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 <[email protected]>
Signed-off-by: Shannon Nelson <[email protected]>
Acked-by: Jeff Kirsher <[email protected]>
Signed-off-by: Dan Williams <[email protected]>

diff --git a/drivers/dma/ioatdma.h b/drivers/dma/ioatdma.h
index a3306d0e1372a44b2950bc06d220d9b716f0bb00..dcf8db513c3a93af577ceec35f468d43c73c3a78 100644 (file)
--- 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
 }