mirror of
https://github.com/torvalds/linux.git
synced 2026-07-28 01:55:51 +02:00
Linux kernel source tree
890e5198a6
The bound, loopback, recv_own_msgs, fd_frames, xl_frames and
join_filters fields of struct raw_sock just need to store one bit of
information.
Declare all those members as a bitfields of type unsigned int and
width one bit.
Add a temporary variable to raw_setsockopt() and raw_getsockopt() to
make the conversion between the stored bits and the socket interface.
This reduces the size of struct raw_sock by sixteen 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 bound; /* 776 4 */
int ifindex; /* 780 4 */
struct net_device * dev; /* 784 8 */
netdevice_tracker dev_tracker; /* 792 0 */
struct list_head notifier; /* 792 16 */
int loopback; /* 808 4 */
int recv_own_msgs; /* 812 4 */
int fd_frames; /* 816 4 */
int xl_frames; /* 820 4 */
struct can_raw_vcid_options raw_vcid_opts; /* 824 4 */
canid_t tx_vcid_shifted; /* 828 4 */
/* --- cacheline 13 boundary (832 bytes) --- */
canid_t rx_vcid_shifted; /* 832 4 */
canid_t rx_vcid_mask_shifted; /* 836 4 */
int join_filters; /* 840 4 */
int count; /* 844 4 */
struct can_filter dfilter; /* 848 8 */
struct can_filter * filter; /* 856 8 */
can_err_mask_t err_mask; /* 864 4 */
/* XXX 4 bytes hole, try to pack */
struct uniqframe * uniq; /* 872 8 */
/* size: 880, cachelines: 14, members: 20 */
/* sum members: 876, holes: 1, sum holes: 4 */
/* member types with bit holes: 1, total: 1 */
/* forced alignments: 1 */
/* last cacheline: 48 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 --- */
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)));
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Vincent Mailhol <mailhol@kernel.org>
Link: https://patch.msgid.link/20250917-can-raw-repack-v2-2-395e8b3a4437@kernel.org
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .pylintrc | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.