Vladimir Oltean b035c88c6a net: dsa: move dsa_switch_tree :: ports and lags to first cache line
dst->ports is accessed most notably by dsa_master_find_slave(), which is
invoked in the RX path.

dst->lags is accessed by dsa_lag_dev(), which is invoked in the RX path
of tag_dsa.c.

dst->tag_ops, dst->default_proto and dst->pd don't need to be in the
first cache line, so they are moved out by this change.

Before:

pahole -C dsa_switch_tree net/dsa/slave.o
struct dsa_switch_tree {
        struct list_head           list;                 /*     0    16 */
        struct raw_notifier_head   nh;                   /*    16     8 */
        unsigned int               index;                /*    24     4 */
        struct kref                refcount;             /*    28     4 */
        bool                       setup;                /*    32     1 */

        /* XXX 7 bytes hole, try to pack */

        const struct dsa_device_ops  * tag_ops;          /*    40     8 */
        enum dsa_tag_protocol      default_proto;        /*    48     4 */

        /* XXX 4 bytes hole, try to pack */

        struct dsa_platform_data * pd;                   /*    56     8 */
        /* --- cacheline 1 boundary (64 bytes) --- */
        struct list_head           ports;                /*    64    16 */
        struct list_head           rtable;               /*    80    16 */
        struct net_device * *      lags;                 /*    96     8 */
        unsigned int               lags_len;             /*   104     4 */
        unsigned int               last_switch;          /*   108     4 */

        /* size: 112, cachelines: 2, members: 13 */
        /* sum members: 101, holes: 2, sum holes: 11 */
        /* last cacheline: 48 bytes */
};

After:

pahole -C dsa_switch_tree net/dsa/slave.o
struct dsa_switch_tree {
        struct list_head           list;                 /*     0    16 */
        struct list_head           ports;                /*    16    16 */
        struct raw_notifier_head   nh;                   /*    32     8 */
        unsigned int               index;                /*    40     4 */
        struct kref                refcount;             /*    44     4 */
        struct net_device * *      lags;                 /*    48     8 */
        bool                       setup;                /*    56     1 */

        /* XXX 7 bytes hole, try to pack */

        /* --- cacheline 1 boundary (64 bytes) --- */
        const struct dsa_device_ops  * tag_ops;          /*    64     8 */
        enum dsa_tag_protocol      default_proto;        /*    72     4 */

        /* XXX 4 bytes hole, try to pack */

        struct dsa_platform_data * pd;                   /*    80     8 */
        struct list_head           rtable;               /*    88    16 */
        unsigned int               lags_len;             /*   104     4 */
        unsigned int               last_switch;          /*   108     4 */

        /* size: 112, cachelines: 2, members: 13 */
        /* sum members: 101, holes: 2, sum holes: 11 */
        /* last cacheline: 48 bytes */
};

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-01-05 14:46:23 +00:00
2021-12-26 13:17:17 -08:00

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.
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