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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: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Ross Brattain <ross.b.brattain@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
This commit is contained in:
Alexander Duyck 2012-03-28 08:03:43 +00:00 committed by Jeff Kirsher
parent a4d4f62916
commit d0bfcdfd48
1 changed files with 20 additions and 15 deletions
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35
drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c
View File

@ -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;