Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 51b1bd2a authored by David Rientjes's avatar David Rientjes Committed by Linus Torvalds
Browse files

oom: deprecate oom_adj tunable 



/proc/pid/oom_adj is now deprecated so that that it may eventually be
removed.  The target date for removal is August 2012.

A warning will be printed to the kernel log if a task attempts to use this
interface.  Future warning will be suppressed until the kernel is rebooted
to prevent spamming the kernel log.

Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a63d83f4

Documentation/feature-removal-schedule.txt

+25 −0
Original line number Diff line number Diff line
@@ -151,6 +151,31 @@ Who: Eric Biederman <ebiederm@xmission.com> 


---------------------------



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.



---------------------------



What:	remove EXPORT_SYMBOL(kernel_thread)

When:	August 2006

Files:	arch/*/kernel/*_ksyms.c

Documentation/filesystems/proc.txt

+3 −0
Original line number Diff line number Diff line
@@ -1285,6 +1285,9 @@ scaled linearly with /proc/<pid>/oom_score_adj. 
Writing to /proc/<pid>/oom_score_adj or /proc/<pid>/oom_adj will change the

other with its scaled value.



NOTICE: /proc/<pid>/oom_adj is deprecated and will be removed, please see

Documentation/feature-removal-schedule.txt.



Caveat: when a parent task is selected, the oom killer will sacrifice any first

generation children with seperate address spaces instead, if possible.  This

avoids servers and important system daemons from being killed and loses the

fs/proc/base.c

+8 −0
Original line number Diff line number Diff line
@@ -1037,6 +1037,14 @@ static ssize_t oom_adjust_write(struct file *file, const char __user *buf, 
		return -EACCES;

	}



	/*

	 * Warn that /proc/pid/oom_adj is deprecated, see

	 * Documentation/feature-removal-schedule.txt.

	 */

	printk_once(KERN_WARNING "%s (%d): /proc/%d/oom_adj is deprecated, "

			"please use /proc/%d/oom_score_adj instead.\n",

			current->comm, task_pid_nr(current),

			task_pid_nr(task), task_pid_nr(task));

	task->signal->oom_adj = oom_adjust;

	/*

	 * Scale /proc/pid/oom_score_adj appropriately ensuring that a maximum

include/linux/oom.h

+3 −0
Original line number Diff line number Diff line
@@ -2,6 +2,9 @@ 
#define __INCLUDE_LINUX_OOM_H



/*

 * /proc/<pid>/oom_adj is deprecated, see

 * Documentation/feature-removal-schedule.txt.

 *

 * /proc/<pid>/oom_adj set to -17 protects from the oom-killer

 */

#define OOM_DISABLE (-17)