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2016-06-27sched/fair: Fix calc_cfs_shares() fixed point arithmetics width confusionPeter Zijlstra1-16/+11
Commit: fde7d22e01aa ("sched/fair: Fix overly small weight for interactive group entities") did something non-obvious but also did it buggy yet latent. The problem was exposed for real by a later commit in the v4.7 merge window: 2159197d6677 ("sched/core: Enable increased load resolution on 64-bit kernels") ... after which tg->load_avg and cfs_rq->load.weight had different units (10 bit fixed point and 20 bit fixed point resp.). Add a comment to explain the use of cfs_rq->load.weight over the 'natural' cfs_rq->avg.load_avg and add scale_load_down() to correct for the difference in unit. Since this is (now, as per a previous commit) the only user of calc_tg_weight(), collapse it. The effects of this bug should be randomly inconsistent SMP-balancing of cgroups workloads. Reported-by: Jirka Hladky <jhladky@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: 2159197d6677 ("sched/core: Enable increased load resolution on 64-bit kernels") Fixes: fde7d22e01aa ("sched/fair: Fix overly small weight for interactive group entities") Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-27sched/fair: Fix effective_load() to consistently use smoothed loadPeter Zijlstra1-6/+9
Starting with the following commit: fde7d22e01aa ("sched/fair: Fix overly small weight for interactive group entities") calc_tg_weight() doesn't compute the right value as expected by effective_load(). The difference is in the 'correction' term. In order to ensure \Sum rw_j >= rw_i we cannot use tg->load_avg directly, since that might be lagging a correction on the current cfs_rq->avg.load_avg value. Therefore we use tg->load_avg - cfs_rq->tg_load_avg_contrib + cfs_rq->avg.load_avg. Now, per the referenced commit, calc_tg_weight() doesn't use cfs_rq->avg.load_avg, as is later used in @w, but uses cfs_rq->load.weight instead. So stop using calc_tg_weight() and do it explicitly. The effects of this bug are wake_affine() making randomly poor choices in cgroup-intense workloads. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: <stable@vger.kernel.org> # v4.3+ Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: fde7d22e01aa ("sched/fair: Fix overly small weight for interactive group entities") Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-24sched/core: Allow kthreads to fall back to online && !active cpusTejun Heo1-1/+3
During CPU hotplug, CPU_ONLINE callbacks are run while the CPU is online but not active. A CPU_ONLINE callback may create or bind a kthread so that its cpus_allowed mask only allows the CPU which is being brought online. The kthread may start executing before the CPU is made active and can end up in select_fallback_rq(). In such cases, the expected behavior is selecting the CPU which is coming online; however, because select_fallback_rq() only chooses from active CPUs, it determines that the task doesn't have any viable CPU in its allowed mask and ends up overriding it to cpu_possible_mask. CPU_ONLINE callbacks should be able to put kthreads on the CPU which is coming online. Update select_fallback_rq() so that it follows cpu_online() rather than cpu_active() for kthreads. Reported-by: Gautham R Shenoy <ego@linux.vnet.ibm.com> Tested-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Abdul Haleem <abdhalee@linux.vnet.ibm.com> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: kernel-team@fb.com Cc: linuxppc-dev@lists.ozlabs.org Link: http://lkml.kernel.org/r/20160616193504.GB3262@mtj.duckdns.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-24sched/fair: Do not announce throttled next buddy in dequeue_task_fair()Konstantin Khlebnikov1-5/+4
Hierarchy could be already throttled at this point. Throttled next buddy could trigger a NULL pointer dereference in pick_next_task_fair(). Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Ben Segall <bsegall@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/146608183552.21905.15924473394414832071.stgit@buzz Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-24sched/fair: Initialize throttle_count for new task-groups lazilyKonstantin Khlebnikov2-1/+21
Cgroup created inside throttled group must inherit current throttle_count. Broken throttle_count allows to nominate throttled entries as a next buddy, later this leads to null pointer dereference in pick_next_task_fair(). This patch initialize cfs_rq->throttle_count at first enqueue: laziness allows to skip locking all rq at group creation. Lazy approach also allows to skip full sub-tree scan at throttling hierarchy (not in this patch). Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: bsegall@google.com Link: http://lkml.kernel.org/r/146608182119.21870.8439834428248129633.stgit@buzz Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-20sched/fair: Fix cfs_rq avg tracking underflowPeter Zijlstra1-8/+25
As per commit: b7fa30c9cc48 ("sched/fair: Fix post_init_entity_util_avg() serialization") > the code generated from update_cfs_rq_load_avg(): > > if (atomic_long_read(&cfs_rq->removed_load_avg)) { > s64 r = atomic_long_xchg(&cfs_rq->removed_load_avg, 0); > sa->load_avg = max_t(long, sa->load_avg - r, 0); > sa->load_sum = max_t(s64, sa->load_sum - r * LOAD_AVG_MAX, 0); > removed_load = 1; > } > > turns into: > > ffffffff81087064: 49 8b 85 98 00 00 00 mov 0x98(%r13),%rax > ffffffff8108706b: 48 85 c0 test %rax,%rax > ffffffff8108706e: 74 40 je ffffffff810870b0 <update_blocked_averages+0xc0> > ffffffff81087070: 4c 89 f8 mov %r15,%rax > ffffffff81087073: 49 87 85 98 00 00 00 xchg %rax,0x98(%r13) > ffffffff8108707a: 49 29 45 70 sub %rax,0x70(%r13) > ffffffff8108707e: 4c 89 f9 mov %r15,%rcx > ffffffff81087081: bb 01 00 00 00 mov $0x1,%ebx > ffffffff81087086: 49 83 7d 70 00 cmpq $0x0,0x70(%r13) > ffffffff8108708b: 49 0f 49 4d 70 cmovns 0x70(%r13),%rcx > > Which you'll note ends up with sa->load_avg -= r in memory at > ffffffff8108707a. So I _should_ have looked at other unserialized users of ->load_avg, but alas. Luckily nikbor reported a similar /0 from task_h_load() which instantly triggered recollection of this here problem. Aside from the intermediate value hitting memory and causing problems, there's another problem: the underflow detection relies on the signed bit. This reduces the effective width of the variables, IOW its effectively the same as having these variables be of signed type. This patch changes to a different means of unsigned underflow detection to not rely on the signed bit. This allows the variables to use the 'full' unsigned range. And it does so with explicit LOAD - STORE to ensure any intermediate value will never be visible in memory, allowing these unserialized loads. Note: GCC generates crap code for this, might warrant a look later. Note2: I say 'full' above, if we end up at U*_MAX we'll still explode; maybe we should do clamping on add too. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Yuyang Du <yuyang.du@intel.com> Cc: bsegall@google.com Cc: kernel@kyup.com Cc: morten.rasmussen@arm.com Cc: pjt@google.com Cc: steve.muckle@linaro.org Fixes: 9d89c257dfb9 ("sched/fair: Rewrite runnable load and utilization average tracking") Link: http://lkml.kernel.org/r/20160617091948.GJ30927@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-14kernel/sysrq, watchdog, sched/core: Reset watchdog on all CPUs while ↵Andrey Ryabinin1-2/+4
processing sysrq-w Lengthy output of sysrq-w may take a lot of time on slow serial console. Currently we reset NMI-watchdog on the current CPU to avoid spurious lockup messages. Sometimes this doesn't work since softlockup watchdog might trigger on another CPU which is waiting for an IPI to proceed. We reset softlockup watchdogs on all CPUs, but we do this only after listing all tasks, and this may be too late on a busy system. So, reset watchdogs CPUs earlier, in for_each_process_thread() loop. Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: <stable@vger.kernel.org> Link: http://lkml.kernel.org/r/1465474805-14641-1-git-send-email-aryabinin@virtuozzo.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-14sched/debug: Fix deadlock when enabling sched eventsJosh Poimboeuf1-1/+1
I see a hang when enabling sched events: echo 1 > /sys/kernel/debug/tracing/events/sched/enable The printk buffer shows: BUG: spinlock recursion on CPU#1, swapper/1/0 lock: 0xffff88007d5d8c00, .magic: dead4ead, .owner: swapper/1/0, .owner_cpu: 1 CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.7.0-rc2+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.8.1-20150318_183358- 04/01/2014 ... Call Trace: <IRQ> [<ffffffff8143d663>] dump_stack+0x85/0xc2 [<ffffffff81115948>] spin_dump+0x78/0xc0 [<ffffffff81115aea>] do_raw_spin_lock+0x11a/0x150 [<ffffffff81891471>] _raw_spin_lock+0x61/0x80 [<ffffffff810e5466>] ? try_to_wake_up+0x256/0x4e0 [<ffffffff810e5466>] try_to_wake_up+0x256/0x4e0 [<ffffffff81891a0a>] ? _raw_spin_unlock_irqrestore+0x4a/0x80 [<ffffffff810e5705>] wake_up_process+0x15/0x20 [<ffffffff810cebb4>] insert_work+0x84/0xc0 [<ffffffff810ced7f>] __queue_work+0x18f/0x660 [<ffffffff810cf9a6>] queue_work_on+0x46/0x90 [<ffffffffa00cd95b>] drm_fb_helper_dirty.isra.11+0xcb/0xe0 [drm_kms_helper] [<ffffffffa00cdac0>] drm_fb_helper_sys_imageblit+0x30/0x40 [drm_kms_helper] [<ffffffff814babcd>] soft_cursor+0x1ad/0x230 [<ffffffff814ba379>] bit_cursor+0x649/0x680 [<ffffffff814b9d30>] ? update_attr.isra.2+0x90/0x90 [<ffffffff814b5e6a>] fbcon_cursor+0x14a/0x1c0 [<ffffffff81555ef8>] hide_cursor+0x28/0x90 [<ffffffff81558b6f>] vt_console_print+0x3bf/0x3f0 [<ffffffff81122c63>] call_console_drivers.constprop.24+0x183/0x200 [<ffffffff811241f4>] console_unlock+0x3d4/0x610 [<ffffffff811247f5>] vprintk_emit+0x3c5/0x610 [<ffffffff81124bc9>] vprintk_default+0x29/0x40 [<ffffffff811e965b>] printk+0x57/0x73 [<ffffffff810f7a9e>] enqueue_entity+0xc2e/0xc70 [<ffffffff810f7b39>] enqueue_task_fair+0x59/0xab0 [<ffffffff8106dcd9>] ? kvm_sched_clock_read+0x9/0x20 [<ffffffff8103fb39>] ? sched_clock+0x9/0x10 [<ffffffff810e3fcc>] activate_task+0x5c/0xa0 [<ffffffff810e4514>] ttwu_do_activate+0x54/0xb0 [<ffffffff810e5cea>] sched_ttwu_pending+0x7a/0xb0 [<ffffffff810e5e51>] scheduler_ipi+0x61/0x170 [<ffffffff81059e7f>] smp_trace_reschedule_interrupt+0x4f/0x2a0 [<ffffffff81893ba6>] trace_reschedule_interrupt+0x96/0xa0 <EOI> [<ffffffff8106e0d6>] ? native_safe_halt+0x6/0x10 [<ffffffff8110fb1d>] ? trace_hardirqs_on+0xd/0x10 [<ffffffff81040ac0>] default_idle+0x20/0x1a0 [<ffffffff8104147f>] arch_cpu_idle+0xf/0x20 [<ffffffff81102f8f>] default_idle_call+0x2f/0x50 [<ffffffff8110332e>] cpu_startup_entry+0x37e/0x450 [<ffffffff8105af70>] start_secondary+0x160/0x1a0 Note the hang only occurs when echoing the above from a physical serial console, not from an ssh session. The bug is caused by a deadlock where the task is trying to grab the rq lock twice because printk()'s aren't safe in sched code. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Fixes: cb2517653fcc ("sched/debug: Make schedstats a runtime tunable that is disabled by default") Link: http://lkml.kernel.org/r/20160613073209.gdvdybiruljbkn3p@treble Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-14sched/fair: Fix post_init_entity_util_avg() serializationPeter Zijlstra2-3/+8
Chris Wilson reported a divide by 0 at: post_init_entity_util_avg(): > 725 if (cfs_rq->avg.util_avg != 0) { > 726 sa->util_avg = cfs_rq->avg.util_avg * se->load.weight; > -> 727 sa->util_avg /= (cfs_rq->avg.load_avg + 1); > 728 > 729 if (sa->util_avg > cap) > 730 sa->util_avg = cap; > 731 } else { Which given the lack of serialization, and the code generated from update_cfs_rq_load_avg() is entirely possible: if (atomic_long_read(&cfs_rq->removed_load_avg)) { s64 r = atomic_long_xchg(&cfs_rq->removed_load_avg, 0); sa->load_avg = max_t(long, sa->load_avg - r, 0); sa->load_sum = max_t(s64, sa->load_sum - r * LOAD_AVG_MAX, 0); removed_load = 1; } turns into: ffffffff81087064: 49 8b 85 98 00 00 00 mov 0x98(%r13),%rax ffffffff8108706b: 48 85 c0 test %rax,%rax ffffffff8108706e: 74 40 je ffffffff810870b0 ffffffff81087070: 4c 89 f8 mov %r15,%rax ffffffff81087073: 49 87 85 98 00 00 00 xchg %rax,0x98(%r13) ffffffff8108707a: 49 29 45 70 sub %rax,0x70(%r13) ffffffff8108707e: 4c 89 f9 mov %r15,%rcx ffffffff81087081: bb 01 00 00 00 mov $0x1,%ebx ffffffff81087086: 49 83 7d 70 00 cmpq $0x0,0x70(%r13) ffffffff8108708b: 49 0f 49 4d 70 cmovns 0x70(%r13),%rcx Which you'll note ends up with 'sa->load_avg - r' in memory at ffffffff8108707a. By calling post_init_entity_util_avg() under rq->lock we're sure to be fully serialized against PELT updates and cannot observe intermediate state like this. Reported-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Yuyang Du <yuyang.du@intel.com> Cc: bsegall@google.com Cc: morten.rasmussen@arm.com Cc: pjt@google.com Cc: steve.muckle@linaro.org Fixes: 2b8c41daba32 ("sched/fair: Initiate a new task's util avg to a bounded value") Link: http://lkml.kernel.org/r/20160609130750.GQ30909@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-10Merge branch 'stacking-fixes' (vfs stacking fixes from Jann)Linus Torvalds1-1/+2
Merge filesystem stacking fixes from Jann Horn. * emailed patches from Jann Horn <jannh@google.com>: sched: panic on corrupted stack end ecryptfs: forbid opening files without mmap handler proc: prevent stacking filesystems on top
2016-06-10sched: panic on corrupted stack endJann Horn1-1/+2
Until now, hitting this BUG_ON caused a recursive oops (because oops handling involves do_exit(), which calls into the scheduler, which in turn raises an oops), which caused stuff below the stack to be overwritten until a panic happened (e.g. via an oops in interrupt context, caused by the overwritten CPU index in the thread_info). Just panic directly. Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-10Merge branch 'sched-urgent-for-linus' of ↵Linus Torvalds3-16/+28
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler fixes from Ingo Molnar: "Two scheduler debugging fixes" * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/debug: Fix 'schedstats=enable' cmdline option sched/debug: Fix /proc/sched_debug regression
2016-06-09Merge branches 'pm-cpufreq-fixes' and 'pm-cpuidle'Rafael J. Wysocki1-1/+1
* pm-cpufreq-fixes: cpufreq: intel_pstate: Fix ->set_policy() interface for no_turbo cpufreq: intel_pstate: Fix code ordering in intel_pstate_set_policy() * pm-cpuidle: cpuidle: Do not access cpuidle_devices when !CONFIG_CPU_IDLE
2016-06-08sched/debug: Fix 'schedstats=enable' cmdline optionJosh Poimboeuf1-5/+21
The 'schedstats=enable' option doesn't work, and also produces the following warning during boot: WARNING: CPU: 0 PID: 0 at /home/jpoimboe/git/linux/kernel/jump_label.c:61 static_key_slow_inc+0x8c/0xa0 static_key_slow_inc used before call to jump_label_init Modules linked in: CPU: 0 PID: 0 Comm: swapper Not tainted 4.7.0-rc1+ #25 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.8.1-20150318_183358- 04/01/2014 0000000000000086 3ae3475a4bea95d4 ffffffff81e03da8 ffffffff8143fc83 ffffffff81e03df8 0000000000000000 ffffffff81e03de8 ffffffff810b1ffb 0000003d00000096 ffffffff823514d0 ffff88007ff197c8 0000000000000000 Call Trace: [<ffffffff8143fc83>] dump_stack+0x85/0xc2 [<ffffffff810b1ffb>] __warn+0xcb/0xf0 [<ffffffff810b207f>] warn_slowpath_fmt+0x5f/0x80 [<ffffffff811e9c0c>] static_key_slow_inc+0x8c/0xa0 [<ffffffff810e07c6>] static_key_enable+0x16/0x40 [<ffffffff8216d633>] setup_schedstats+0x29/0x94 [<ffffffff82148a05>] unknown_bootoption+0x89/0x191 [<ffffffff810d8617>] parse_args+0x297/0x4b0 [<ffffffff82148d61>] start_kernel+0x1d8/0x4a9 [<ffffffff8214897c>] ? set_init_arg+0x55/0x55 [<ffffffff82148120>] ? early_idt_handler_array+0x120/0x120 [<ffffffff821482db>] x86_64_start_reservations+0x2f/0x31 [<ffffffff82148427>] x86_64_start_kernel+0x14a/0x16d The problem is that it tries to update the 'sched_schedstats' static key before jump labels have been initialized. Changing jump_label_init() to be called earlier before parse_early_param() wouldn't fix it: it would still fail trying to poke_text() because mm isn't yet initialized. Instead, just create a temporary '__sched_schedstats' variable which can be copied to the static key later during sched_init() after jump labels have been initialized. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: cb2517653fcc ("sched/debug: Make schedstats a runtime tunable that is disabled by default") Link: http://lkml.kernel.org/r/453775fe3433bed65731a583e228ccea806d18cd.1465322027.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-08sched/debug: Fix /proc/sched_debug regressionJosh Poimboeuf2-11/+7
Commit: cb2517653fcc ("sched/debug: Make schedstats a runtime tunable that is disabled by default") ... introduced a bug when CONFIG_SCHEDSTATS is enabled and the runtime tunable is disabled (which is the default). The wait-time, sum-exec, and sum-sleep fields are missing from the /proc/sched_debug file in the runnable_tasks section. Fix it with a new schedstat_val() macro which returns the field value when schedstats is enabled and zero otherwise. The macro works with both SCHEDSTATS and !SCHEDSTATS. I put the macro in stats.h since it might end up being useful in other places. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: cb2517653fcc ("sched/debug: Make schedstats a runtime tunable that is disabled by default") Link: http://lkml.kernel.org/r/bcda7c2790cf2ccbe586a28c02dd7b6fe7749a2b.1464994423.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-02cpuidle: Do not access cpuidle_devices when !CONFIG_CPU_IDLECatalin Marinas1-1/+1
The cpuidle_devices per-CPU variable is only defined when CPU_IDLE is enabled. Commit c8cc7d4de7a4 ("sched/idle: Reorganize the idle loop") removed the #ifdef CONFIG_CPU_IDLE around cpuidle_idle_call() with the compiler optimising away __this_cpu_read(cpuidle_devices). However, with CONFIG_UBSAN && !CONFIG_CPU_IDLE, this optimisation no longer happens and the kernel fails to link since cpuidle_devices is not defined. This patch introduces an accessor function for the current CPU cpuidle device (returning NULL when !CONFIG_CPU_IDLE) and uses it in cpuidle_idle_call(). Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Cc: 4.5+ <stable@vger.kernel.org> # 4.5+ Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-05-25Merge branch 'sched-urgent-for-linus' of ↵Linus Torvalds1-7/+11
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler fixes from Ingo Molnar: "Two fixes: one for a lost wakeup, the other to fix the compiler optimizing out preempt operations on ARM64 (and possibly other non-x86 architectures)" * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/core: Fix remote wakeups sched/preempt: Fix preempt_count manipulations
2016-05-25Merge branches 'pm-cpufreq', 'pm-cpuidle' and 'pm-core'Rafael J. Wysocki1-1/+3
* pm-cpufreq: cpufreq: schedutil: Improve prints messages with pr_fmt cpufreq: simplified goto out in cpufreq_register_driver() cpufreq: governor: CPUFREQ_GOV_STOP never fails cpufreq: governor: CPUFREQ_GOV_POLICY_EXIT never fails intel_pstate: Simplify conditional in intel_pstate_set_policy() * pm-cpuidle: cpuidle: Fix cpuidle_state_is_coupled() argument in cpuidle_enter() * pm-core: PM / sleep: Handle failures in device_suspend_late() consistently
2016-05-25sched/core: Fix remote wakeupsPeter Zijlstra1-7/+11
Commit: b5179ac70de8 ("sched/fair: Prepare to fix fairness problems on migration") ... introduced a bug: Mike Galbraith found that it introduced a performance regression, while Paul E. McKenney reported lost wakeups and bisected it to this commit. The reason is that I mis-read ttwu_queue() such that I assumed any wakeup that got a remote queue must have had the task migrated. Since this is not so; we need to transfer this information between queueing the wakeup and actually doing the wakeup. Use a new task_struct::sched_flag for this, we already write to sched_contributes_to_load in the wakeup path so this is a hot and modified cacheline. Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reported-by: Mike Galbraith <umgwanakikbuti@gmail.com> Tested-by: Mike Galbraith <umgwanakikbuti@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Hunter <ahh@google.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Ben Segall <bsegall@google.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: Morten Rasmussen <morten.rasmussen@arm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paul Turner <pjt@google.com> Cc: Pavan Kondeti <pkondeti@codeaurora.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: byungchul.park@lge.com Fixes: b5179ac70de8 ("sched/fair: Prepare to fix fairness problems on migration") Link: http://lkml.kernel.org/r/20160523091907.GD15728@worktop.ger.corp.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-05-19cpufreq: schedutil: Improve prints messages with pr_fmtViresh Kumar1-1/+3
Prefix print messages with KBUILD_MODNAME, i.e 'cpufreq_schedutil: '. This helps to keep similar formatting for all the print messages particular to a file and identify those easily in kernel logs. Its already done this way for rest of the governors. Along with that, remove the (now) redundant bits from a print message. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2016-05-16Merge tag 'pm-4.7-rc1' of ↵Linus Torvalds4-11/+576
git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm Pull power management updates from Rafael Wysocki: "The majority of changes go into the cpufreq subsystem this time. To me, quite obviously, the biggest ticket item is the new "schedutil" governor. Interestingly enough, it's the first new cpufreq governor since the beginning of the git era (except for some out-of-the-tree ones). There are two main differences between it and the existing governors. First, it uses the information provided by the scheduler directly for making its decisions, so it doesn't have to track anything by itself. Second, it can invoke drivers (supporting that feature) to adjust CPU performance right away without having to spawn work items to be executed in process context or similar. Currently, the acpi-cpufreq driver is the only one supporting that mode of operation, but then it is used on a large number of systems. The "schedutil" governor as included here is very simple and mostly regarded as a foundation for future work on the integration of the scheduler with CPU power management (in fact, there is work in progress on top of it already). Nevertheless it works and the preliminary results obtained with it are encouraging. There also is some consolidation of CPU frequency management for ARM platforms that can add their machine IDs the the new stub dt-platdev driver now and that will take care of creating the requisite platform device for cpufreq-dt, so it is not necessary to do that in platform code any more. Several ARM platforms are switched over to using this generic mechanism. In addition to that, the intel_pstate driver is now going to respect CPU frequency limits set by the platform firmware (or a BMC) and provided via the ACPI _PPC object. The devfreq subsystem is getting a new "passive" governor for SoCs subsystems that will depend on somebody else to manage their voltage rails and its support for Samsung Exynos SoCs is consolidated. The rest is support for new hardware (Intel Broxton support in intel_idle for one example), bug fixes, optimizations and cleanups in a number of places. Specifics: - New cpufreq "schedutil" governor (making decisions based on CPU utilization information provided by the scheduler and capable of switching CPU frequencies right away if the underlying driver supports that) and support for fast frequency switching in the acpi-cpufreq driver (Rafael Wysocki) - Consolidation of CPU frequency management on ARM platforms allowing them to get rid of some platform-specific boilerplate code if they are going to use the cpufreq-dt driver (Viresh Kumar, Finley Xiao, Marc Gonzalez) - Support for ACPI _PPC and CPU frequency limits in the intel_pstate driver (Srinivas Pandruvada) - Fixes and cleanups in the cpufreq core and generic governor code (Rafael Wysocki, Sai Gurrappadi) - intel_pstate driver optimizations and cleanups (Rafael Wysocki, Philippe Longepe, Chen Yu, Joe Perches) - cpufreq powernv driver fixes and cleanups (Akshay Adiga, Shilpasri Bhat) - cpufreq qoriq driver fixes and cleanups (Jia Hongtao) - ACPI cpufreq driver cleanups (Viresh Kumar) - Assorted cpufreq driver updates (Ashwin Chaugule, Geliang Tang, Javier Martinez Canillas, Paul Gortmaker, Sudeep Holla) - Assorted cpufreq fixes and cleanups (Joe Perches, Arnd Bergmann) - Fixes and cleanups in the OPP (Operating Performance Points) framework, mostly related to OPP sharing, and reorganization of OF-dependent code in it (Viresh Kumar, Arnd Bergmann, Sudeep Holla) - New "passive" governor for devfreq (for SoC subsystems that will rely on someone else for the management of their power resources) and consolidation of devfreq support for Exynos platforms, coding style and typo fixes for devfreq (Chanwoo Choi, MyungJoo Ham) - PM core fixes and cleanups, mostly to make it work better with the generic power domains (genpd) framework, and updates for that framework (Ulf Hansson, Thierry Reding, Colin Ian King) - Intel Broxton support for the intel_idle driver (Len Brown) - cpuidle core optimization and fix (Daniel Lezcano, Dave Gerlach) - ARM cpuidle cleanups (Jisheng Zhang) - Intel Kabylake support for the RAPL power capping driver (Jacob Pan) - AVS (Adaptive Voltage Switching) rockchip-io driver update (Heiko Stuebner) - Updates for the cpupower tool (Arjun Sreedharan, Colin Ian King, Mattia Dongili, Thomas Renninger)" * tag 'pm-4.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (112 commits) intel_pstate: Clean up get_target_pstate_use_performance() intel_pstate: Use sample.core_avg_perf in get_avg_pstate() intel_pstate: Clarify average performance computation intel_pstate: Avoid unnecessary synchronize_sched() during initialization cpufreq: schedutil: Make default depend on CONFIG_SMP cpufreq: powernv: del_timer_sync when global and local pstate are equal cpufreq: powernv: Move smp_call_function_any() out of irq safe block intel_pstate: Clean up intel_pstate_get() cpufreq: schedutil: Make it depend on CONFIG_SMP cpufreq: governor: Fix handling of special cases in dbs_update() PM / OPP: Move CONFIG_OF dependent code in a separate file cpufreq: intel_pstate: Ignore _PPC processing under HWP cpufreq: arm_big_little: use generic OPP functions for {init, free}_opp_table PM / OPP: add non-OF versions of dev_pm_opp_{cpumask_, }remove_table cpufreq: tango: Use generic platdev driver PM / OPP: pass cpumask by reference cpufreq: Fix GOV_LIMITS handling for the userspace governor cpupower: fix potential memory leak PM / devfreq: style/typo fixes PM / devfreq: exynos: Add the detailed correlation for Exynos5422 bus ..
2016-05-16Merge branch 'pm-cpufreq'Rafael J. Wysocki4-11/+576
* pm-cpufreq: (63 commits) intel_pstate: Clean up get_target_pstate_use_performance() intel_pstate: Use sample.core_avg_perf in get_avg_pstate() intel_pstate: Clarify average performance computation intel_pstate: Avoid unnecessary synchronize_sched() during initialization cpufreq: schedutil: Make default depend on CONFIG_SMP cpufreq: powernv: del_timer_sync when global and local pstate are equal cpufreq: powernv: Move smp_call_function_any() out of irq safe block intel_pstate: Clean up intel_pstate_get() cpufreq: schedutil: Make it depend on CONFIG_SMP cpufreq: governor: Fix handling of special cases in dbs_update() cpufreq: intel_pstate: Ignore _PPC processing under HWP cpufreq: arm_big_little: use generic OPP functions for {init, free}_opp_table cpufreq: tango: Use generic platdev driver cpufreq: Fix GOV_LIMITS handling for the userspace governor cpufreq: mvebu: Move cpufreq code into drivers/cpufreq/ cpufreq: dt: Kill platform-data mvebu: Use dev_pm_opp_set_sharing_cpus() to mark OPP tables as shared cpufreq: dt: Identify cpu-sharing for platforms without operating-points-v2 cpufreq: governor: Change confusing struct field and variable names cpufreq: intel_pstate: Enable PPC enforcement for servers ...
2016-05-12sched/core: Provide a tsk_nr_cpus_allowed() helperThomas Gleixner3-27/+27
tsk_nr_cpus_allowed() is an accessor for task->nr_cpus_allowed which allows us to change the representation of ->nr_cpus_allowed if required. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/1462969411-17735-2-git-send-email-bigeasy@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-05-12sched/core: Use tsk_cpus_allowed() instead of accessing ->cpus_allowedThomas Gleixner3-5/+5
Use the future-safe accessor for struct task_struct's. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/1462969411-17735-1-git-send-email-bigeasy@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-05-12sched/loadavg: Fix loadavg artifacts on fully idle and on fully loaded systemsVik Heyndrickx1-4/+7
Systems show a minimal load average of 0.00, 0.01, 0.05 even when they have no load at all. Uptime and /proc/loadavg on all systems with kernels released during the last five years up until kernel version 4.6-rc5, show a 5- and 15-minute minimum loadavg of 0.01 and 0.05 respectively. This should be 0.00 on idle systems, but the way the kernel calculates this value prevents it from getting lower than the mentioned values. Likewise but not as obviously noticeable, a fully loaded system with no processes waiting, shows a maximum 1/5/15 loadavg of 1.00, 0.99, 0.95 (multiplied by number of cores). Once the (old) load becomes 93 or higher, it mathematically can never get lower than 93, even when the active (load) remains 0 forever. This results in the strange 0.00, 0.01, 0.05 uptime values on idle systems. Note: 93/2048 = 0.0454..., which rounds up to 0.05. It is not correct to add a 0.5 rounding (=1024/2048) here, since the result from this function is fed back into the next iteration again, so the result of that +0.5 rounding value then gets multiplied by (2048-2037), and then rounded again, so there is a virtual "ghost" load created, next to the old and active load terms. By changing the way the internally kept value is rounded, that internal value equivalent now can reach 0.00 on idle, and 1.00 on full load. Upon increasing load, the internally kept load value is rounded up, when the load is decreasing, the load value is rounded down. The modified code was tested on nohz=off and nohz kernels. It was tested on vanilla kernel 4.6-rc5 and on centos 7.1 kernel 3.10.0-327. It was tested on single, dual, and octal cores system. It was tested on virtual hosts and bare hardware. No unwanted effects have been observed, and the problems that the patch intended to fix were indeed gone. Tested-by: Damien Wyart <damien.wyart@free.fr> Signed-off-by: Vik Heyndrickx <vik.heyndrickx@veribox.net> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: <stable@vger.kernel.org> Cc: Doug Smythies <dsmythies@telus.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: 0f004f5a696a ("sched: Cure more NO_HZ load average woes") Link: http://lkml.kernel.org/r/e8d32bff-d544-7748-72b5-3c86cc71f09f@veribox.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-05-12sched/fair: Correct unit of load_above_capacityMorten Rasmussen1-2/+4
In calculate_imbalance() load_above_capacity currently has the unit [capacity] while it is used as being [load/capacity]. Not only is it wrong it also makes it unlikely that load_above_capacity is ever used as the subsequent code picks the smaller of load_above_capacity and the avg_load This patch ensures that load_above_capacity has the right unit [load/capacity]. Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com> [ Changed changelog to note it was in capacity unit; +rebase. ] Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/1461958364-675-4-git-send-email-dietmar.eggemann@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-05-12sched/fair: Clean up scale confusionPeter Zijlstra1-2/+1
Wanpeng noted that the scale_load_down() in calculate_imbalance() was weird. I agree, it should be SCHED_CAPACITY_SCALE, since we're going to compare against busiest->group_capacity, which is in [capacity] units. Reported-by: Wanpeng Li <wanpeng.li@hotmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Morten Rasmussen <morten.rasmussen@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Yuyang Du <yuyang.du@intel.com> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-05-12sched/nohz: Fix affine unpinned timers messWanpeng Li1-1/+4
The following commit: 9642d18eee2c ("nohz: Affine unpinned timers to housekeepers")' intended to affine unpinned timers to housekeepers: unpinned timers(full dynaticks, idle) => nearest busy housekeepers(otherwise, fallback to any housekeepers) unpinned timers(full dynaticks, busy) => nearest busy housekeepers(otherwise, fallback to any housekeepers) unpinned timers(houserkeepers, idle) => nearest busy housekeepers(otherwise, fallback to itself) However, the !idle_cpu(i) && is_housekeeping_cpu(cpu) check modified the intention to: unpinned timers(full dynaticks, idle) => any housekeepers(no mattter cpu topology) unpinned timers(full dynaticks, busy) => any housekeepers(no mattter cpu topology) unpinned timers(housekeepers, idle) => any busy cpus(otherwise, fallback to any housekeepers) This patch fixes it by checking if there are busy housekeepers nearby, otherwise falls to any housekeepers/itself. After the patch: unpinned timers(full dynaticks, idle) => nearest busy housekeepers(otherwise, fallback to any housekeepers) unpinned timers(full dynaticks, busy) => nearest busy housekeepers(otherwise, fallback to any housekeepers) unpinned timers(housekeepers, idle) => nearest busy housekeepers(otherwise, fallback to itself) Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> [ Fixed the changelog. ] Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Fixes: 'commit 9642d18eee2c ("nohz: Affine unpinned timers to housekeepers")' Link: http://lkml.kernel.org/r/1462344334-8303-1-git-send-email-wanpeng.li@hotmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-05-12sched/fair: Fix fairness issue on migrationPeter Zijlstra1-6/+16
Pavan reported that in the presence of very light tasks (or cgroups) the placement of migrated tasks can cause severe fairness issues. The problem is that enqueue_entity() places the task before it updates time, thereby it can place the task far in the past (remember that light tasks will shoot virtual time forward at a high speed, so in relation to the pre-existing light task, we can land far in the past). This is done because update_curr() needs the current task, and we might be placing the current task. The obvious solution is to differentiate between the current and any other task; placing the current before we update time, and placing any other task after, such that !curr tasks end up at the current moment in time, and not in the past. This commit re-introduces the previously reverted commit: 3a47d5124a95 ("sched/fair: Fix fairness issue on migration") ... which is now safe to do, after we've also fixed another underlying bug first, in: sched/fair: Prepare to fix fairness problems on migration and cleaned up other details in the migration code: sched/core: Kill sched_class::task_waking Reported-by: Pavan Kondeti <pkondeti@codeaurora.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-05-12sched/core: Kill sched_class::task_waking to clean up the migration logicPeter Zijlstra3-42/+32
With sched_class::task_waking being called only when we do set_task_cpu(), we can make sched_class::migrate_task_rq() do the work and eliminate sched_class::task_waking entirely. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Hunter <ahh@google.com> Cc: Ben Segall <bsegall@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: Mike Galbraith <efault@gmx.de> Cc: Mike Galbraith <umgwanakikbuti@gmail.com> Cc: Morten Rasmussen <morten.rasmussen@arm.com> Cc: Paul Turner <pjt@google.com> Cc: Pavan Kondeti <pkondeti@codeaurora.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: byungchul.park@lge.com Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-05-12sched/fair: Prepare to fix fairness problems on migrationPeter Zijlstra2-8/+58
Mike reported that our recent attempt to fix migration problems: 3a47d5124a95 ("sched/fair: Fix fairness issue on migration") broke interactivity and the signal starve test. We reverted that commit and now let's try it again more carefully, with some other underlying problems fixed first. One problem is that I assumed ENQUEUE_WAKING was only set when we do a cross-cpu wakeup (migration), which isn't true. This means we now destroy the vruntime history of tasks and wakeup-preemption suffers. Cure this by making my assumption true, only call sched_class::task_waking() when we do a cross-cpu wakeup. This avoids the indirect call in the case we do a local wakeup. Reported-by: Mike Galbraith <mgalbraith@suse.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Hunter <ahh@google.com> Cc: Ben Segall <bsegall@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: Mike Galbraith <efault@gmx.de> Cc: Morten Rasmussen <morten.rasmussen@arm.com> Cc: Paul Turner <pjt@google.com> Cc: Pavan Kondeti <pkondeti@codeaurora.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: byungchul.park@lge.com Cc: linux-kernel@vger.kernel.org Fixes: 3a47d5124a95 ("sched/fair: Fix fairness issue on migration") Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-05-12sched/fair: Move record_wakee()Peter Zijlstra1-28/+33
Since I want to make ->task_woken() conditional on the task getting migrated, we cannot use it to call record_wakee(). Move it to select_task_rq_fair(), which gets called in almost all the same conditions. The only exception is if the woken task (@p) is CPU-bound (as per the nr_cpus_allowed test in select_task_rq()). Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Hunter <ahh@google.com> Cc: Ben Segall <bsegall@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: Mike Galbraith <efault@gmx.de> Cc: Mike Galbraith <umgwanakikbuti@gmail.com> Cc: Morten Rasmussen <morten.rasmussen@arm.com> Cc: Paul Turner <pjt@google.com> Cc: Pavan Kondeti <pkondeti@codeaurora.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: byungchul.park@lge.com Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-05-12Merge branch 'smp/hotplug' into sched/core, to resolve conflictsIngo Molnar3-238/+180
Conflicts: kernel/sched/core.c Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-05-12Merge branch 'sched/urgent' into sched/core to pick up fixesIngo Molnar3-15/+16
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-05-11Revert "sched/fair: Fix fairness issue on migration"Ingo Molnar1-14/+6
Mike reported that this recent commit: 3a47d5124a95 ("sched/fair: Fix fairness issue on migration") ... broke interactivity and the signal starvation test. We have a proper fix series in the works but ran out of time for v4.6, so revert the commit. Reported-by: Mike Galbraith <efault@gmx.de> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-05-10sched/rt, sched/dl: Don't push if task's scheduling class was changedXunlei Pang2-0/+2
We got this warning: WARNING: CPU: 1 PID: 2468 at kernel/sched/core.c:1161 set_task_cpu+0x1af/0x1c0 [...] Call Trace: dump_stack+0x63/0x87 __warn+0xd1/0xf0 warn_slowpath_null+0x1d/0x20 set_task_cpu+0x1af/0x1c0 push_dl_task.part.34+0xea/0x180 push_dl_tasks+0x17/0x30 __balance_callback+0x45/0x5c __sched_setscheduler+0x906/0xb90 SyS_sched_setattr+0x150/0x190 do_syscall_64+0x62/0x110 entry_SYSCALL64_slow_path+0x25/0x25 This corresponds to: WARN_ON_ONCE(p->state == TASK_RUNNING && p->sched_class == &fair_sched_class && (p->on_rq && !task_on_rq_migrating(p))) It happens because in find_lock_later_rq(), the task whose scheduling class was changed to fair class is still pushed away as if it were a deadline task ... So, check in find_lock_later_rq() after double_lock_balance(), if the scheduling class of the deadline task was changed, break and retry. Apply the same logic to RT tasks. Signed-off-by: Xunlei Pang <xlpang@redhat.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Juri Lelli <juri.lelli@arm.com> Link: http://lkml.kernel.org/r/1462767091-1215-1-git-send-email-xlpang@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-05-09sched/core: Fix comment typo in wake_q_add()Davidlohr Bueso1-1/+1
... the comment clearly refers to wake_up_q(), and not wake_up_list(). Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: dave@stgolabs.net Link: http://lkml.kernel.org/r/1462766290-28664-1-git-send-email-dave@stgolabs.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-05-09sched/core: Remove unused variableMuhammad Falak R Wani1-2/+2
Remove unused variable 'ret', and directly return 0. Signed-off-by: Muhammad Falak R Wani <falakreyaz@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1462441879-10092-1-git-send-email-falakreyaz@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-05-07sched/fair: Fix !CONFIG_SMP kernel cpufreq governor breakageRafael J. Wysocki1-1/+8
The following commit: 34e2c555f3e1 ("cpufreq: Add mechanism for registering utilization update callbacks") overlooked the fact that update_load_avg(), where CFS invokes cpufreq utilization update callbacks, becomes an empty stub on UP kernels. In consequence, if !CONFIG_SMP, cpufreq governors are never invoked from CFS and they do not have a chance to evaluate CPU performace levels and update them often enough. Needless to say, things don't work as expected then. Fix the problem by making the !CONFIG_SMP stub of update_load_avg() invoke cpufreq update callbacks too. Reported-by: Steve Muckle <steve.muckle@linaro.org> Tested-by: Steve Muckle <steve.muckle@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Steve Muckle <steve.muckle@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Linux PM list <linux-pm@vger.kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Viresh Kumar <viresh.kumar@linaro.org> Fixes: 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks) Link: http://lkml.kernel.org/r/6282396.VVEdgVYxO3@vostro.rjw.lan Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-05-06sched: Make hrtick_notifier an explicit callThomas Gleixner1-33/+1
No need for an extra notifier. We don't need to handle all these states. It's sufficient to kill the timer when the cpu dies. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160310120025.770528462@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-05-06sched/fair: Make ilb_notifier an explicit callThomas Gleixner3-14/+6
No need for an extra notifier. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160310120025.693720241@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-05-06sched/hotplug: Move migration CPU_DYING to sched_cpu_dying()Thomas Gleixner1-50/+22
Remove the hotplug notifier and make it an explicit state. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160310120025.502222097@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-05-06sched/migration: Move CPU_ONLINE into scheduler stateThomas Gleixner1-11/+22
The alleged requirement that the migration notifier has a lower priority than perf is completely undocumented and there is no indication at all that this is true. perf does not even handle the CPU_ONLINE notification and perf really has nothing to do with migration. Move the CPU_ONLINE code into the sched_activate_cpu() state callback. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160310120025.421743581@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-05-06sched/migration: Move calc_load_migrate() into CPU_DYINGThomas Gleixner1-3/+0
It really does not matter when we fold the load for the outgoing cpu. It's almost dead anyway, so there is no harm if we fail to fold the few microseconds which are required for going fully away. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160310120025.328739226@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-05-06sched/migration: Move prepare transition to SCHED_STARTING stateThomas Gleixner1-9/+11
We can piggy pack that on the SCHED_STARTING state. It's not required before the cpu actually comes online. Name the function proper as it has nothing to do with migration. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160310120025.248226511@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-05-06sched/hotplug: Move sync_rcu to be with set_cpu_active(false)Peter Zijlstra1-0/+14
The sync_rcu stuff is specificically for clearing bits in the active mask, such that everybody will observe the bit cleared and will not consider the cleared CPU for load-balancing etc. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160310120025.169219710@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-05-06sched/hotplug: Convert cpu_[in]active notifiers to state machineThomas Gleixner1-46/+21
Now that we reduced everything into single notifiers, it's simple to move them into the hotplug state machine space. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: rt@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-05-06sched: Move sched_domains_numa_masks_clear() to DOWN_PREPAREThomas Gleixner1-3/+0
This is the last operation on the cpu before vanishing. No point in calling that on CPU_DEAD. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: rt@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-05-06sched: Consolidate the notifier mazeThomas Gleixner1-105/+69
We can maintain the ordering of the scheduler cpu hotplug functionality nicely in one notifer. Get rid of the maze. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: rt@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-05-06sched: Allow hotplug notifiers to be setup earlyThomas Gleixner1-23/+36
Prevent the SMP scheduler related notifiers to be executed before the smp scheduler is initialized and install them early. This is a preparatory change for further consolidation of the hotplug notifier maze. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: rt@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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