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2011-07-22Merge branch 'core-locking-for-linus' of ↵Linus Torvalds1-2/+2
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: lockdep: Fix lockdep_no_validate against IRQ states mutex: Make mutex_destroy() an inline function plist: Remove the need to supply locks to plist heads lockup detector: Fix reference to the non-existent CONFIG_DETECT_SOFTLOCKUP option
2011-07-21sched: Separate group-scheduling code more clearlyJan H. Schönherr1-24/+19
Clean up cfs/rt runqueue initialization by moving group scheduling related code into the corresponding functions. Also, keep group scheduling as an add-on, so that things are only done additionally, i. e. remove the init_*_rq() calls from init_tg_*_entry(). (This removes a redundant initalization during sched_init()). In case of group scheduling rt_rq->highest_prio.curr is now initialized twice, but adding another #ifdef seems not worth it. Signed-off-by: Jan H. Schönherr <schnhrr@cs.tu-berlin.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1310661163-16606-1-git-send-email-schnhrr@cs.tu-berlin.de Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-07-21sched: Reorder root_domain to remove 64 bit alignment paddingRichard Kennedy1-1/+1
Reorder root_domain to remove 8 bytes of alignment padding on 64 bit builds, this shrinks the size from 1736 to 1728 bytes, therefore using one fewer cachelines. Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1310726492.1977.5.camel@castor.rsk Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-07-21sched: Do not attempt to destroy uninitialized rt_bandwidthBianca Lutz1-1/+2
If a task group is to be created and alloc_fair_sched_group() fails, then the rt_bandwidth of the corresponding task group is not yet initialized. The caller, sched_create_group(), starts a clean up procedure which calls free_rt_sched_group() which unconditionally destroys the not yet initialized rt_bandwidth. This crashes or hangs the system in lock_hrtimer_base(): UP systems dereference a NULL pointer, while SMP systems loop endlessly on a condition that cannot become true. This patch simply avoids the destruction of rt_bandwidth when the initialization code path was not reached. (This was discovered by accident with a custom kernel modification.) Signed-off-by: Bianca Lutz <sowilo@cs.tu-berlin.de> Signed-off-by: Jan Schoenherr <schnhrr@cs.tu-berlin.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1310580816-10861-7-git-send-email-schnhrr@cs.tu-berlin.de Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-07-21sched: Fix (harmless) typo 'CONFG_FAIR_GROUP_SCHED'Jan Schoenherr1-1/+1
This patch fixes a typo located in a comment. Signed-off-by: Jan Schoenherr <schnhrr@cs.tu-berlin.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1310580816-10861-2-git-send-email-schnhrr@cs.tu-berlin.de Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-07-21sched, cgroup: Optimize load_balance_fair()Peter Zijlstra1-32/+0
Use for_each_leaf_cfs_rq() instead of list_for_each_entry_rcu(), this achieves that load_balance_fair() only iterates those task_groups that actually have tasks on busiest, and that we iterate bottom-up, trying to move light groups before the heavier ones. No idea if it will actually work out to be beneficial in practice, does anybody have a cgroup workload that might show a difference one way or the other? [ Also move update_h_load to sched_fair.c, loosing #ifdef-ery ] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Reviewed-by: Paul Turner <pjt@google.com> Link: http://lkml.kernel.org/r/1310557009.2586.28.camel@twins Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-07-21Merge branch 'linus' into sched/coreIngo Molnar1-46/+199
Merge reason: pick up the latest scheduler fixes. Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-07-20Merge branch 'core-urgent-for-linus' of ↵Linus Torvalds1-6/+38
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: signal: align __lock_task_sighand() irq disabling and RCU softirq,rcu: Inform RCU of irq_exit() activity sched: Add irq_{enter,exit}() to scheduler_ipi() rcu: protect __rcu_read_unlock() against scheduler-using irq handlers rcu: Streamline code produced by __rcu_read_unlock() rcu: Fix RCU_BOOST race handling current->rcu_read_unlock_special rcu: decrease rcu_report_exp_rnp coupling with scheduler
2011-07-20Merge branch 'rcu/urgent' of ↵Ingo Molnar1-6/+38
git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-2.6-rcu into core/urgent
2011-07-20sched: Add irq_{enter,exit}() to scheduler_ipi()Peter Zijlstra1-6/+38
Ensure scheduler_ipi() calls irq_{enter,exit} when it does some actual work. Traditionally we never did any actual work from the resched IPI and all magic happened in the return from interrupt path. Now that we do do some work, we need to ensure irq_{enter,exit} are called so that we don't confuse things. This affects things like timekeeping, NO_HZ and RCU, basically everything with a hook in irq_enter/exit. Explicit examples of things going wrong are: sched_clock_cpu() -- has a callback when leaving NO_HZ state to take a new reading from GTOD and TSC. Without this callback, time is stuck in the past. RCU -- needs in_irq() to work in order to avoid some nasty deadlocks Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2011-07-20sched: Avoid creating superfluous NUMA domains on non-NUMA systemsPeter Zijlstra1-0/+2
When creating sched_domains, stop when we've covered the entire target span instead of continuing to create domains, only to later find they're redundant and throw them away again. This avoids single node systems from touching funny NUMA sched_domain creation code and reduces the risks of the new SD_OVERLAP code. Requested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Anton Blanchard <anton@samba.org> Cc: mahesh@linux.vnet.ibm.com Cc: benh@kernel.crashing.org Cc: linuxppc-dev@lists.ozlabs.org Link: http://lkml.kernel.org/r/1311180177.29152.57.camel@twins Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-07-20sched: Allow for overlapping sched_domain spansPeter Zijlstra1-29/+128
Allow for sched_domain spans that overlap by giving such domains their own sched_group list instead of sharing the sched_groups amongst each-other. This is needed for machines with more than 16 nodes, because sched_domain_node_span() will generate a node mask from the 16 nearest nodes without regard if these masks have any overlap. Currently sched_domains have a sched_group that maps to their child sched_domain span, and since there is no overlap we share the sched_group between the sched_domains of the various CPUs. If however there is overlap, we would need to link the sched_group list in different ways for each cpu, and hence sharing isn't possible. In order to solve this, allocate private sched_groups for each CPU's sched_domain but have the sched_groups share a sched_group_power structure such that we can uniquely track the power. Reported-and-tested-by: Anton Blanchard <anton@samba.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/n/tip-08bxqw9wis3qti9u5inifh3y@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-07-20sched: Break out cpu_power from the sched_group structurePeter Zijlstra1-6/+26
In order to prepare for non-unique sched_groups per domain, we need to carry the cpu_power elsewhere, so put a level of indirection in. Reported-and-tested-by: Anton Blanchard <anton@samba.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/n/tip-qkho2byuhe4482fuknss40ad@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-07-15sched: Fix 32bit racePeter Zijlstra1-0/+3
Commit 3fe1698b7fe0 ("sched: Deal with non-atomic min_vruntime reads on 32bit") forgot to initialize min_vruntime_copy which could lead to an infinite while loop in task_waking_fair() under some circumstances (early boot, lucky timing). [ This bug was also reported by others that blamed it on the RCU initialization problems ] Reported-and-tested-by: Bruno Wolff III <bruno@wolff.to> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-14sched: adjust scheduler cpu power for stolen timeGlauber Costa1-10/+37
This patch makes update_rq_clock() aware of steal time. The mechanism of operation is not different from irq_time, and follows the same principles. This lives in a CONFIG option itself, and can be compiled out independently of the rest of steal time reporting. The effect of disabling it is that the scheduler will still report steal time (that cannot be disabled), but won't use this information for cpu power adjustments. Everytime update_rq_clock_task() is invoked, we query information about how much time was stolen since last call, and feed it into sched_rt_avg_update(). Although steal time reporting in account_process_tick() keeps track of the last time we read the steal clock, in prev_steal_time, this patch do it independently using another field, prev_steal_time_rq. This is because otherwise, information about time accounted in update_process_tick() would never reach us in update_rq_clock(). Signed-off-by: Glauber Costa <glommer@redhat.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Tested-by: Eric B Munson <emunson@mgebm.net> CC: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> CC: Anthony Liguori <aliguori@us.ibm.com> Signed-off-by: Avi Kivity <avi@redhat.com>
2011-07-14KVM guest: Steal time accountingGlauber Costa1-0/+43
This patch accounts steal time time in account_process_tick. If one or more tick is considered stolen in the current accounting cycle, user/system accounting is skipped. Idle is fine, since the hypervisor does not report steal time if the guest is halted. Accounting steal time from the core scheduler give us the advantage of direct acess to the runqueue data. In a later opportunity, it can be used to tweak cpu power and make the scheduler aware of the time it lost. [avi: <asm/paravirt.h> doesn't exist on many archs] Signed-off-by: Glauber Costa <glommer@redhat.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Tested-by: Eric B Munson <emunson@mgebm.net> CC: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> CC: Anthony Liguori <aliguori@us.ibm.com> Signed-off-by: Avi Kivity <avi@redhat.com>
2011-07-11Merge branch 'master' into for-nextJiri Kosina1-6/+3
Sync with Linus' tree to be able to apply pending patches that are based on newer code already present upstream.
2011-07-08rcu: treewide: Do not use rcu_read_lock_held when calling rcu_dereference_checkMichal Hocko1-1/+0
Since ca5ecddf (rcu: define __rcu address space modifier for sparse) rcu_dereference_check use rcu_read_lock_held as a part of condition automatically so callers do not have to do that as well. Signed-off-by: Michal Hocko <mhocko@suse.cz> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2011-07-08plist: Remove the need to supply locks to plist headsDima Zavin1-2/+2
This was legacy code brought over from the RT tree and is no longer necessary. Signed-off-by: Dima Zavin <dima@android.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Cc: Daniel Walker <dwalker@codeaurora.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andi Kleen <andi@firstfloor.org> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Link: http://lkml.kernel.org/r/1310084879-10351-2-git-send-email-dima@android.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-07-01Merge branch 'sched/core-v2' of ↵Ingo Molnar1-4/+2
git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing into sched/core
2011-07-01perf: Remove the nmi parameter from the swevent and overflow interfacePeter Zijlstra1-1/+1
The nmi parameter indicated if we could do wakeups from the current context, if not, we would set some state and self-IPI and let the resulting interrupt do the wakeup. For the various event classes: - hardware: nmi=0; PMI is in fact an NMI or we run irq_work_run from the PMI-tail (ARM etc.) - tracepoint: nmi=0; since tracepoint could be from NMI context. - software: nmi=[0,1]; some, like the schedule thing cannot perform wakeups, and hence need 0. As one can see, there is very little nmi=1 usage, and the down-side of not using it is that on some platforms some software events can have a jiffy delay in wakeup (when arch_irq_work_raise isn't implemented). The up-side however is that we can remove the nmi parameter and save a bunch of conditionals in fast paths. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Michael Cree <mcree@orcon.net.nz> Cc: Will Deacon <will.deacon@arm.com> Cc: Deng-Cheng Zhu <dengcheng.zhu@gmail.com> Cc: Anton Blanchard <anton@samba.org> Cc: Eric B Munson <emunson@mgebm.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Paul Mundt <lethal@linux-sh.org> Cc: David S. Miller <davem@davemloft.net> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Jason Wessel <jason.wessel@windriver.com> Cc: Don Zickus <dzickus@redhat.com> Link: http://lkml.kernel.org/n/tip-agjev8eu666tvknpb3iaj0fg@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-07-01sched: Simplify mutex_spin_on_owner()Thomas Gleixner1-16/+9
It does not make sense to rcu_read_lock/unlock() in every loop iteration while spinning on the mutex. Move the rcu protection outside the loop. Also simplify the return path to always check for lock->owner == NULL which meets the requirements of both owner changed and need_resched() caused loop exits. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1106101458350.11814@ionos Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-07-01Merge commit 'v3.0-rc5' into sched/coreIngo Molnar1-5/+16
Merge reason: Move to a (much) newer base. Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-07-01sched, cgroups: Fix MIN_SHARES on 64-bit boxenMike Galbraith1-6/+3
Commit c8b28116 ("sched: Increase SCHED_LOAD_SCALE resolution") intended to have no user-visible effect, but allows setting cpu.shares to < MIN_SHARES, which the user then sees. Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Nikhil Rao <ncrao@google.com> Link: http://lkml.kernel.org/r/1307192600.8618.3.camel@marge.simson.net Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-06-23sched: Generalize sleep inside spinlock detectionFrederic Weisbecker1-1/+1
The sleeping inside spinlock detection is actually used for more general sleeping inside atomic sections debugging: preemption disabled, rcu read side critical sections, interrupts, interrupt disabled, etc... Change the name of the config and its help section to reflect its more general role. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Randy Dunlap <randy.dunlap@oracle.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Ingo Molnar <mingo@elte.hu>
2011-06-10sched: Isolate preempt counting in its own config optionFrederic Weisbecker1-1/+1
Create a new CONFIG_PREEMPT_COUNT that handles the inc/dec of preempt count offset independently. So that the offset can be updated by preempt_disable() and preempt_enable() even without the need for CONFIG_PREEMPT beeing set. This prepares to make CONFIG_DEBUG_SPINLOCK_SLEEP working with !CONFIG_PREEMPT where it currently doesn't detect code that sleeps inside explicit preemption disabled sections. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
2011-06-07sched: Remove pointless in_atomic() definition checkFrederic Weisbecker1-2/+0
It's really supposed to be defined here. If it's not then we actually want the build to crash so that we know it, and not keep it silent. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
2011-06-07sched: Fix/clarify set_task_cpu() locking rulesPeter Zijlstra1-5/+16
Sergey reported a CONFIG_PROVE_RCU warning in push_rt_task where set_task_cpu() was called with both relevant rq->locks held, which should be sufficient for running tasks since holding its rq->lock will serialize against sched_move_task(). Update the comments and fix the task_group() lockdep test. Reported-and-tested-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1307115427.2353.3456.camel@twins Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-06-03Merge branch 'unlikely/sched' of ↵Ingo Molnar1-2/+2
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into sched/urgent
2011-05-31sched: Fix schedstat.nr_wakeups_migratePeter Zijlstra1-4/+7
While looking over the code I found that with the ttwu rework the nr_wakeups_migrate test broke since we now switch cpus prior to calling ttwu_stat(), hence the test is always true. Cure this by passing the migration state in wake_flags. Also move the whole test under CONFIG_SMP, its hard to migrate tasks on UP :-) Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-pwwxl7gdqs5676f1d4cx6pj7@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-31sched: Fix cross-cpu clock sync on remote wakeupsPeter Zijlstra1-0/+1
Markus reported that commit 317f394160e ("sched: Move the second half of ttwu() to the remote cpu") caused some accounting funnies on his AMD Phenom II X4, such as weird 'top' results. It turns out that this is due to non-synced TSC and the queued remote wakeups stopped coupeling the two relevant cpu clocks, which leads to wakeups seeing time jumps, which in turn lead to skewed runtime stats. Add an explicit call to sched_clock_cpu() to couple the per-cpu clocks to restore the normal flow of time. Reported-and-tested-by: Markus Trippelsdorf <markus@trippelsdorf.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1306835745.2353.3.camel@twins Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-28cpuset: Fix cpuset_cpus_allowed_fallback(), don't update tsk->rt.nr_cpus_allowedKOSAKI Motohiro1-7/+12
The rule is, we have to update tsk->rt.nr_cpus_allowed if we change tsk->cpus_allowed. Otherwise RT scheduler may confuse. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/4DD4B3FA.5060901@jp.fujitsu.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-28sched: Fix ttwu() for __ARCH_WANT_INTERRUPTS_ON_CTXSWPeter Zijlstra1-9/+28
Marc reported that e4a52bcb9 (sched: Remove rq->lock from the first half of ttwu()) broke his ARM-SMP machine. Now ARM is one of the few __ARCH_WANT_INTERRUPTS_ON_CTXSW users, so that exception in the ttwu() code was suspect. Yong found that the interrupt could hit after context_switch() changes current but before it clears p->on_cpu, if that interrupt were to attempt a wake-up of p we would indeed find ourselves spinning in IRQ context. Fix this by reverting to the old behaviour for this situation and perform a full remote wake-up. Cc: Frank Rowand <frank.rowand@am.sony.com> Cc: Yong Zhang <yong.zhang0@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Reported-by: Marc Zyngier <Marc.Zyngier@arm.com> Tested-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-26cgroups: add per-thread subsystem callbacksBen Blum1-35/+3
Add cgroup subsystem callbacks for per-thread attachment in atomic contexts Add can_attach_task(), pre_attach(), and attach_task() as new callbacks for cgroups's subsystem interface. Unlike can_attach and attach, these are for per-thread operations, to be called potentially many times when attaching an entire threadgroup. Also, the old "bool threadgroup" interface is removed, as replaced by this. All subsystems are modified for the new interface - of note is cpuset, which requires from/to nodemasks for attach to be globally scoped (though per-cpuset would work too) to persist from its pre_attach to attach_task and attach. This is a pre-patch for cgroup-procs-writable.patch. Signed-off-by: Ben Blum <bblum@andrew.cmu.edu> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Matt Helsley <matthltc@us.ibm.com> Reviewed-by: Paul Menage <menage@google.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-23Merge branch 'sched-core-for-linus' of ↵Linus Torvalds1-12/+27
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: sched: Increase SCHED_LOAD_SCALE resolution sched: Introduce SCHED_POWER_SCALE to scale cpu_power calculations sched: Cleanup set_load_weight()
2011-05-22Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-next-2.6Linus Torvalds1-1/+1
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-next-2.6: (28 commits) sparc32: fix build, fix missing cpu_relax declaration SCHED_TTWU_QUEUE is not longer needed since sparc32 now implements IPI sparc32,leon: Remove unnecessary page_address calls in LEON DMA API. sparc: convert old cpumask API into new one sparc32, sun4d: Implemented SMP IPIs support for SUN4D machines sparc32, sun4m: Implemented SMP IPIs support for SUN4M machines sparc32,leon: Implemented SMP IPIs for LEON CPU sparc32: implement SMP IPIs using the generic functions sparc32,leon: SMP power down implementation sparc32,leon: added some SMP comments sparc: add {read,write}*_be routines sparc32,leon: don't rely on bootloader to mask IRQs sparc32,leon: operate on boot-cpu IRQ controller registers sparc32: always define boot_cpu_id sparc32: removed unused code, implemented by generic code sparc32: avoid build warning at mm/percpu.c:1647 sparc32: always register a PROM based early console sparc32: probe for cpu info only during startup sparc: consolidate show_cpuinfo in cpu.c sparc32,leon: implement genirq CPU affinity ...
2011-05-20SCHED_TTWU_QUEUE is not longer needed since sparc32 now implements IPIDaniel Hellstrom1-1/+1
Signed-off-by: Daniel Hellstrom <daniel@gaisler.com> Reported-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2011-05-20Merge commit '317f394160e9beb97d19a84c39b7e5eb3d7815a8'David S. Miller1-278/+349
Conflicts: arch/sparc/kernel/smp_32.c With merge conflict help from Daniel Hellstrom. Signed-off-by: David S. Miller <davem@davemloft.net>
2011-05-20sched: Increase SCHED_LOAD_SCALE resolutionNikhil Rao1-8/+20
Introduce SCHED_LOAD_RESOLUTION, which scales is added to SCHED_LOAD_SHIFT and increases the resolution of SCHED_LOAD_SCALE. This patch sets the value of SCHED_LOAD_RESOLUTION to 10, scaling up the weights for all sched entities by a factor of 1024. With this extra resolution, we can handle deeper cgroup hiearchies and the scheduler can do better shares distribution and load load balancing on larger systems (especially for low weight task groups). This does not change the existing user interface, the scaled weights are only used internally. We do not modify prio_to_weight values or inverses, but use the original weights when calculating the inverse which is used to scale execution time delta in calc_delta_mine(). This ensures we do not lose accuracy when accounting time to the sched entities. Thanks to Nikunj Dadhania for fixing an bug in c_d_m() that broken fairness. Below is some analysis of the performance costs/improvements of this patch. 1. Micro-arch performance costs: Experiment was to run Ingo's pipe_test_100k 200 times with the task pinned to one cpu. I measured instruction, cycles and stalled-cycles for the runs. See: http://thread.gmane.org/gmane.linux.kernel/1129232/focus=1129389 for more info. -tip (baseline): Performance counter stats for '/root/load-scale/pipe-test-100k' (200 runs): 964,991,769 instructions # 0.82 insns per cycle # 0.33 stalled cycles per insn # ( +- 0.05% ) 1,171,186,635 cycles # 0.000 GHz ( +- 0.08% ) 306,373,664 stalled-cycles-backend # 26.16% backend cycles idle ( +- 0.28% ) 314,933,621 stalled-cycles-frontend # 26.89% frontend cycles idle ( +- 0.34% ) 1.122405684 seconds time elapsed ( +- 0.05% ) -tip+patches: Performance counter stats for './load-scale/pipe-test-100k' (200 runs): 963,624,821 instructions # 0.82 insns per cycle # 0.33 stalled cycles per insn # ( +- 0.04% ) 1,175,215,649 cycles # 0.000 GHz ( +- 0.08% ) 315,321,126 stalled-cycles-backend # 26.83% backend cycles idle ( +- 0.28% ) 316,835,873 stalled-cycles-frontend # 26.96% frontend cycles idle ( +- 0.29% ) 1.122238659 seconds time elapsed ( +- 0.06% ) With this patch, instructions decrease by ~0.10% and cycles increase by 0.27%. This doesn't look statistically significant. The number of stalled cycles in the backend increased from 26.16% to 26.83%. This can be attributed to the shifts we do in c_d_m() and other places. The fraction of stalled cycles in the frontend remains about the same, at 26.96% compared to 26.89% in -tip. 2. Balancing low-weight task groups Test setup: run 50 tasks with random sleep/busy times (biased around 100ms) in a low weight container (with cpu.shares = 2). Measure %idle as reported by mpstat over a 10s window. -tip (baseline): 06:47:48 PM CPU %usr %nice %sys %iowait %irq %soft %steal %guest %idle intr/s 06:47:49 PM all 94.32 0.00 0.06 0.00 0.00 0.00 0.00 0.00 5.62 15888.00 06:47:50 PM all 94.57 0.00 0.62 0.00 0.00 0.00 0.00 0.00 4.81 16180.00 06:47:51 PM all 94.69 0.00 0.06 0.00 0.00 0.00 0.00 0.00 5.25 15966.00 06:47:52 PM all 95.81 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4.19 16053.00 06:47:53 PM all 94.88 0.06 0.00 0.00 0.00 0.00 0.00 0.00 5.06 15984.00 06:47:54 PM all 93.31 0.00 0.00 0.00 0.00 0.00 0.00 0.00 6.69 15806.00 06:47:55 PM all 94.19 0.00 0.06 0.00 0.00 0.00 0.00 0.00 5.75 15896.00 06:47:56 PM all 92.87 0.00 0.00 0.00 0.00 0.00 0.00 0.00 7.13 15716.00 06:47:57 PM all 94.88 0.00 0.00 0.00 0.00 0.00 0.00 0.00 5.12 15982.00 06:47:58 PM all 95.44 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4.56 16075.00 Average: all 94.49 0.01 0.08 0.00 0.00 0.00 0.00 0.00 5.42 15954.60 -tip+patches: 06:47:03 PM CPU %usr %nice %sys %iowait %irq %soft %steal %guest %idle intr/s 06:47:04 PM all 100.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 16630.00 06:47:05 PM all 99.69 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.31 16580.20 06:47:06 PM all 99.69 0.00 0.06 0.00 0.00 0.00 0.00 0.00 0.25 16596.00 06:47:07 PM all 99.20 0.00 0.74 0.00 0.00 0.06 0.00 0.00 0.00 17838.61 06:47:08 PM all 100.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 16540.00 06:47:09 PM all 100.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 16575.00 06:47:10 PM all 100.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 16614.00 06:47:11 PM all 99.94 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.06 16588.00 06:47:12 PM all 99.94 0.00 0.06 0.00 0.00 0.00 0.00 0.00 0.00 16593.00 06:47:13 PM all 99.94 0.00 0.06 0.00 0.00 0.00 0.00 0.00 0.00 16551.00 Average: all 99.84 0.00 0.09 0.00 0.00 0.01 0.00 0.00 0.06 16711.58 We see an improvement in idle% on the system (drops from 5.42% on -tip to 0.06% with the patches). We see an improvement in idle% on the system (drops from 5.42% on -tip to 0.06% with the patches). Signed-off-by: Nikhil Rao <ncrao@google.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Nikunj A. Dadhania <nikunj@linux.vnet.ibm.com> Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Cc: Stephan Barwolf <stephan.baerwolf@tu-ilmenau.de> Cc: Mike Galbraith <efault@gmx.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/1305754668-18792-1-git-send-email-ncrao@google.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-20sched: Introduce SCHED_POWER_SCALE to scale cpu_power calculationsNikhil Rao1-2/+2
SCHED_LOAD_SCALE is used to increase nice resolution and to scale cpu_power calculations in the scheduler. This patch introduces SCHED_POWER_SCALE and converts all uses of SCHED_LOAD_SCALE for scaling cpu_power to use SCHED_POWER_SCALE instead. This is a preparatory patch for increasing the resolution of SCHED_LOAD_SCALE, and there is no need to increase resolution for cpu_power calculations. Signed-off-by: Nikhil Rao <ncrao@google.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Nikunj A. Dadhania <nikunj@linux.vnet.ibm.com> Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Cc: Stephan Barwolf <stephan.baerwolf@tu-ilmenau.de> Cc: Mike Galbraith <efault@gmx.de> Link: http://lkml.kernel.org/r/1305738580-9924-3-git-send-email-ncrao@google.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-20sched: Cleanup set_load_weight()Nikhil Rao1-4/+7
Avoid using long repetitious names; make this simpler and nicer to read. No functional change introduced in this patch. Signed-off-by: Nikhil Rao <ncrao@google.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Nikunj A. Dadhania <nikunj@linux.vnet.ibm.com> Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Cc: Stephan Barwolf <stephan.baerwolf@tu-ilmenau.de> Cc: Mike Galbraith <efault@gmx.de> Link: http://lkml.kernel.org/r/1305738580-9924-2-git-send-email-ncrao@google.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-16sched: Fix and optimise calculation of the weight-inverseStephan Baerwolf1-3/+3
If the inverse loadweight should be zero, function "calc_delta_mine" calculates the inverse of "lw->weight" (in 32bit integer ops). This calculation is actually a little bit impure (because it is inverting something around "lw-weight"+1), especially when "lw->weight" becomes smaller. The correct inverse would be 1/lw->weight multiplied by "WMULT_CONST" for fixcomma-scaling it into integers. (So WMULT_CONST/lw->weight ...) The old, impure algorithm took two divisions for inverting lw->weight, the new, more exact one only takes one and an additional unlikely-if. Signed-off-by: Stephan Baerwolf <stephan.baerwolf@tu-ilmenau.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/n/tip-0pz0wnyalr4tk4ln11xwumdx@git.kernel.org [ This could explain some aritmetical issues for small shares but nothing concrete has been reported yet so we are not confident enough to queue this up in sched/urgent and for -stable backport. But if anyone finds this commit and sees it to fix some badness then we can certainly change our mind! ] Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-16sched: Avoid going ahead if ->cpus_allowed is not changedYong Zhang1-2/+4
If cpumask_equal(&p->cpus_allowed, new_mask) is true, seems there is no reason to prevent set_cpus_allowed_ptr() return directly. Signed-off-by: Yong Zhang <yong.zhang0@gmail.com> Acked-by: Hillf Danton <dhillf@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20110509140705.GA2219@zhy Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-16sched, rt: Update rq clock when unthrottling of an otherwise idle CPUMike Galbraith1-3/+3
If an RT task is awakened while it's rt_rq is throttled, the time between wakeup/enqueue and unthrottle/selection may be accounted as rt_time if the CPU is idle. Set rq->skip_clock_update negative upon throttle release to tell put_prev_task() that we need a clock update. Reported-by: Thomas Giesel <skoe@directbox.com> Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1304059010.7472.1.camel@marge.simson.net Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-12sched: Remove unused parameters from sched_fork() and wake_up_new_task()Samir Bellabes1-2/+2
sched_fork() and wake_up_new_task() are defined with a parameter 'unsigned long clone_flags', which is unused. This patch removes the parameters. Signed-off-by: Samir Bellabes <sam@synack.fr> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1305130685-1047-1-git-send-email-sam@synack.fr Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-06sched: Shorten the construction of the span cpu mask of sched domainHillf Danton1-3/+5
For a given node, when constructing the cpumask for its sched_domain to span, if there is no best node available after searching, further efforts could be saved, based on small change in the return value of find_next_best_node(). Signed-off-by: Hillf Danton <dhillf@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Yong Zhang <yong.zhang0@gmail.com> Link: http://lkml.kernel.org/r/BANLkTi%3DqPWxRAa6%2BdT3ohEP6Z%3D0v%2Be4EXA@mail.gmail.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-06sched: Wrap the 'cfs_rq->nr_spread_over' field with CONFIG_SCHED_DEBUGRakib Mullick1-0/+2
cfs_rq->nr_spread_over is only used when CONFIG_SCHED_DEBUG is set. So wrap it with CONFIG_SCHED_DEBUG. Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1304528026.15681.3.camel@localhost.localdomain Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-04-26sched: Remove noop in alloc_rt_sched_group()Hillf Danton1-3/+0
The rq varible, though computed for each possible cpu, has nothing to do in the function, so it can be removed. This also eliminates a build warning. Signed-off-by: Hillf Danton <dhillf@gmail.com> Reviewed-by: Yong Zhang <yong.zhang0@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/BANLkTin-FfQfqW5ym1iuEmrk8s777Y1LAg@mail.gmail.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-04-24sched: Get rid of lock_depthJonathan Corbet1-10/+1
Neil Brown pointed out that lock_depth somehow escaped the BKL removal work. Let's get rid of it now. Note that the perf scripting utilities still have a bunch of code for dealing with common_lock_depth in tracepoints; I have left that in place in case anybody wants to use that code with older kernels. Suggested-by: Neil Brown <neilb@suse.de> Signed-off-by: Jonathan Corbet <corbet@lwn.net> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20110422111910.456c0e84@bike.lwn.net Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-04-21sched: Remove obsolete comment from scheduler_tick()Rakib Mullick1-3/+0
scheduler_tick() is no longer called by fork code - this got discarded a long time ago by commit bc947631d1d532 ("sched: improve efficiency of sched_fork()"). So, remove the comment which still claims otherwise. Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/BANLkTimO4iGP0QpaHO1HHF1QOnVcQpc0cw@mail.gmail.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
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