I/OAT: set tcp_dma_copybreak to 256k for I/OAT ver.3

Upcoming server platforms from Intel based on the Nehalem performance
have significantly improved CPU based copy performance.
However, the DMA engine can still be effective at higher I/O sizes
for TCP traffic and at this time copybreak
should be set to 256k for TCP traffic only.

Signed-off-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: Shannon Nelson <shannon.nelson@intel.com>
Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/dma/ioatdma.h b/drivers/dma/ioatdma.h
index a3306d0e1372..dcf8db513c3a 100644
--- a/drivers/dma/ioatdma.h
+++ b/drivers/dma/ioatdma.h
@@ -135,12 +135,14 @@ static inline void ioat_set_tcp_copy_break(struct ioatdma_device *dev)
         #ifdef CONFIG_NET_DMA
         switch (dev->version) {
         case IOAT_VER_1_2:
-        case IOAT_VER_3_0:
                 sysctl_tcp_dma_copybreak = 4096;
                 break;
         case IOAT_VER_2_0:
                 sysctl_tcp_dma_copybreak = 2048;
                 break;
+        case IOAT_VER_3_0:
+                sysctl_tcp_dma_copybreak = 262144;
+                break;
         }
         #endif
 }