From e4c6bfd2d79d063017ab19a18915f0bc759f32d9 Mon Sep 17 00:00:00 2001 From: Rik van Riel Date: Tue, 11 Dec 2012 16:01:44 -0800 Subject: 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 Signed-off-by: Rik van Riel Cc: Hugh Dickins Cc: Russell King Cc: Ralf Baechle Cc: Paul Mundt Cc: "David S. Miller" Cc: Chris Metcalf Cc: Ingo Molnar Cc: Thomas Gleixner Cc: "H. Peter Anvin" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mm_types.h | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) (limited to 'include') diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 94fa52b28ee..7ade2731b5d 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 -- cgit v1.2.3