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SubjectRe: [PATCH v2 3/4] I/OAT: tcp_dma_copybreak default value dependant onI/OAT version
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On Fri, 2008-07-18 at 08:29 -0700, Sosnowski, Maciej wrote:
> I/OAT DMA performance tuning showed different optimal values
> of tcp_dma_copybreak for different I/OAT versions
> (4096 for 1.2 and 2048 for 2.0).
> This patch lets ioatdma driver set tcp_dma_copybreak value
> according to these results.
>
> Signed-off-by: Maciej Sosnowski <maciej.sosnowski@intel.com>

Let's kill some ifdef's... how about the following instead?

diff --git a/drivers/dma/ioat_dma.c b/drivers/dma/ioat_dma.c
index 171cad6..1c0dafc 100644
--- a/drivers/dma/ioat_dma.c
+++ b/drivers/dma/ioat_dma.c
@@ -1330,6 +1330,8 @@ struct ioatdma_device *ioat_dma_probe(struct pci_dev *pdev,
if (err)
goto err_self_test;

+ ioat_set_tcp_copy_break(device);
+
dma_async_device_register(&device->common);

return device;
diff --git a/drivers/dma/ioatdma.h b/drivers/dma/ioatdma.h
index f2c7fed..23e3196 100644
--- a/drivers/dma/ioatdma.h
+++ b/drivers/dma/ioatdma.h
@@ -27,6 +27,7 @@
#include <linux/dmapool.h>
#include <linux/cache.h>
#include <linux/pci_ids.h>
+#include <net/tcp.h>

#define IOAT_DMA_VERSION "2.04"

@@ -121,6 +122,20 @@ struct ioat_desc_sw {
struct dma_async_tx_descriptor async_tx;
};

+static inline void ioat_set_tcp_copy_break(struct ioatdma_device *dev)
+{
+ #ifdef CONFIG_NET_DMA
+ switch (dev->version) {
+ case IOAT_VER_1_2:
+ sysctl_tcp_dma_copybreak = 4096;
+ break;
+ case IOAT_VER_2_0:
+ sysctl_tcp_dma_copybreak = 2048;
+ break;
+ }
+ #endif
+}
+
#if defined(CONFIG_INTEL_IOATDMA) || defined(CONFIG_INTEL_IOATDMA_MODULE)
struct ioatdma_device *ioat_dma_probe(struct pci_dev *pdev,
void __iomem *iobase);
diff --git a/net/core/user_dma.c b/net/core/user_dma.c
index 0ad1cd5..de76050 100644
--- a/net/core/user_dma.c
+++ b/net/core/user_dma.c
@@ -34,6 +34,7 @@
#define NET_DMA_DEFAULT_COPYBREAK 4096

int sysctl_tcp_dma_copybreak = NET_DMA_DEFAULT_COPYBREAK;
+EXPORT_SYMBOL(sysctl_tcp_dma_copybreak);

/**
* dma_skb_copy_datagram_iovec - Copy a datagram to an iovec.



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