Qualcomm claims this improves the D-cache footprint. Origina commit message
below:
From: Ben Menchaca <ben.mench...@qca.qualcomm.com>
Date: Fri, 7 Jun 2013 10:57:28 -0500
Subject: [ag71xx] cluster/align structs for cache perf
Cluster the frequently used, per-packet structures in ag71xx near
to each other, and cacheline-align them. Some other re-ordering
occurred to move "warmer" structures near the per-packet structures.
Signed-off-by: Ben Menchaca <ben.mench...@qca.qualcomm.com>
Signed-off-by: Rosen Penev <ros...@gmail.com>
---
.../drivers/net/ethernet/atheros/ag71xx/ag71xx.h | 27 ++++++++++++++--------
1 file changed, 17 insertions(+), 10 deletions(-)
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 a712812..5ead6b3 100644
--- a/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx.h
+++ b/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx.h
@@ -153,20 +153,31 @@ struct ag71xx_debug {
};
struct ag71xx {
- void __iomem *mac_base;
+ /*
+ * Critical data related to the per-packet data path are clustered
+ * early in this structure to help improve the D-cache footprint.
+ */
+ struct ag71xx_ring rx_ring ____cacheline_aligned;
+ struct ag71xx_ring tx_ring ____cacheline_aligned;
+
+ unsigned int max_frame_len;
+ unsigned int desc_pktlen_mask;
+ unsigned int rx_buf_size;
- spinlock_t lock;
- struct platform_device *pdev;
struct net_device *dev;
+ struct platform_device *pdev;
+ spinlock_t lock;
struct napi_struct napi;
u32 msg_enable;
+ /*
+ * From this point onwards we're not looking at per-packet fields.
+ */
+ void __iomem *mac_base;
+
struct ag71xx_desc *stop_desc;
dma_addr_t stop_desc_dma;
- struct ag71xx_ring rx_ring;
- struct ag71xx_ring tx_ring;
-
struct mii_bus *mii_bus;
struct phy_device *phy_dev;
void *phy_priv;
@@ -175,10 +186,6 @@ struct ag71xx {
unsigned int speed;
int duplex;
- unsigned int max_frame_len;
- unsigned int desc_pktlen_mask;
- unsigned int rx_buf_size;
-
struct delayed_work restart_work;
struct delayed_work link_work;
struct timer_list oom_timer;
--
2.7.4
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