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authorThadeu Lima de Souza Cascardo <cascardo@linux.vnet.ibm.com>2012-07-16 07:01:53 +0000
committerDavid S. Miller <davem@davemloft.net>2012-07-19 10:53:13 -0700
commit4cce66cdd14aa5006a011505865d932adb49f600 (patch)
treecb6d4bed01679627b93b523f1fd0ba2dfbbc92c6 /drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
parenta9ec6bd1f7bccdc1304629f8fbb2e02035026307 (diff)
mlx4_en: map entire pages to increase throughput
In its receive path, mlx4_en driver maps each page chunk that it pushes to the hardware and unmaps it when pushing it up the stack. This limits throughput to about 3Gbps on a Power7 8-core machine. One solution is to map the entire allocated page at once. However, this requires that we keep track of every page fragment we give to a descriptor. We also need to work with the discipline that all fragments will be released (in the sense that it will not be reused by the driver anymore) in the order they are allocated to the driver. This requires that we don't reuse any fragments, every single one of them must be reallocated. We do that by releasing all the fragments that are processed and only after finished processing the descriptors, we start the refill. We also must somehow guarantee that we either refill all fragments in a descriptor or none at all, without resorting to giving up a page fragment that we would have already given. Otherwise, we would break the discipline of only releasing the fragments in the order they were allocated. This has passed page allocation fault injections (restricted to the driver by using required-start and required-end) and device hotplug while 16 TCP streams were able to deliver more than 9Gbps. Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@linux.vnet.ibm.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/ethernet/mellanox/mlx4/mlx4_en.h')
-rw-r--r--drivers/net/ethernet/mellanox/mlx4/mlx4_en.h3
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
index af34c98d43e5..5f1ab105debc 100644
--- a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
+++ b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
@@ -111,7 +111,7 @@ enum {
#define MLX4_EN_MAX_TX_SIZE 8192
#define MLX4_EN_MAX_RX_SIZE 8192
-/* Minimum ring size for our page-allocation sceme to work */
+/* Minimum ring size for our page-allocation scheme to work */
#define MLX4_EN_MIN_RX_SIZE (MLX4_EN_ALLOC_SIZE / SMP_CACHE_BYTES)
#define MLX4_EN_MIN_TX_SIZE (4096 / TXBB_SIZE)
@@ -232,6 +232,7 @@ struct mlx4_en_tx_desc {
struct mlx4_en_rx_alloc {
struct page *page;
+ dma_addr_t dma;
u16 offset;
};