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| author | Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> | 2015-12-01 04:36:45 +0100 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2015-12-14 05:19:10 +0100 |
| commit | bf680d51605662aae5482d87e0e0a54ba6db056b (patch) | |
| tree | db17e9a9754e2f9fc10daa3bbb30ece19d21ba88 /init/do_mounts_md.c | |
| parent | powerpc/mm: Remove the dependency on pte bit position in asm code (diff) | |
| download | linux-bf680d51605662aae5482d87e0e0a54ba6db056b.tar.xz linux-bf680d51605662aae5482d87e0e0a54ba6db056b.zip | |
powerpc/mm: Don't track subpage valid bit in pte_t
This free up 11 bits in pte_t. In the later patch we also change
the pte_t format so that we can start supporting migration pte
at pmd level. We now track 4k subpage valid bit as below
If we have _PAGE_COMBO set, we override the _PAGE_F_GIX_SHIFT
and _PAGE_F_SECOND. Together we have 4 bits, each of them
used to indicate whether any of the 4 4k subpage in that group
is valid. ie,
[ group 1 bit ] [ group 2 bit ] ..... [ group 4 ]
[ subpage 1 - 4] [ subpage 5- 8] ..... [ subpage 13 - 16]
We still track each 4k subpage slot number and secondary hash
information in the second half of pgtable_t. Removing the subpage
tracking have some significant overhead on aim9 and ebizzy benchmark and
to support THP with 4K subpage, we do need a pgtable_t of 4096 bytes.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'init/do_mounts_md.c')
0 files changed, 0 insertions, 0 deletions