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| author | Rik van Riel <riel@surriel.com> | 2012-12-11 16:01:44 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-12-11 17:22:25 -0800 |
| commit | e4c6bfd2d79d063017ab19a18915f0bc759f32d9 (patch) | |
| tree | 4f97a0303f939a7846a86c7ade2533a8e2712f29 | |
| parent | 5a0768f641a5bad844860e67250baf0d1aa5e03c (diff) | |
| download | linux-e4c6bfd2d79d063017ab19a18915f0bc759f32d9.tar.gz | |
mm: rearrange vm_area_struct for fewer cache misses
The kernel walks the VMA rbtree in various places, including the page fault path. However, the vm_rb node spanned two cache lines, on 64 bit systems with 64 byte cache lines (most x86 systems). Rearrange vm_area_struct a little, so all the information we need to do a VMA tree walk is in the first cache line. [akpm@linux-foundation.org: checkpatch fixes] Signed-off-by: Michel Lespinasse <walken@google.com> Signed-off-by: Rik van Riel <riel@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | include/linux/mm_types.h | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 94fa52b28ee8..7ade2731b5d6 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -224,7 +224,8 @@ struct vm_region { * library, the executable area etc). */ struct vm_area_struct { - struct mm_struct * vm_mm; /* The address space we belong to. */ + /* The first cache line has the info for VMA tree walking. */ + unsigned long vm_start; /* Our start address within vm_mm. */ unsigned long vm_end; /* The first byte after our end address within vm_mm. */ @@ -232,9 +233,6 @@ struct vm_area_struct { /* linked list of VM areas per task, sorted by address */ struct vm_area_struct *vm_next, *vm_prev; - pgprot_t vm_page_prot; /* Access permissions of this VMA. */ - unsigned long vm_flags; /* Flags, see mm.h. */ - struct rb_node vm_rb; /* @@ -245,6 +243,12 @@ struct vm_area_struct { */ unsigned long rb_subtree_gap; + /* Second cache line starts here. */ + + struct mm_struct *vm_mm; /* The address space we belong to. */ + pgprot_t vm_page_prot; /* Access permissions of this VMA. */ + unsigned long vm_flags; /* Flags, see mm.h. */ + /* * For areas with an address space and backing store, * linkage into the address_space->i_mmap interval tree, or |