ROUND_UP(rxr_remaining, q_vectors - v_idx);

		int tqpv = DIV_ROUND_UP(txr_remaining, q_vectors - v_idx);

		err = ixgbe_alloc_q_vector(adapter, q_vectors, v_idx,

					   tqpv, txr_idx,

					   rqpv, rxr_idx);
@@ -726,9 +731,9 @@ static int ixgbe_alloc_q_vectors(struct ixgbe_adapter *adapter) 


		/* update counts and index */

		rxr_remaining -= rqpv;

		rxr_idx += rqpv;

		txr_remaining -= tqpv;

		txr_idx += tqpv;

		rxr_idx++;

		txr_idx++;

	}



	return 0;