The patch titled
oom: document obsolete oom_adj tunable
has been added to the -mm tree. Its filename is
oom-document-obsolete-oom_adj-tunable.patch
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Subject: oom: document obsolete oom_adj tunable
From: David Rientjes <rientjes@xxxxxxxxxx>
/proc/pid/oom_adj was deprecated in August 2010 with the introduction of
the new oom killer heuristic.
This patch copies the Documentation/feature-removal-schedule.txt entry for
this tunable to the Documentation/ABI/obsolete directory so nobody misses
it.
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
Reported-by: Alan Cox <alan@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/ABI/obsolete/proc-pid-oom_adj | 22 ++++++++++++++++++
1 file changed, 22 insertions(+)
diff -puN /dev/null Documentation/ABI/obsolete/proc-pid-oom_adj
--- /dev/null
+++ a/Documentation/ABI/obsolete/proc-pid-oom_adj
@@ -0,0 +1,22 @@
+What: /proc/<pid>/oom_adj
+When: August 2012
+Why: /proc/<pid>/oom_adj allows userspace to influence the oom killer's
+ badness heuristic used to determine which task to kill when the kernel
+ is out of memory.
+
+ The badness heuristic has since been rewritten since the introduction of
+ this tunable such that its meaning is deprecated. The value was
+ implemented as a bitshift on a score generated by the badness()
+ function that did not have any precise units of measure. With the
+ rewrite, the score is given as a proportion of available memory to the
+ task allocating pages, so using a bitshift which grows the score
+ exponentially is, thus, impossible to tune with fine granularity.
+
+ A much more powerful interface, /proc/<pid>/oom_score_adj, was
+ introduced with the oom killer rewrite that allows users to increase or
+ decrease the badness() score linearly. This interface will replace
+ /proc/<pid>/oom_adj.
+
+ A warning will be emitted to the kernel log if an application uses this
+ deprecated interface. After it is printed once, future warnings will be
+ suppressed until the kernel is rebooted.
_
Patches currently in -mm which might be from rientjes@xxxxxxxxxx are
linux-next.patch
oom-document-obsolete-oom_adj-tunable.patch
jbd-remove-dependency-on-__gfp_nofail.patch
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