From: Rosen Penev <ros...@gmail.com>
Remove ____cacheline_aligned attribute to ring structs. This actually causes
holes in the ag71xx struct as well as lower performance.
Rearrange struct members to fall within respective cachelines. The RX ring
struct now does not share a cacheline with the TX ring. The NAPI struct now
takes up its own cachelines and does not share.
According to pahole -C ag71xx -c 32
Before:
struct ag71xx {
/* size: 384, cachelines: 12, members: 22 */
/* sum members: 375, holes: 2, sum holes: 9 */
After:
struct ag71xx {
/* size: 376, cachelines: 12, members: 22 */
/* last cacheline: 24 bytes */
Signed-off-by: Rosen Penev <ros...@gmail.com>
[Fix typos in the patch description]
Signed-off-by: Rui Salvaterra <rsalvate...@gmail.com>
---
The ag71xx_ring changes are already part of the upstream driver. However, since
we're not using it at all yet, let's apply this to our driver for the time
being, as David explicitly requests performance numbers before applying it
upstream [1] (and rightly so, in my opinion).
[1]
https://lore.kernel.org/netdev/20190725.112108.2287417619951369896.da...@davemloft.net/
.../net/ethernet/atheros/ag71xx/ag71xx.h | 32 ++++++++++---------
1 file changed, 17 insertions(+), 15 deletions(-)
diff --git
a/target/linux/ath79/files/drivers/net/ethernet/atheros/ag71xx/ag71xx.h
b/target/linux/ath79/files/drivers/net/ethernet/atheros/ag71xx/ag71xx.h
index 5ff9439f0d..6ed1f78459 100644
--- a/target/linux/ath79/files/drivers/net/ethernet/atheros/ag71xx/ag71xx.h
+++ b/target/linux/ath79/files/drivers/net/ethernet/atheros/ag71xx/ag71xx.h
@@ -107,13 +107,16 @@ struct ag71xx_buf {
};
struct ag71xx_ring {
- struct ag71xx_buf *buf;
- u8 *descs_cpu;
- dma_addr_t descs_dma;
- u16 desc_split;
- u16 order;
+ /* "Hot" fields in the data path. */
unsigned int curr;
unsigned int dirty;
+
+ /* "Cold" fields - not used in the data path. */
+ struct ag71xx_buf *buf;
+ u16 order;
+ u16 desc_split;
+ dma_addr_t descs_dma;
+ u8 *descs_cpu;
};
struct ag71xx_int_stats {
@@ -151,21 +154,20 @@ struct ag71xx {
* 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;
+ struct ag71xx_ring rx_ring;
+ u16 rx_buf_size;
+ u16 rx_buf_offset;
+ u32 msg_enable;
+ struct ag71xx_ring tx_ring;
int mac_idx;
-
u16 desc_pktlen_mask;
- u16 rx_buf_size;
- u8 rx_buf_offset;
u8 tx_hang_workaround:1;
+ struct napi_struct napi;
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.
@@ -188,12 +190,12 @@ struct ag71xx {
unsigned int speed;
int duplex;
- struct delayed_work restart_work;
- struct timer_list oom_timer;
-
struct reset_control *mac_reset;
struct reset_control *mdio_reset;
+ struct delayed_work restart_work;
+ struct timer_list oom_timer;
+
u32 fifodata[3];
u32 plldata[3];
u32 pllreg[3];
--
2.33.0
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