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https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-04-19 05:02:37 -04:00
5fe1be81ef
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 */
| };
Link: https://lore.kernel.org/all/20211213160226.56219-4-mailhol.vincent@wanadoo.fr
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.