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authorChen, Kenneth W <kenneth.w.chen@intel.com>2006-12-06 20:32:03 -0800
committerLinus Torvalds <torvalds@woody.osdl.org>2006-12-07 08:39:21 -0800
commit39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa (patch)
tree750818d68ac7381f80fec31491e1d1c78df4b9f6 /arch/sparc64/mm
parente1dbeda60a7ea9e82a908d93c07308d104d50d79 (diff)
downloadlinux-2.6.34-ux500-39dde65c9940c97fcd178a3d2b1c57ed8b7b68aa.tar.gz
[PATCH] shared page table for hugetlb page
Following up with the work on shared page table done by Dave McCracken. This set of patch target shared page table for hugetlb memory only. The shared page table is particular useful in the situation of large number of independent processes sharing large shared memory segments. In the normal page case, the amount of memory saved from process' page table is quite significant. For hugetlb, the saving on page table memory is not the primary objective (as hugetlb itself already cuts down page table overhead significantly), instead, the purpose of using shared page table on hugetlb is to allow faster TLB refill and smaller cache pollution upon TLB miss. With PT sharing, pte entries are shared among hundreds of processes, the cache consumption used by all the page table is smaller and in return, application gets much higher cache hit ratio. One other effect is that cache hit ratio with hardware page walker hitting on pte in cache will be higher and this helps to reduce tlb miss latency. These two effects contribute to higher application performance. Signed-off-by: Ken Chen <kenneth.w.chen@intel.com> Acked-by: Hugh Dickins <hugh@veritas.com> Cc: Dave McCracken <dmccr@us.ibm.com> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Adam Litke <agl@us.ibm.com> Cc: Paul Mundt <lethal@linux-sh.org> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/sparc64/mm')
-rw-r--r--arch/sparc64/mm/hugetlbpage.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/sparc64/mm/hugetlbpage.c b/arch/sparc64/mm/hugetlbpage.c
index 53b9b1f528e..33fd0b265e7 100644
--- a/arch/sparc64/mm/hugetlbpage.c
+++ b/arch/sparc64/mm/hugetlbpage.c
@@ -235,6 +235,11 @@ pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
return pte;
}
+int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
+{
+ return 0;
+}
+
void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t entry)
{