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mm/vma.h: optimise vma_munmap_struct

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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>
This commit is contained in:
Liam R. Howlett 2024-08-30 00:01:01 -04:00 committed by Andrew Morton
parent 20831cd6f8
commit 723e1e8b77
1 changed files with 4 additions and 3 deletions
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7
mm/vma.h
View file

@ -40,15 +40,16 @@ struct vma_munmap_struct {
unsigned long unmap_start; /* Unmap PTE start */
unsigned long unmap_end; /* Unmap PTE end */
int vma_count; /* Number of vmas that will be removed */
bool unlock; /* Unlock after the munmap */
bool clear_ptes; /* If there are outstanding PTE to be cleared */
bool closed_vm_ops; /* call_mmap() was encountered, so vmas may be closed */
/* 1 byte hole */
unsigned long nr_pages; /* Number of pages being removed */
unsigned long locked_vm; /* Number of locked pages */
unsigned long nr_accounted; /* Number of VM_ACCOUNT pages */
unsigned long exec_vm;
unsigned long stack_vm;
unsigned long data_vm;
bool unlock; /* Unlock after the munmap */
bool clear_ptes; /* If there are outstanding PTE to be cleared */
bool closed_vm_ops; /* call_mmap() was encountered, so vmas may be closed */
};
#ifdef CONFIG_DEBUG_VM_MAPLE_TREE