mirror of
https://github.com/hardkernel/linux.git
synced 2026-06-03 09:41:54 +09:00
bde82f389a
struct dsa_port has 5 bool members which create quite a number of 7 byte
holes in the structure layout. By merging them all into bitfields of an
u8, and placing that u8 in the 1-byte hole after dp->mac and dp->stp_state,
we can reduce the structure size from 576 bytes to 552 bytes on arm64.
Before:
pahole -C dsa_port net/dsa/slave.o
struct dsa_port {
union {
struct net_device * master; /* 0 8 */
struct net_device * slave; /* 0 8 */
}; /* 0 8 */
const struct dsa_device_ops * tag_ops; /* 8 8 */
struct dsa_switch_tree * dst; /* 16 8 */
struct sk_buff * (*rcv)(struct sk_buff *, struct net_device *); /* 24 8 */
enum {
DSA_PORT_TYPE_UNUSED = 0,
DSA_PORT_TYPE_CPU = 1,
DSA_PORT_TYPE_DSA = 2,
DSA_PORT_TYPE_USER = 3,
} type; /* 32 4 */
/* XXX 4 bytes hole, try to pack */
struct dsa_switch * ds; /* 40 8 */
unsigned int index; /* 48 4 */
/* XXX 4 bytes hole, try to pack */
const char * name; /* 56 8 */
/* --- cacheline 1 boundary (64 bytes) --- */
struct dsa_port * cpu_dp; /* 64 8 */
u8 mac[6]; /* 72 6 */
u8 stp_state; /* 78 1 */
/* XXX 1 byte hole, try to pack */
struct device_node * dn; /* 80 8 */
unsigned int ageing_time; /* 88 4 */
bool vlan_filtering; /* 92 1 */
bool learning; /* 93 1 */
/* XXX 2 bytes hole, try to pack */
struct dsa_bridge * bridge; /* 96 8 */
struct devlink_port devlink_port; /* 104 288 */
/* --- cacheline 6 boundary (384 bytes) was 8 bytes ago --- */
bool devlink_port_setup; /* 392 1 */
/* XXX 7 bytes hole, try to pack */
struct phylink * pl; /* 400 8 */
struct phylink_config pl_config; /* 408 40 */
/* --- cacheline 7 boundary (448 bytes) --- */
struct net_device * lag_dev; /* 448 8 */
bool lag_tx_enabled; /* 456 1 */
/* XXX 7 bytes hole, try to pack */
struct net_device * hsr_dev; /* 464 8 */
struct list_head list; /* 472 16 */
const struct ethtool_ops * orig_ethtool_ops; /* 488 8 */
const struct dsa_netdevice_ops * netdev_ops; /* 496 8 */
struct mutex addr_lists_lock; /* 504 32 */
/* --- cacheline 8 boundary (512 bytes) was 24 bytes ago --- */
struct list_head fdbs; /* 536 16 */
struct list_head mdbs; /* 552 16 */
bool setup; /* 568 1 */
/* size: 576, cachelines: 9, members: 30 */
/* sum members: 544, holes: 6, sum holes: 25 */
/* padding: 7 */
};
After:
pahole -C dsa_port net/dsa/slave.o
struct dsa_port {
union {
struct net_device * master; /* 0 8 */
struct net_device * slave; /* 0 8 */
}; /* 0 8 */
const struct dsa_device_ops * tag_ops; /* 8 8 */
struct dsa_switch_tree * dst; /* 16 8 */
struct sk_buff * (*rcv)(struct sk_buff *, struct net_device *); /* 24 8 */
enum {
DSA_PORT_TYPE_UNUSED = 0,
DSA_PORT_TYPE_CPU = 1,
DSA_PORT_TYPE_DSA = 2,
DSA_PORT_TYPE_USER = 3,
} type; /* 32 4 */
/* XXX 4 bytes hole, try to pack */
struct dsa_switch * ds; /* 40 8 */
unsigned int index; /* 48 4 */
/* XXX 4 bytes hole, try to pack */
const char * name; /* 56 8 */
/* --- cacheline 1 boundary (64 bytes) --- */
struct dsa_port * cpu_dp; /* 64 8 */
u8 mac[6]; /* 72 6 */
u8 stp_state; /* 78 1 */
u8 vlan_filtering:1; /* 79: 0 1 */
u8 learning:1; /* 79: 1 1 */
u8 lag_tx_enabled:1; /* 79: 2 1 */
u8 devlink_port_setup:1; /* 79: 3 1 */
u8 setup:1; /* 79: 4 1 */
/* XXX 3 bits hole, try to pack */
struct device_node * dn; /* 80 8 */
unsigned int ageing_time; /* 88 4 */
/* XXX 4 bytes hole, try to pack */
struct dsa_bridge * bridge; /* 96 8 */
struct devlink_port devlink_port; /* 104 288 */
/* --- cacheline 6 boundary (384 bytes) was 8 bytes ago --- */
struct phylink * pl; /* 392 8 */
struct phylink_config pl_config; /* 400 40 */
struct net_device * lag_dev; /* 440 8 */
/* --- cacheline 7 boundary (448 bytes) --- */
struct net_device * hsr_dev; /* 448 8 */
struct list_head list; /* 456 16 */
const struct ethtool_ops * orig_ethtool_ops; /* 472 8 */
const struct dsa_netdevice_ops * netdev_ops; /* 480 8 */
struct mutex addr_lists_lock; /* 488 32 */
/* --- cacheline 8 boundary (512 bytes) was 8 bytes ago --- */
struct list_head fdbs; /* 520 16 */
struct list_head mdbs; /* 536 16 */
/* size: 552, cachelines: 9, members: 30 */
/* sum members: 539, holes: 3, sum holes: 12 */
/* sum bitfield members: 5 bits, bit holes: 1, sum bit holes: 3 bits */
/* last cacheline: 40 bytes */
};
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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.