Merge tag 'v2.6.37' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6

[mv-sheeva.git] / Documentation / ABI / obsolete / proc-pid-oom_adj

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+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.