[dpdk-dev] [PATCH 1/4] igb_uio: add wc option

[Rafal Kozik <rk@semihalf.com>]

Write combining (wc) increase NIC performance by making better
utilization of PCI bus, but cannot be use by all PMD.

Parameter wc_activate add possibility to enable it for
those PMD that could support it.

Signed-off-by: Rafal Kozik <rk@semihalf.com>
---
 kernel/linux/igb_uio/igb_uio.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/kernel/linux/igb_uio/igb_uio.c b/kernel/linux/igb_uio/igb_uio.c
index 4cae4dd..42e3b3f 100644
--- a/kernel/linux/igb_uio/igb_uio.c
+++ b/kernel/linux/igb_uio/igb_uio.c
@@ -30,6 +30,7 @@ struct rte_uio_pci_dev {
 	int refcnt;
 };
 
+static int wc_activate;
 static char *intr_mode;
 static enum rte_intr_mode igbuio_intr_mode_preferred = RTE_INTR_MODE_MSIX;
 /* sriov sysfs */
@@ -375,9 +376,13 @@ igbuio_pci_setup_iomem(struct pci_dev *dev, struct uio_info *info,
 	len = pci_resource_len(dev, pci_bar);
 	if (addr == 0 || len == 0)
 		return -1;
-	internal_addr = ioremap(addr, len);
-	if (internal_addr == NULL)
-		return -1;
+	if (wc_activate == 0) {
+		internal_addr = ioremap(addr, len);
+		if (internal_addr == NULL)
+			return -1;
+	} else {
+		internal_addr = NULL;
+	}
 	info->mem[n].name = name;
 	info->mem[n].addr = addr;
 	info->mem[n].internal_addr = internal_addr;
@@ -638,6 +643,12 @@ MODULE_PARM_DESC(intr_mode,
 "    " RTE_INTR_MODE_LEGACY_NAME "     Use Legacy interrupt\n"
 "\n");
 
+module_param(wc_activate, int, 0);
+MODULE_PARM_DESC(wc_activate,
+"Activate support for write combining (WC) (default=0)\n"
+"    0 - disable\n"
+"    other - enable\n");
+
 MODULE_DESCRIPTION("UIO driver for Intel IGB PCI cards");
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Intel Corporation");
-- 
2.7.4