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2007-11-09sched: fix copy_namespace() <-> sched_fork() dependency in do_forkSrivatsa Vaddagiri
Sukadev Bhattiprolu reported a kernel crash with control groups. There are couple of problems discovered by Suka's test: - The test requires the cgroup filesystem to be mounted with atleast the cpu and ns options (i.e both namespace and cpu controllers are active in the same hierarchy). # mkdir /dev/cpuctl # mount -t cgroup -ocpu,ns none cpuctl (or simply) # mount -t cgroup none cpuctl -> Will activate all controllers in same hierarchy. - The test invokes clone() with CLONE_NEWNS set. This causes a a new child to be created, also a new group (do_fork->copy_namespaces->ns_cgroup_clone-> cgroup_clone) and the child is attached to the new group (cgroup_clone-> attach_task->sched_move_task). At this point in time, the child's scheduler related fields are uninitialized (including its on_rq field, which it has inherited from parent). As a result sched_move_task thinks its on runqueue, when it isn't. As a solution to this problem, I moved sched_fork() call, which initializes scheduler related fields on a new task, before copy_namespaces(). I am not sure though whether moving up will cause other side-effects. Do you see any issue? - The second problem exposed by this test is that task_new_fair() assumes that parent and child will be part of the same group (which needn't be as this test shows). As a result, cfs_rq->curr can be NULL for the child. The solution is to test for curr pointer being NULL in task_new_fair(). With the patch below, I could run ns_exec() fine w/o a crash. Reported-by: Sukadev Bhattiprolu <sukadev@us.ibm.com> Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-11-09sched: clean up the wakeup preempt check, #2Ingo Molnar
clean up the preemption check to not use unnecessary 64-bit variables. This improves code size: text data bss dec hex filename 44227 3326 36 47589 b9e5 sched.o.before 44201 3326 36 47563 b9cb sched.o.after Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-11-09sched: clean up the wakeup preempt checkIngo Molnar
clean up the wakeup preemption check. No code changed: text data bss dec hex filename 44227 3326 36 47589 b9e5 sched.o.before 44227 3326 36 47589 b9e5 sched.o.after Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-11-09sched: wakeup preemption fixIngo Molnar
wakeup preemption fix: do not make it dependent on p->prio. Preemption purely depends on ->vruntime. This improves preemption in mixed-nice-level workloads. Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-11-09sched: remove PREEMPT_RESTRICTIngo Molnar
remove PREEMPT_RESTRICT. (this is a separate commit so that any regression related to the removal itself is bisectable) Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-11-09sched: reintroduce SMP tunings againIngo Molnar
Yanmin Zhang reported an aim7 regression and bisected it down to: | commit 38ad464d410dadceda1563f36bdb0be7fe4c8938 | Author: Ingo Molnar <mingo@elte.hu> | Date: Mon Oct 15 17:00:02 2007 +0200 | | sched: uniform tunings | | use the same defaults on both UP and SMP. fix this by reintroducing similar SMP tunings again. This resolves the regression. (also update the comments to match the ilog2(nr_cpus) tuning effect) Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-11-09sched: reintroduce the sched_min_granularity tunablePeter Zijlstra
we lost the sched_min_granularity tunable to a clever optimization that uses the sched_latency/min_granularity ratio - but the ratio is quite unintuitive to users and can also crash the kernel if the ratio is set to 0. So reintroduce the min_granularity tunable, while keeping the ratio maintained internally. no functionality changed. [ mingo@elte.hu: some fixlets. ] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-11-09sched: documentation: place_entity() commentsPeter Zijlstra
Add a few comments to place_entity(). No code changed. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-11-09sched: fix vslicePeter Zijlstra
vslice was missing a factor NICE_0_LOAD, as weight is in weight*NICE_0_LOAD units. the effect of this bug was larger initial slices and thus latency-noisier forks. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-29sched: fix style of swap() macro in kernel/sched_fair.cIngo Molnar
fix style of swap() macro in kernel/sched_fair.c. ( this macro should eventually move to a general header, as ext3 uses a similar construct too. ) Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-24sched: isolate SMP balancing code a bit morePeter Williams
At the moment, a lot of load balancing code that is irrelevant to non SMP systems gets included during non SMP builds. This patch addresses this issue and reduces the binary size on non SMP systems: text data bss dec hex filename 10983 28 1192 12203 2fab sched.o.before 10739 28 1192 11959 2eb7 sched.o.after Signed-off-by: Peter Williams <pwil3058@bigpond.net.au> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-24sched: reduce balance-tasks overheadPeter Williams
At the moment, balance_tasks() provides low level functionality for both move_tasks() and move_one_task() (indirectly) via the load_balance() function (in the sched_class interface) which also provides dual functionality. This dual functionality complicates the interfaces and internal mechanisms and makes the run time overhead of operations that are called with two run queue locks held. This patch addresses this issue and reduces the overhead of these operations. Signed-off-by: Peter Williams <pwil3058@bigpond.net.au> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-17sched: fix new task startup crashSrivatsa Vaddagiri
Child task may be added on a different cpu that the one on which parent is running. In which case, task_new_fair() should check whether the new born task's parent entity should be added as well on the cfs_rq. Patch below fixes the problem in task_new_fair. This could fix the put_prev_task_fair() crashes reported. Reported-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Reported-by: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15sched: reintroduce cache-hot affinityIngo Molnar
reintroduce a simplified version of cache-hot/cold scheduling affinity. This improves performance with certain SMP workloads, such as sysbench. Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15sched: speed up context-switches a bitIngo Molnar
speed up context-switches a bit by not clearing p->exec_start. (as a side-effect, this also makes p->exec_start a universal timestamp available to cache-hot estimations.) Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15sched: do not wakeup-preempt with SCHED_BATCH tasksIngo Molnar
do not wakeup-preempt with SCHED_BATCH tasks, their preemption is batched too, driven by the tick. Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15sched: update commentIngo Molnar
update comment: clarify time-slices and remove obsolete tuning detail. Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15sched: prevent wakeup over-schedulingMike Galbraith
Prevent wakeup over-scheduling. Once a task has been preempted by a task of the same or lower priority, it becomes ineligible for repeated preemption by same until it has been ticked, or slept. Instead, the task is marked for preemption at the next tick. Tasks of higher priority still preempt immediately. Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15sched: disable forced preemption by defaultPeter Zijlstra
Implement feature bit to disable forced preemption. This way it can be checked whether a workload is overscheduling or not. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15sched: fix group scheduling for SCHED_BATCHDmitry Adamushko
The following patch (sched: disable sleeper_fairness on SCHED_BATCH) seems to break GROUP_SCHED. Although, it may be 'oops'-less due to the possibility of 'p' being always a valid address. Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15sched: disable sleeper_fairness on SCHED_BATCHPeter Zijlstra
disable sleeper fairness for batch tasks - they are about batch processing after all. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15sched: another wakeup_granularity fixPeter Zijlstra
unit mis-match: wakeup_gran was used against a vruntime Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15sched: fix: move the CPU check into ->task_new_fair()Ingo Molnar
noticed by Peter Zijlstra: fix: move the CPU check into ->task_new_fair(), this way we can call place_entity() and get child ->vruntime right at initial wakeup time. (without this there can be large latencies) Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-10-15sched: cleanup: function prototype cleanupsIngo Molnar
noticed by Thomas Gleixner: cleanup: function prototype cleanups - move into single line wherever possible. Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15sched: cleanup: rename SCHED_FEAT_USE_TREE_AVG to SCHED_FEAT_TREE_AVGIngo Molnar
cleanup: rename SCHED_FEAT_USE_TREE_AVG to SCHED_FEAT_TREE_AVG, to make SCHED_FEAT_ names more consistent. Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15sched: cleanup, make dequeue_entity() and update_stats_wait_end() similarDmitry Adamushko
make dequeue_entity() / enqueue_entity() and update_stats_dequeue() / update_stats_enqueue() look similar, structure-wise. zero effect, functionality-wise: text data bss dec hex filename 34550 3026 100 37676 932c sched.o.before 34550 3026 100 37676 932c sched.o.after Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15sched: cleanup, remove calc_weighted()Dmitry Adamushko
remove obsolete code -- calc_weighted() Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15sched: uninline schedulerAlexey Dobriyan
* save ~300 bytes * activate_idle_task() was moved to avoid a warning bloat-o-meter output: add/remove: 6/0 grow/shrink: 0/16 up/down: 438/-733 (-295) <=== function old new delta __enqueue_entity - 165 +165 finish_task_switch - 110 +110 update_curr_rt - 79 +79 __load_balance_iterator - 32 +32 __task_rq_unlock - 28 +28 find_process_by_pid - 24 +24 do_sched_setscheduler 133 123 -10 sys_sched_rr_get_interval 176 165 -11 sys_sched_getparam 156 145 -11 normalize_rt_tasks 482 470 -12 sched_getaffinity 112 99 -13 sys_sched_getscheduler 86 72 -14 sched_setaffinity 226 212 -14 sched_setscheduler 666 642 -24 load_balance_start_fair 33 9 -24 load_balance_next_fair 33 9 -24 dequeue_task_rt 133 67 -66 put_prev_task_rt 97 28 -69 schedule_tail 133 50 -83 schedule 682 594 -88 enqueue_entity 499 366 -133 task_new_fair 317 180 -137 Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15sched: tweak wakeup granularityIngo Molnar
tweak wakeup granularity. Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15sched: fix __pick_next_entity()Dmitry Adamushko
The thing is that __pick_next_entity() must never be called when first_fair(cfs_rq) == NULL. It wouldn't be a problem, should 'run_node' be the very first field of 'struct sched_entity' (and it's the second). The 'nr_running != 0' check is _not_ enough, due to the fact that 'current' is not within the tree. Generic paths are ok (e.g. schedule() as put_prev_task() is called previously)... I'm more worried about e.g. migration_call() -> CPU_DEAD_FROZEN -> migrate_dead_tasks()... if 'current' == rq->idle, no problems.. if it's one of the SCHED_NORMAL tasks (or imagine, some other use-cases in the future -- i.e. we should not make outer world dependent on internal details of sched_fair class) -- it may be "Houston, we've got a problem" case. it's +16 bytes to the ".text". Another variant is to make 'run_node' the first data member of 'struct sched_entity' but an additional check (se ! = NULL) is still needed in pick_next_entity(). Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15sched: vslice fixups for non-0 nice levelsIngo Molnar
Make vslice accurate wrt nice levels, and add some comments while we're at it. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15sched: mark scheduling classes as constIngo Molnar
mark scheduling classes as const. The speeds up the code a bit and shrinks it: text data bss dec hex filename 40027 4018 292 44337 ad31 sched.o.before 40190 3842 292 44324 ad24 sched.o.after Signed-off-by: Ingo Molnar <mingo@elte.hu> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15sched: group scheduler, fix latencySrivatsa Vaddagiri
There is a possibility that because of task of a group moving from one cpu to another, it may gain more cpu time that desired. See http://marc.info/?l=linux-kernel&m=119073197730334 for details. This is an attempt to fix that problem. Basically it simulates dequeue of higher level entities as if they are going to sleep. Similarly it simulate wakeup of higher level entities as if they are waking up from sleep. Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15sched: group scheduler, fix bloatSrivatsa Vaddagiri
Recent fix to check_preempt_wakeup() to check for preemption at higher levels caused a size bloat for !CONFIG_FAIR_GROUP_SCHED. Fix the problem. 42277 10598 320 53195 cfcb kernel/sched.o-before_this_patch 42216 10598 320 53134 cf8e kernel/sched.o-after_this_patch Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15sched: cleanup, remove stale commentIngo Molnar
cleanup, remove stale comment. Signed-off-by: Ingo Molnar <mingo@elte.hu> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15sched: speed up and simplify vslice calculationsPeter Zijlstra
speed up and simplify vslice calculations. [ From: Mike Galbraith <efault@gmx.de>: build fix ] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15sched: clean up min_vruntime usePeter Zijlstra
clean up min_vruntime use. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15sched: yield fixDmitry Adamushko
fix yield bugs due to the current-not-in-rbtree changes: the task is not in the rbtree so rbtree-removal is a no-no. [ From: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>: build fix. ] also, nice code size reduction: kernel/sched.o: text data bss dec hex filename 38323 3506 24 41853 a37d sched.o.before 38236 3506 24 41766 a326 sched.o.after Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15sched: group scheduler wakeup latency fixSrivatsa Vaddagiri
group scheduler wakeup latency fix: when checking for preemption we must check cross-group too, not just intra-group. Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-15sched: remove set_leftmost()Ingo Molnar
Lee Schermerhorn noticed that set_leftmost() contains dead code, remove this. Reported-by: Lee Schermerhorn <Lee.Schermerhorn@hp.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15sched: max_vruntime() simplificationPeter Zijlstra
max_vruntime() simplification. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-10-15sched: fix sign check error in place_entity()Ingo Molnar
fix sign check error in place_entity() - we'd get excessive latencies due to negatives being converted to large u64's. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-10-15sched: undo some of the recent changesIngo Molnar
undo some of the recent changes that are not needed after all, such as last_min_vruntime. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-10-15sched: remove last_min_vruntime effectIngo Molnar
remove last_min_vruntime use - prepare to remove it. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-10-15sched: entity_key() fixIngo Molnar
entity_key() fix - we'd occasionally end up with a 0 vruntime in the !initial case. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-10-15sched debug: check spreadPeter Zijlstra
debug feature: check how well we schedule within a reasonable vruntime 'spread' range. (note that CPU overload can increase the spread, so this is not a hard condition, but normal loads should be within the spread.) Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
2007-10-15sched: add vslicePeter Zijlstra
add vslice: the load-dependent "virtual slice" a task should run ideally, so that the observed latency stays within the sched_latency window. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15sched: remove unneeded tunablesIngo Molnar
remove unneeded tunables. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15sched: clean up code under CONFIG_FAIR_GROUP_SCHEDSrivatsa Vaddagiri
With the view of supporting user-id based fair scheduling (and not just container-based fair scheduling), this patch renames several functions and makes them independent of whether they are being used for container or user-id based fair scheduling. Also fix a problem reported by KAMEZAWA Hiroyuki (wrt allocating less-sized array for tg->cfs_rq[] and tf->se[]). Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-15sched: print &rq->cfs statsSrivatsa Vaddagiri
- Print &rq->cfs statistics as well (useful for group scheduling) Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
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