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Date: Tue, 14 Dec 2021 01:02:25 +0900
From: Vincent Mailhol <mailhol.vincent@...adoo.fr>
To: Marc Kleine-Budde <mkl@...gutronix.de>, linux-can@...r.kernel.org
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
Vincent Mailhol <mailhol.vincent@...adoo.fr>
Subject: [PATCH v6 3/4] can: dev: reorder struct can_priv members for better packing
Save eight bytes of holes on x86-64 architectures by reordering the
members of struct can_priv.
Before:
| $ pahole -C can_priv drivers/net/can/dev/dev.o
| struct can_priv {
| struct net_device * dev; /* 0 8 */
| struct can_device_stats can_stats; /* 8 24 */
| const struct can_bittiming_const * bittiming_const; /* 32 8 */
| const struct can_bittiming_const * data_bittiming_const; /* 40 8 */
| struct can_bittiming bittiming; /* 48 32 */
| /* --- cacheline 1 boundary (64 bytes) was 16 bytes ago --- */
| struct can_bittiming data_bittiming; /* 80 32 */
| const struct can_tdc_const * tdc_const; /* 112 8 */
| struct can_tdc tdc; /* 120 12 */
| /* --- cacheline 2 boundary (128 bytes) was 4 bytes ago --- */
| unsigned int bitrate_const_cnt; /* 132 4 */
| const u32 * bitrate_const; /* 136 8 */
| const u32 * data_bitrate_const; /* 144 8 */
| unsigned int data_bitrate_const_cnt; /* 152 4 */
| u32 bitrate_max; /* 156 4 */
| struct can_clock clock; /* 160 4 */
| unsigned int termination_const_cnt; /* 164 4 */
| const u16 * termination_const; /* 168 8 */
| u16 termination; /* 176 2 */
|
| /* XXX 6 bytes hole, try to pack */
|
| struct gpio_desc * termination_gpio; /* 184 8 */
| /* --- cacheline 3 boundary (192 bytes) --- */
| u16 termination_gpio_ohms[2]; /* 192 4 */
| enum can_state state; /* 196 4 */
| u32 ctrlmode; /* 200 4 */
| u32 ctrlmode_supported; /* 204 4 */
| int restart_ms; /* 208 4 */
|
| /* XXX 4 bytes hole, try to pack */
|
| struct delayed_work restart_work; /* 216 88 */
|
| /* XXX last struct has 4 bytes of padding */
|
| /* --- cacheline 4 boundary (256 bytes) was 48 bytes ago --- */
| int (*do_set_bittiming)(struct net_device *); /* 304 8 */
| int (*do_set_data_bittiming)(struct net_device *); /* 312 8 */
| /* --- cacheline 5 boundary (320 bytes) --- */
| int (*do_set_mode)(struct net_device *, enum can_mode); /* 320 8 */
| int (*do_set_termination)(struct net_device *, u16); /* 328 8 */
| int (*do_get_state)(const struct net_device *, enum can_state *); /* 336 8 */
| int (*do_get_berr_counter)(const struct net_device *, struct can_berr_counter *); /* 344 8 */
| unsigned int echo_skb_max; /* 352 4 */
|
| /* XXX 4 bytes hole, try to pack */
|
| struct sk_buff * * echo_skb; /* 360 8 */
|
| /* size: 368, cachelines: 6, members: 32 */
| /* sum members: 354, holes: 3, sum holes: 14 */
| /* paddings: 1, sum paddings: 4 */
| /* last cacheline: 48 bytes */
| };
After:
| $ pahole -C can_priv drivers/net/can/dev/dev.o
| struct can_priv {
| struct net_device * dev; /* 0 8 */
| struct can_device_stats can_stats; /* 8 24 */
| const struct can_bittiming_const * bittiming_const; /* 32 8 */
| const struct can_bittiming_const * data_bittiming_const; /* 40 8 */
| struct can_bittiming bittiming; /* 48 32 */
| /* --- cacheline 1 boundary (64 bytes) was 16 bytes ago --- */
| struct can_bittiming data_bittiming; /* 80 32 */
| const struct can_tdc_const * tdc_const; /* 112 8 */
| struct can_tdc tdc; /* 120 12 */
| /* --- cacheline 2 boundary (128 bytes) was 4 bytes ago --- */
| unsigned int bitrate_const_cnt; /* 132 4 */
| const u32 * bitrate_const; /* 136 8 */
| const u32 * data_bitrate_const; /* 144 8 */
| unsigned int data_bitrate_const_cnt; /* 152 4 */
| u32 bitrate_max; /* 156 4 */
| struct can_clock clock; /* 160 4 */
| unsigned int termination_const_cnt; /* 164 4 */
| const u16 * termination_const; /* 168 8 */
| u16 termination; /* 176 2 */
|
| /* XXX 6 bytes hole, try to pack */
|
| struct gpio_desc * termination_gpio; /* 184 8 */
| /* --- cacheline 3 boundary (192 bytes) --- */
| u16 termination_gpio_ohms[2]; /* 192 4 */
| unsigned int echo_skb_max; /* 196 4 */
| struct sk_buff * * echo_skb; /* 200 8 */
| enum can_state state; /* 208 4 */
| u32 ctrlmode; /* 212 4 */
| u32 ctrlmode_supported; /* 216 4 */
| int restart_ms; /* 220 4 */
| struct delayed_work restart_work; /* 224 88 */
|
| /* XXX last struct has 4 bytes of padding */
|
| /* --- cacheline 4 boundary (256 bytes) was 56 bytes ago --- */
| int (*do_set_bittiming)(struct net_device *); /* 312 8 */
| /* --- cacheline 5 boundary (320 bytes) --- */
| int (*do_set_data_bittiming)(struct net_device *); /* 320 8 */
| int (*do_set_mode)(struct net_device *, enum can_mode); /* 328 8 */
| int (*do_set_termination)(struct net_device *, u16); /* 336 8 */
| int (*do_get_state)(const struct net_device *, enum can_state *); /* 344 8 */
| int (*do_get_berr_counter)(const struct net_device *, struct can_berr_counter *); /* 352 8 */
|
| /* size: 360, cachelines: 6, members: 32 */
| /* sum members: 354, holes: 1, sum holes: 6 */
| /* paddings: 1, sum paddings: 4 */
| /* last cacheline: 40 bytes */
| };
Signed-off-by: Vincent Mailhol <mailhol.vincent@...adoo.fr>
---
include/linux/can/dev.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/include/linux/can/dev.h b/include/linux/can/dev.h
index fff3f70df697..c2ea47f30046 100644
--- a/include/linux/can/dev.h
+++ b/include/linux/can/dev.h
@@ -64,6 +64,9 @@ struct can_priv {
struct gpio_desc *termination_gpio;
u16 termination_gpio_ohms[CAN_TERMINATION_GPIO_MAX];
+ unsigned int echo_skb_max;
+ struct sk_buff **echo_skb;
+
enum can_state state;
/* CAN controller features - see include/uapi/linux/can/netlink.h */
@@ -83,9 +86,6 @@ struct can_priv {
struct can_berr_counter *bec);
int (*do_get_auto_tdcv)(const struct net_device *dev, u32 *tdcv);
- unsigned int echo_skb_max;
- struct sk_buff **echo_skb;
-
#ifdef CONFIG_CAN_LEDS
struct led_trigger *tx_led_trig;
char tx_led_trig_name[CAN_LED_NAME_SZ];
--
2.32.0
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