kernel: tune e1000e module parameters

The default e1000e parameters (interrupt throttling rate, MSI/MSI-X
mode) are optimized for desktop and server computers to optimize
user-space execution (i.e. what's typically referred to as "useful"
work).  This assumption breaks on a router under load where most of
the "useful" work actually takes place either in hardware interrupt
handlers (IRQ) or at software IRQ (swirq) modes, so we try to reflect
that by overriding these parameters with more appropriate values.

Patch-by: Philip Prindeville <[email protected]>
Signed-off-by: Jo-Philipp Wich <[email protected]>

package/kernel/linux/modules/netdevices.mk

@@ -488,6 +488,9 @@ define KernelPackage/e1000e
   KCONFIG:=CONFIG_E1000E
   FILES:=$(LINUX_DIR)/drivers/net/ethernet/intel/e1000e/e1000e.ko
   AUTOLOAD:=$(call AutoProbe,e1000e)
+  MODPARAMS.e1000e:= \
+    IntMode=1 \
+    InterruptThrottleRate=4,4,4,4,4,4,4,4
 endef
 
 define KernelPackage/e1000e/description