This is a note to let you know that I've just added the patch titled
arm64: readahead: fault retry breaks mmap file read random detection
to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm64-readahead-fault-retry-breaks-mmap-file-read-random-detection.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 569ba74a7ba69f46ce2950bf085b37fea2408385 Mon Sep 17 00:00:00 2001
From: Mark Salyzyn <salyzyn@xxxxxxxxxxx>
Date: Mon, 21 Sep 2015 21:39:50 +0100
Subject: arm64: readahead: fault retry breaks mmap file read random detection
From: Mark Salyzyn <salyzyn@xxxxxxxxxxx>
commit 569ba74a7ba69f46ce2950bf085b37fea2408385 upstream.
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@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Wu Fengguang <fengguang.wu@xxxxxxxxx>
Signed-off-by: Mark Salyzyn <salyzyn@xxxxxxxxxxx>
Signed-off-by: Riley Andrews <riandrews@xxxxxxxxxxx>
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/mm/fault.c | 1 +
1 file changed, 1 insertion(+)
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -278,6 +278,7 @@ retry:
* starvation.
*/
mm_flags &= ~FAULT_FLAG_ALLOW_RETRY;
+ mm_flags |= FAULT_FLAG_TRIED;
goto retry;
}
}
Patches currently in stable-queue which might be from salyzyn@xxxxxxxxxxx are
queue-3.14/arm64-readahead-fault-retry-breaks-mmap-file-read-random-detection.patch
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