ibmveth: batch rx buffer replacement

At the moment we try and replenish the receive ring on every rx interrupt.
We even have a pool->threshold but aren't using it.

To limit the maximum latency incurred when refilling, change the threshold
from 1/2 to 7/8 and reduce the largest rx pool from 768 buffers to 512 which
should be more than enough.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Santiago Leon <santil@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 5 deletions

diff --git a/drivers/net/ibmveth.c b/drivers/net/ibmveth.c
index d2cc6d3f401..3515ef318eb 100644
--- a/drivers/net/ibmveth.c
+++ b/drivers/net/ibmveth.c
@@ -178,7 +178,7 @@ static void ibmveth_init_buffer_pool(struct ibmveth_buff_pool *pool, u32 pool_in
 	pool->size = pool_size;
 	pool->index = pool_index;
 	pool->buff_size = buff_size;
-	pool->threshold = pool_size / 2;
+	pool->threshold = pool_size * 7 / 8;
 	pool->active = pool_active;
 }
 
@@ -315,10 +315,13 @@ static void ibmveth_replenish_task(struct ibmveth_adapter *adapter)
 
 	adapter->replenish_task_cycles++;
 
-	for (i = (IbmVethNumBufferPools - 1); i >= 0; i--)
-		if(adapter->rx_buff_pool[i].active)
-			ibmveth_replenish_buffer_pool(adapter,
-						     &adapter->rx_buff_pool[i]);
+	for (i = (IbmVethNumBufferPools - 1); i >= 0; i--) {
+		struct ibmveth_buff_pool *pool = &adapter->rx_buff_pool[i];
+
+		if (pool->active &&
+		    (atomic_read(&pool->available) < pool->threshold))
+			ibmveth_replenish_buffer_pool(adapter, pool);
+	}
 
 	adapter->rx_no_buffer = *(u64*)(((char*)adapter->buffer_list_addr) + 4096 - 8);
 }