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* sched: Mark autogroup_init() __initYong Zhang2011-01-071-1/+1
| | | | | | | | | | autogroup_init() is only called at boot time. Signed-off-by: Yong Zhang <yong.zhang0@gmail.com> Cc: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1294375425-31065-1-git-send-email-yong.zhang0@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Consolidate the name of root_task_group and init_task_groupYong Zhang2011-01-071-3/+3
| | | | | | | | | | | | | | | | | root_task_group is the leftover of USER_SCHED, now it's always same to init_task_group. But as Mike suggested, root_task_group is maybe the suitable name to keep for a tree. So in this patch: init_task_group --> root_task_group init_task_group_load --> root_task_group_load INIT_TASK_GROUP_LOAD --> ROOT_TASK_GROUP_LOAD Suggested-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Yong Zhang <yong.zhang0@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <20110107071736.GA32635@windriver.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched, autogroup: Fix potential access to freed memoryMike Galbraith2011-01-041-8/+17
| | | | | | | | | | | | | Oleg pointed out that the /proc interface kref_get() useage may race with the final put during autogroup_move_group(). A signal->autogroup assignment may be in flight when the /proc interface dereference, leaving them taking a reference to an already dead group. Reported-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1292508592.5940.28.camel@maggy.simson.net> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* sched: Add 'autogroup' scheduling feature: automated per session task groupsMike Galbraith2010-11-301-0/+229
A recurring complaint from CFS users is that parallel kbuild has a negative impact on desktop interactivity. This patch implements an idea from Linus, to automatically create task groups. Currently, only per session autogroups are implemented, but the patch leaves the way open for enhancement. Implementation: each task's signal struct contains an inherited pointer to a refcounted autogroup struct containing a task group pointer, the default for all tasks pointing to the init_task_group. When a task calls setsid(), a new task group is created, the process is moved into the new task group, and a reference to the preveious task group is dropped. Child processes inherit this task group thereafter, and increase it's refcount. When the last thread of a process exits, the process's reference is dropped, such that when the last process referencing an autogroup exits, the autogroup is destroyed. At runqueue selection time, IFF a task has no cgroup assignment, its current autogroup is used. Autogroup bandwidth is controllable via setting it's nice level through the proc filesystem: cat /proc/<pid>/autogroup Displays the task's group and the group's nice level. echo <nice level> > /proc/<pid>/autogroup Sets the task group's shares to the weight of nice <level> task. Setting nice level is rate limited for !admin users due to the abuse risk of task group locking. The feature is enabled from boot by default if CONFIG_SCHED_AUTOGROUP=y is selected, but can be disabled via the boot option noautogroup, and can also be turned on/off on the fly via: echo [01] > /proc/sys/kernel/sched_autogroup_enabled ... which will automatically move tasks to/from the root task group. Signed-off-by: Mike Galbraith <efault@gmx.de> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Markus Trippelsdorf <markus@trippelsdorf.de> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Paul Turner <pjt@google.com> Cc: Oleg Nesterov <oleg@redhat.com> [ Removed the task_group_path() debug code, and fixed !EVENTFD build failure. ] Signed-off-by: Ingo Molnar <mingo@elte.hu> LKML-Reference: <1290281700.28711.9.camel@maggy.simson.net> Signed-off-by: Ingo Molnar <mingo@elte.hu>