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723e1e8b77
The vma_munmap_struct has a hole of 4 bytes and pushes the struct to three
cachelines. Relocating the three booleans upwards allows for the struct
to only use two cachelines (as reported by pahole on amd64).
Before:
struct vma_munmap_struct {
struct vma_iterator * vmi; /* 0 8 */
struct vm_area_struct * vma; /* 8 8 */
struct vm_area_struct * prev; /* 16 8 */
struct vm_area_struct * next; /* 24 8 */
struct list_head * uf; /* 32 8 */
long unsigned int start; /* 40 8 */
long unsigned int end; /* 48 8 */
long unsigned int unmap_start; /* 56 8 */
/* --- cacheline 1 boundary (64 bytes) --- */
long unsigned int unmap_end; /* 64 8 */
int vma_count; /* 72 4 */
/* XXX 4 bytes hole, try to pack */
long unsigned int nr_pages; /* 80 8 */
long unsigned int locked_vm; /* 88 8 */
long unsigned int nr_accounted; /* 96 8 */
long unsigned int exec_vm; /* 104 8 */
long unsigned int stack_vm; /* 112 8 */
long unsigned int data_vm; /* 120 8 */
/* --- cacheline 2 boundary (128 bytes) --- */
bool unlock; /* 128 1 */
bool clear_ptes; /* 129 1 */
bool closed_vm_ops; /* 130 1 */
/* size: 136, cachelines: 3, members: 19 */
/* sum members: 127, holes: 1, sum holes: 4 */
/* padding: 5 */
/* last cacheline: 8 bytes */
};
After:
struct vma_munmap_struct {
struct vma_iterator * vmi; /* 0 8 */
struct vm_area_struct * vma; /* 8 8 */
struct vm_area_struct * prev; /* 16 8 */
struct vm_area_struct * next; /* 24 8 */
struct list_head * uf; /* 32 8 */
long unsigned int start; /* 40 8 */
long unsigned int end; /* 48 8 */
long unsigned int unmap_start; /* 56 8 */
/* --- cacheline 1 boundary (64 bytes) --- */
long unsigned int unmap_end; /* 64 8 */
int vma_count; /* 72 4 */
bool unlock; /* 76 1 */
bool clear_ptes; /* 77 1 */
bool closed_vm_ops; /* 78 1 */
/* XXX 1 byte hole, try to pack */
long unsigned int nr_pages; /* 80 8 */
long unsigned int locked_vm; /* 88 8 */
long unsigned int nr_accounted; /* 96 8 */
long unsigned int exec_vm; /* 104 8 */
long unsigned int stack_vm; /* 112 8 */
long unsigned int data_vm; /* 120 8 */
/* size: 128, cachelines: 2, members: 19 */
/* sum members: 127, holes: 1, sum holes: 1 */
};
Link: https://lkml.kernel.org/r/20240830040101.822209-22-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Bert Karwatzki <spasswolf@web.de>
Cc: Jeff Xu <jeffxu@chromium.org>
Cc: Jiri Olsa <olsajiri@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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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 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.