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a146cfaaa0
struct raw_sock has several holes. Reorder the fields to save 8 bytes.
Statistics before:
$ pahole --class_name=raw_sock net/can/raw.o
struct raw_sock {
struct sock sk __attribute__((__aligned__(8))); /* 0 776 */
/* XXX last struct has 1 bit hole */
/* --- cacheline 12 boundary (768 bytes) was 8 bytes ago --- */
int ifindex; /* 776 4 */
/* XXX 4 bytes hole, try to pack */
struct net_device * dev; /* 784 8 */
netdevice_tracker dev_tracker; /* 792 0 */
struct list_head notifier; /* 792 16 */
unsigned int bound:1; /* 808: 0 4 */
unsigned int loopback:1; /* 808: 1 4 */
unsigned int recv_own_msgs:1; /* 808: 2 4 */
unsigned int fd_frames:1; /* 808: 3 4 */
unsigned int xl_frames:1; /* 808: 4 4 */
unsigned int join_filters:1; /* 808: 5 4 */
/* XXX 2 bits hole, try to pack */
/* Bitfield combined with next fields */
struct can_raw_vcid_options raw_vcid_opts; /* 809 4 */
/* XXX 3 bytes hole, try to pack */
canid_t tx_vcid_shifted; /* 816 4 */
canid_t rx_vcid_shifted; /* 820 4 */
canid_t rx_vcid_mask_shifted; /* 824 4 */
int count; /* 828 4 */
/* --- cacheline 13 boundary (832 bytes) --- */
struct can_filter dfilter; /* 832 8 */
struct can_filter * filter; /* 840 8 */
can_err_mask_t err_mask; /* 848 4 */
/* XXX 4 bytes hole, try to pack */
struct uniqframe * uniq; /* 856 8 */
/* size: 864, cachelines: 14, members: 20 */
/* sum members: 852, holes: 3, sum holes: 11 */
/* sum bitfield members: 6 bits, bit holes: 1, sum bit holes: 2 bits */
/* member types with bit holes: 1, total: 1 */
/* forced alignments: 1 */
/* last cacheline: 32 bytes */
} __attribute__((__aligned__(8)));
...and after:
$ pahole --class_name=raw_sock net/can/raw.o
struct raw_sock {
struct sock sk __attribute__((__aligned__(8))); /* 0 776 */
/* XXX last struct has 1 bit hole */
/* --- cacheline 12 boundary (768 bytes) was 8 bytes ago --- */
struct net_device * dev; /* 776 8 */
netdevice_tracker dev_tracker; /* 784 0 */
struct list_head notifier; /* 784 16 */
int ifindex; /* 800 4 */
unsigned int bound:1; /* 804: 0 4 */
unsigned int loopback:1; /* 804: 1 4 */
unsigned int recv_own_msgs:1; /* 804: 2 4 */
unsigned int fd_frames:1; /* 804: 3 4 */
unsigned int xl_frames:1; /* 804: 4 4 */
unsigned int join_filters:1; /* 804: 5 4 */
/* XXX 2 bits hole, try to pack */
/* Bitfield combined with next fields */
struct can_raw_vcid_options raw_vcid_opts; /* 805 4 */
/* XXX 3 bytes hole, try to pack */
canid_t tx_vcid_shifted; /* 812 4 */
canid_t rx_vcid_shifted; /* 816 4 */
canid_t rx_vcid_mask_shifted; /* 820 4 */
can_err_mask_t err_mask; /* 824 4 */
int count; /* 828 4 */
/* --- cacheline 13 boundary (832 bytes) --- */
struct can_filter dfilter; /* 832 8 */
struct can_filter * filter; /* 840 8 */
struct uniqframe * uniq; /* 848 8 */
/* size: 856, cachelines: 14, members: 20 */
/* sum members: 852, holes: 1, sum holes: 3 */
/* sum bitfield members: 6 bits, bit holes: 1, sum bit holes: 2 bits */
/* member types with bit holes: 1, total: 1 */
/* forced alignments: 1 */
/* last cacheline: 24 bytes */
} __attribute__((__aligned__(8)));
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Vincent Mailhol <mailhol@kernel.org>
Link: https://patch.msgid.link/20250917-can-raw-repack-v2-3-395e8b3a4437@kernel.org
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 reStructuredText 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.