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Linux kernel source tree
0625125877
Both dsa_port :: type and dsa_port :: index introduce a 4 octet hole
after them, so we can group them together and the holes would be
eliminated, turning 16 octets of storage into just 8. This makes the
cpu_dp pointer fit in the first cache line, which is good, because
dsa_slave_to_master(), called by dsa_enqueue_skb(), uses it.
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 */
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 */
};
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 */
struct dsa_switch * ds; /* 32 8 */
unsigned int index; /* 40 4 */
enum {
DSA_PORT_TYPE_UNUSED = 0,
DSA_PORT_TYPE_CPU = 1,
DSA_PORT_TYPE_DSA = 2,
DSA_PORT_TYPE_USER = 3,
} type; /* 44 4 */
const char * name; /* 48 8 */
struct dsa_port * cpu_dp; /* 56 8 */
/* --- cacheline 1 boundary (64 bytes) --- */
u8 mac[6]; /* 64 6 */
u8 stp_state; /* 70 1 */
u8 vlan_filtering:1; /* 71: 0 1 */
u8 learning:1; /* 71: 1 1 */
u8 lag_tx_enabled:1; /* 71: 2 1 */
u8 devlink_port_setup:1; /* 71: 3 1 */
u8 setup:1; /* 71: 4 1 */
/* XXX 3 bits hole, try to pack */
struct device_node * dn; /* 72 8 */
unsigned int ageing_time; /* 80 4 */
/* XXX 4 bytes hole, try to pack */
struct dsa_bridge * bridge; /* 88 8 */
struct devlink_port devlink_port; /* 96 288 */
/* --- cacheline 6 boundary (384 bytes) --- */
struct phylink * pl; /* 384 8 */
struct phylink_config pl_config; /* 392 40 */
struct net_device * lag_dev; /* 432 8 */
struct net_device * hsr_dev; /* 440 8 */
/* --- cacheline 7 boundary (448 bytes) --- */
struct list_head list; /* 448 16 */
const struct ethtool_ops * orig_ethtool_ops; /* 464 8 */
const struct dsa_netdevice_ops * netdev_ops; /* 472 8 */
struct mutex addr_lists_lock; /* 480 32 */
/* --- cacheline 8 boundary (512 bytes) --- */
struct list_head fdbs; /* 512 16 */
struct list_head mdbs; /* 528 16 */
/* size: 544, cachelines: 9, members: 30 */
/* sum members: 539, holes: 1, sum holes: 4 */
/* sum bitfield members: 5 bits, bit holes: 1, sum bit holes: 3 bits */
/* last cacheline: 32 bytes */
};
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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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.