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Commit 50849d79 authored by Tom Herbert's avatar Tom Herbert Committed by David S. Miller
Browse files

e1000e: reduce writes of RX producer ptr 



Reduce number of writes to RX producer pointer.   When alloc'ing RX
buffers, only write the RX producer pointer once every
E1000_RX_BUFFER_WRITE (16) buffers created.

Signed-off-by: default avatarTom Herbert <therbert@google.com>
Acked-by: default avatarBruce Allan <bruce.w.allan@intel.com>
Signed-off-by: default avatarJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 9ed318d5

drivers/net/e1000e/netdev.c

+23 −34
Original line number Diff line number Diff line
@@ -548,17 +548,7 @@ map_skb: 
		rx_desc = E1000_RX_DESC(*rx_ring, i);

		rx_desc->buffer_addr = cpu_to_le64(buffer_info->dma);



		i++;

		if (i == rx_ring->count)

			i = 0;

		buffer_info = &rx_ring->buffer_info[i];

	}



	if (rx_ring->next_to_use != i) {

		rx_ring->next_to_use = i;

		if (i-- == 0)

			i = (rx_ring->count - 1);



		if (unlikely(!(i & (E1000_RX_BUFFER_WRITE - 1)))) {

			/*

			 * Force memory writes to complete before letting h/w

			 * know there are new descriptors to fetch.  (Only
@@ -568,6 +558,13 @@ map_skb: 
			wmb();

			writel(i, adapter->hw.hw_addr + rx_ring->tail);

		}

		i++;

		if (i == rx_ring->count)

			i = 0;

		buffer_info = &rx_ring->buffer_info[i];

	}



	rx_ring->next_to_use = i;

}



/**
@@ -649,19 +646,7 @@ static void e1000_alloc_rx_buffers_ps(struct e1000_adapter *adapter, 


		rx_desc->read.buffer_addr[0] = cpu_to_le64(buffer_info->dma);



		i++;

		if (i == rx_ring->count)

			i = 0;

		buffer_info = &rx_ring->buffer_info[i];

	}



no_buffers:

	if (rx_ring->next_to_use != i) {

		rx_ring->next_to_use = i;



		if (!(i--))

			i = (rx_ring->count - 1);



		if (unlikely(!(i & (E1000_RX_BUFFER_WRITE - 1)))) {

			/*

			 * Force memory writes to complete before letting h/w

			 * know there are new descriptors to fetch.  (Only
@@ -669,13 +654,17 @@ no_buffers: 
			 * such as IA-64).

			 */

			wmb();

		/*

		 * Hardware increments by 16 bytes, but packet split

		 * descriptors are 32 bytes...so we increment tail

		 * twice as much.

		 */

			writel(i<<1, adapter->hw.hw_addr + rx_ring->tail);

		}



		i++;

		if (i == rx_ring->count)

			i = 0;

		buffer_info = &rx_ring->buffer_info[i];

	}



no_buffers:

	rx_ring->next_to_use = i;

}



/**