path: root/arch
diff options
authorMark Salyzyn <salyzyn@android.com>2015-09-21 21:39:50 +0100
committerWill Deacon <will.deacon@arm.com>2015-10-05 16:30:50 +0100
commit569ba74a7ba69f46ce2950bf085b37fea2408385 (patch)
tree3a5ce66c7a3f903c9ce4927e8da4e187e3fb3870 /arch
parent95485fdc64b1067e0e88d8c7980eb57994ad450e (diff)
arm64: readahead: fault retry breaks mmap file read random detection
This is the arm64 portion of commit 45cac65b0fcd ("readahead: fault retry breaks mmap file read random detection"), which was absent from the initial port and has since gone unnoticed. The original commit says: > .fault now can retry. The retry can break state machine of .fault. In > filemap_fault, if page is miss, ra->mmap_miss is increased. In the second > try, since the page is in page cache now, ra->mmap_miss is decreased. And > these are done in one fault, so we can't detect random mmap file access. > > Add a new flag to indicate .fault is tried once. In the second try, skip > ra->mmap_miss decreasing. The filemap_fault state machine is ok with it. With this change, Mark reports that: > Random read improves by 250%, sequential read improves by 40%, and > random write by 400% to an eMMC device with dm crypto wrapped around it. Cc: Shaohua Li <shli@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Mark Salyzyn <salyzyn@android.com> Signed-off-by: Riley Andrews <riandrews@android.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch')
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index aba9ead1384c..9fadf6d7039b 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -287,6 +287,7 @@ retry:
* starvation.
+ mm_flags |= FAULT_FLAG_TRIED;
goto retry;