Subject: [PATCH net-next 2/4] sfc: allocate rx pages on the same node as the interrupt

From: Shradha Shah <[email-masked]>
Date: Wed, 28 Oct 2015 15:01:42 +0000

From: Daniel Pieczko <[email-masked]>

When the interrupt servicing a channel is on a NUMA node that is
not local to the device, performance is improved by allocating
rx pages on the node local to the interrupt (remote to the device)

The performance-optimal case, where interrupts and applications
are pinned to CPUs on the same node as the device, is not altered
by this change.

This change gave a 1% improvement in transaction rate using Nginx
with all interrupts and Nginx threads on the node remote to the
device. It also gave a small reduction in round-trip latency,
again with the interrupt and application on a different node to
the device.

Allocating rx pages based on the channel->irq_node value is only
valid for the initial driver-load interrupt affinities; if an
interrupt is moved later, the wrong node may be used for the
allocation.

Signed-off-by: Shradha Shah <[email-masked]>
---
 drivers/net/ethernet/sfc/efx.c        |  1 +
 drivers/net/ethernet/sfc/net_driver.h |  3 +++
 drivers/net/ethernet/sfc/rx.c         | 14 +++++++++-----
 3 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/sfc/efx.c b/drivers/net/ethernet/sfc/efx.c
index 974637d..89fbd03 100644
--- a/drivers/net/ethernet/sfc/efx.c
+++ b/drivers/net/ethernet/sfc/efx.c
@@ -445,6 +445,7 @@ efx_alloc_channel(struct efx_nic *efx, int i, struct efx_channel *old_channel)
 	channel->efx = efx;
 	channel->channel = i;
 	channel->type = &efx_default_channel_type;
+	channel->irq_node = NUMA_NO_NODE;
 
 	for (j = 0; j < EFX_TXQ_TYPES; j++) {
 		tx_queue = &channel->tx_queue[j];
diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h
index ad56231..0ab9080a 100644
--- a/drivers/net/ethernet/sfc/net_driver.h
+++ b/drivers/net/ethernet/sfc/net_driver.h
@@ -419,6 +419,7 @@ enum efx_sync_events_state {
  * @sync_events_state: Current state of sync events on this channel
  * @sync_timestamp_major: Major part of the last ptp sync event
  * @sync_timestamp_minor: Minor part of the last ptp sync event
+ * @irq_node: NUMA node of interrupt
  */
 struct efx_channel {
 	struct efx_nic *efx;
@@ -477,6 +478,8 @@ struct efx_channel {
 	enum efx_sync_events_state sync_events_state;
 	u32 sync_timestamp_major;
 	u32 sync_timestamp_minor;
+
+	int irq_node;
 };
 
 #ifdef CONFIG_NET_RX_BUSY_POLL
diff --git a/drivers/net/ethernet/sfc/rx.c b/drivers/net/ethernet/sfc/rx.c
index 3f0e129..c5ef1e8 100644
--- a/drivers/net/ethernet/sfc/rx.c
+++ b/drivers/net/ethernet/sfc/rx.c
@@ -168,11 +168,15 @@ static int efx_init_rx_buffers(struct efx_rx_queue *rx_queue, bool atomic)
 			 * context in such a case.  So, use __GFP_NO_WARN
 			 * in case of atomic.
 			 */
-			page = alloc_pages(__GFP_COLD | __GFP_COMP |
-					   (atomic ?
-					    (GFP_ATOMIC | __GFP_NOWARN)
-					    : GFP_KERNEL),
-					   efx->rx_buffer_order);
+			struct efx_channel *channel;
+
+			channel = efx_rx_queue_channel(rx_queue);
+			page = alloc_pages_node(channel->irq_node, __GFP_COMP |
+						(atomic ?
+						 (GFP_ATOMIC | __GFP_NOWARN)
+						 : GFP_KERNEL),
+						efx->rx_buffer_order);
+
 			if (unlikely(page == NULL))
 				return -ENOMEM;
 			dma_addr =