321f4992c1
We can reduce two members' size that in turn reduce size of struct
btrfs_ref from 64 to 56 bytes. As the structure is often used as a local
variable several functions reduce their stack usage.
- make enum btrfs_ref_type packed, there are only 4 values
- switch action and its values to a packed enum
Final structure layout:
struct btrfs_ref {
enum btrfs_ref_type type; /* 0 1 */
enum btrfs_delayed_ref_action action; /* 1 1 */
bool skip_qgroup; /* 2 1 */
/* XXX 5 bytes hole, try to pack */
u64 bytenr; /* 8 8 */
u64 len; /* 16 8 */
u64 parent; /* 24 8 */
union {
struct btrfs_data_ref data_ref; /* 32 24 */
struct btrfs_tree_ref tree_ref; /* 32 16 */
}; /* 32 24 */
/* size: 56, cachelines: 1, members: 7 */
/* sum members: 51, holes: 1, sum holes: 5 */
/* last cacheline: 56 bytes */
};
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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.