ag71xx: Reduce NAPI weight to 32.

Qualcomm claims this reduces cache misses. Original commit message below:

From: Ben Menchaca <ben.menchaca@qca.qualcomm.com>
Date: Tue, 11 Jun 2013 12:18:46 -0500
Subject: [ag71xx] reduce NAPI weight

In an attempt to increase our cache warmth, we are decreasing NAPI.
This increases the warmth of the reused SKBs.

Signed-off-by: Ben Menchaca <ben.menchaca@qca.qualcomm.com>
Signed-off-by: Rosen Penev <rosenp@gmail.com>

diff --git a/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx.h b/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx.h
index 898bde1d257bb70801f4f585c1aa278ebb9d0030..a7128129163e92a6cf789d2316a739758e5cf698 100644 (file)
--- a/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx.h
+++ b/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx.h
@@ -40,7 +40,12 @@
 #define AG71XX_DRV_NAME                "ag71xx"
 #define AG71XX_DRV_VERSION     "0.5.35"
 
 #define AG71XX_DRV_NAME                "ag71xx"
 #define AG71XX_DRV_VERSION     "0.5.35"
 

-#define AG71XX_NAPI_WEIGHT     64
+/*
+ * For our NAPI weight bigger does *NOT* mean better - it means more
+ * D-cache misses and lots more wasted cycles than we'll ever
+ * possibly gain from saving instructions.
+ */
+#define AG71XX_NAPI_WEIGHT     32

 #define AG71XX_OOM_REFILL      (1 + HZ/10)
 
 #define AG71XX_INT_ERR (AG71XX_INT_RX_BE | AG71XX_INT_TX_BE)
 #define AG71XX_OOM_REFILL      (1 + HZ/10)
 
 #define AG71XX_INT_ERR (AG71XX_INT_RX_BE | AG71XX_INT_TX_BE)