Commit 5de22343 authored Feb 26, 2009 by Maciej Sosnowski Committed by Dan Williams Mar 04, 2009

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>

parent 2b8a6bf8

drivers/dma/ioatdma.h

+3 −1

Original line number	Diff line number	Diff line
		@@ -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
		}

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