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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2013-07-23 22:11:42 +0200
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2013-08-29 13:20:11 +0200
commit0944fe3f4a323f436180d39402cae7f9c46ead17 (patch)
tree7b2ada69ff7e3c1fae20ec0b1dffe5e0d0ec2cc6 /mm
parentfbd70035fb2b03deb346052084794bc1d0e25aa2 (diff)
downloadlinux-0944fe3f4a323f436180d39402cae7f9c46ead17.tar.bz2
s390/mm: implement software referenced bits
The last remaining use for the storage key of the s390 architecture is reference counting. The alternative is to make page table entries invalid while they are old. On access the fault handler marks the pte/pmd as young which makes the pte/pmd valid if the access rights allow read access. The pte/pmd invalidations required for software managed reference bits cost a bit of performance, on the other hand the RRBE/RRBM instructions to read and reset the referenced bits are quite expensive as well. Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'mm')
-rw-r--r--mm/rmap.c3
1 files changed, 0 insertions, 3 deletions
diff --git a/mm/rmap.c b/mm/rmap.c
index b2e29acd7e3d..07748e68b729 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -873,9 +873,6 @@ int page_referenced(struct page *page,
vm_flags);
if (we_locked)
unlock_page(page);
-
- if (page_test_and_clear_young(page_to_pfn(page)))
- referenced++;
}
out:
return referenced;