Re: [PATCH V2] idle/intel_powerclamp: Redesign idle injection to use bandwidth control mechanism

From: Steven Noonan
Date: Mon Feb 09 2015 - 13:14:49 EST

On Mon, Feb 9, 2015 at 9:56 AM, Steven Noonan <steven@xxxxxxxxxxxxxx> wrote:
> On Mon, Feb 9, 2015 at 3:51 AM, Preeti U Murthy
> <preeti@xxxxxxxxxxxxxxxxxx> wrote:
>> Hi Steven,
>>
>> On 02/09/2015 01:02 PM, Steven Noonan wrote:
>>> On Sun, Feb 8, 2015 at 8:49 PM, Preeti U Murthy
>>> <preeti@xxxxxxxxxxxxxxxxxx> wrote:
>>>> The powerclamp driver injects idle periods to stay within the thermal constraints.
>>>> The driver does a fake idle by spawning per-cpu threads that call the mwait
>>>> instruction. This behavior of fake idle can confuse the other kernel subsystems.
>>>> For instance it calls into the nohz tick handlers, which are meant to be called
>>>> only by the idle thread. It sets the state of the tick in each cpu to idle and
>>>> stops the tick, when there are tasks on the runqueue. As a result the callers of
>>>> idle_cpu()/ tick_nohz_tick_stopped() see different states of the cpu; while the
>>>> former thinks that the cpu is busy, the latter thinks that it is idle. The outcome
>>>> may be inconsistency in the scheduler/nohz states which can lead to serious
>>>> consequences. One of them was reported on this thread:
>>>> https://lkml.org/lkml/2014/12/11/365.
>>>>
>>>> Thomas posted out a patch to disable the powerclamp driver from calling into the
>>>> tick nohz code which has taken care of the above regression for the moment. However
>>>> powerclamp driver as a result, will not be able to inject idle periods due to the
>>>> presence of periodic ticks. With the current design of fake idle, we cannot move
>>>> towards a better solution.
>>>> https://lkml.org/lkml/2014/12/18/169
>>>>
>>>> This patch aims at removing the concept of fake idle and instead makes the cpus
>>>> truly idle by throttling the runqueues during the idle injection periods. The situation
>>>> is in fact very similar to throttling of cfs_rqs when they exceed their bandwidths.
>>>> The idle injection metrics can be mapped to the bandwidth control metrics 'quota' and
>>>> 'period' to achieve the same result. When the powerclamping is begun or when the
>>>> clamping controls have been modified, the bandwidth for the root task group is set.
>>>> The 'quota' will be the amount of time that the system needs to be busy and 'period'
>>>> will be the sum of this busy duration and the idle duration as calculated by the driver.
>>>> This gets rid of per-cpu kthreads, control cpu, hotplug notifiers and clamping mask since
>>>> the thread starting powerclamping will set the bandwidth and throttling of all cpus will
>>>> automatically fall in place. None of the other cpus need be bothered about this. This
>>>> simplifies the design of the driver.
>>>>
>>>> Of course this is only if the idle injection metrics can be conveniently transformed
>>>> into bandwidth control metrics. There are a couple of other primary concerns around if
>>>> doing the below two in this patch is valid.
>>>> a. This patch exports the functions to set the quota and period of task groups.
>>>> b. This patch removes the constraint of not being able to set the root task grp's bandwidth.
>>>>
>>>> Signed-off-by: Preeti U Murthy <preeti@xxxxxxxxxxxxxxxxxx>
>>>
>>> This doesn't compile.
>>
>> Thanks for reporting this! I realized that I had not compiled in the powerclamp driver
>> as a module while compile testing it. I was focusing on the issues with the design and
>> failed to cross verify this. Apologies for the inconvenience.
>>
>> Find the diff compile tested below.
>>
>> I also realized that clamp_cpus() that sets the bandwidth cannot be called from
>> multiple places. Currently I am calling it from end_powerclamp(), when the user changes the
>> idle clamping duration and from a queued timer. This will require synchronization between
>> callers which is not really called for. The queued wakeup_timer alone can re-evaluate the
>> clamping metrics after every throttle-unthrottle period and this should suffice as far
>> as I can see. Thoughts ?
>
> Hmm, I've had two system lockups so far while running a kernel with
> intel_powerclamp loaded. Both times it slowly ground to a halt and
> processes piled up...

I let the hung system sit for a while and it eventually partially recovered and
came back with this in dmesg (9:24 is around system boot time, 9:51 is around
when it went out to lunch, and 10:01 is when it came back):

Feb 09 09:24:16 osprey kernel: wlp2s0: authenticate with e0:3f:49:28:3b:8c
Feb 09 09:24:16 osprey kernel: wlp2s0: send auth to e0:3f:49:28:3b:8c (try 1/3)
Feb 09 09:24:16 osprey kernel: wlp2s0: authenticated
Feb 09 09:24:16 osprey kernel: wlp2s0: associate with e0:3f:49:28:3b:8c (try 1/3)
Feb 09 09:24:16 osprey kernel: wlp2s0: RX AssocResp from e0:3f:49:28:3b:8c (capab=0x1011 status=0 aid=4)
Feb 09 09:24:16 osprey kernel: wlp2s0: associated
Feb 09 09:50:19 osprey kernel: intel_powerclamp: Start idle injection to reduce power
Feb 09 09:50:23 osprey kernel: intel_powerclamp: Stop forced idle injection
Feb 09 09:50:27 osprey kernel: intel_powerclamp: Start idle injection to reduce power
Feb 09 09:50:31 osprey kernel: intel_powerclamp: Stop forced idle injection
Feb 09 09:50:31 osprey kernel: intel_powerclamp: Start idle injection to reduce power
Feb 09 09:50:57 osprey kernel: Watchdog[1271]: segfault at 0 ip 00007f580734ad7b sp 00007f57f04175a0 error 6 in chromium[7f580310e000+66c6000]
Feb 09 09:51:46 osprey kernel: INFO: rcu_preempt self-detected stall on CPU
Feb 09 09:51:46 osprey kernel: 0: (1 GPs behind) idle=d1d/2/0 softirq=48032/48032 last_accelerate: a04e/8abc, nonlazy_posted: 0, L.
Feb 09 09:51:46 osprey kernel: (t=60000 jiffies g=40078 c=40077 q=69418)
Feb 09 09:51:46 osprey kernel: Task dump for CPU 0:
Feb 09 09:51:46 osprey kernel: swapper/0 R running task 0 0 0 0x00000008
Feb 09 09:51:46 osprey kernel: 0000000000000000 ffff88041ea03ae0 ffffffff81099946 0000000000000000
Feb 09 09:51:46 osprey kernel: ffffffff81a56f00 ffff88041ea03b00 ffffffff8109ce8d ffff88041ea0d300
Feb 09 09:51:46 osprey kernel: 0000000000000001 ffff88041ea03b30 ffffffff810cd391 ffff88041ea0d300
Feb 09 09:51:46 osprey kernel: Call Trace:
Feb 09 09:51:46 osprey kernel: <IRQ> [<ffffffff81099946>] sched_show_task+0xb6/0x120
Feb 09 09:51:46 osprey kernel: [<ffffffff8109ce8d>] dump_cpu_task+0x3d/0x50
Feb 09 09:51:46 osprey kernel: [<ffffffff810cd391>] rcu_dump_cpu_stacks+0x91/0xd0
Feb 09 09:51:46 osprey kernel: [<ffffffff810d15c2>] rcu_check_callbacks+0x4d2/0x7e0
Feb 09 09:51:46 osprey kernel: [<ffffffff812c6e73>] ? __this_cpu_preempt_check+0x13/0x20
Feb 09 09:51:46 osprey kernel: [<ffffffff810d7f46>] ? hrtimer_run_queues+0x36/0x110
Feb 09 09:51:46 osprey kernel: [<ffffffff810d68cb>] update_process_times+0x4b/0x80
Feb 09 09:51:46 osprey kernel: [<ffffffff810e5e65>] tick_sched_handle.isra.13+0x25/0x60
Feb 09 09:51:46 osprey kernel: [<ffffffff810e5ee5>] tick_sched_timer+0x45/0x80
Feb 09 09:51:46 osprey kernel: [<ffffffff810d6e87>] __run_hrtimer+0x77/0x250
Feb 09 09:51:46 osprey kernel: [<ffffffff810e5ea0>] ? tick_sched_handle.isra.13+0x60/0x60
Feb 09 09:51:46 osprey kernel: [<ffffffff810d79d7>] hrtimer_interrupt+0x107/0x250
Feb 09 09:51:46 osprey kernel: [<ffffffff8104acbb>] local_apic_timer_interrupt+0x3b/0x70
Feb 09 09:51:46 osprey kernel: [<ffffffff8152a8a3>] smp_apic_timer_interrupt+0x43/0x60
Feb 09 09:51:46 osprey kernel: [<ffffffff81528aed>] apic_timer_interrupt+0x6d/0x80
Feb 09 09:51:46 osprey kernel: [<ffffffffa0b0728b>] ? 0xffffffffa0b0728b
Feb 09 09:51:46 osprey kernel: [<ffffffffa0b0718d>] ? 0xffffffffa0b0718d
Feb 09 09:51:46 osprey kernel: [<ffffffffa0b075d0>] ? 0xffffffffa0b075d0
Feb 09 09:51:46 osprey kernel: [<ffffffffa0b075e5>] 0xffffffffa0b075e5
Feb 09 09:51:46 osprey kernel: [<ffffffff810d54ca>] call_timer_fn+0x3a/0x160
Feb 09 09:51:46 osprey kernel: [<ffffffffa0b075d0>] ? 0xffffffffa0b075d0
Feb 09 09:51:46 osprey kernel: [<ffffffff810d5dc4>] run_timer_softirq+0x264/0x310
Feb 09 09:51:46 osprey kernel: [<ffffffff81073ab6>] __do_softirq+0xf6/0x2e0
Feb 09 09:51:46 osprey kernel: [<ffffffff81073efe>] irq_exit+0x8e/0xb0
Feb 09 09:51:46 osprey kernel: [<ffffffff8152a8a8>] smp_apic_timer_interrupt+0x48/0x60
Feb 09 09:51:46 osprey kernel: [<ffffffff81528aed>] apic_timer_interrupt+0x6d/0x80
Feb 09 09:51:46 osprey kernel: <EOI> [<ffffffff813e5db5>] ? cpuidle_enter_state+0x65/0x1a0
Feb 09 09:51:46 osprey kernel: [<ffffffff813e5da1>] ? cpuidle_enter_state+0x51/0x1a0
Feb 09 09:51:46 osprey kernel: [<ffffffff813e5fd7>] cpuidle_enter+0x17/0x20
Feb 09 09:51:46 osprey kernel: [<ffffffff810af014>] cpu_startup_entry+0x3f4/0x460
Feb 09 09:51:46 osprey kernel: [<ffffffff815187f5>] rest_init+0x85/0x90
Feb 09 09:51:46 osprey kernel: [<ffffffff81ba0f7e>] start_kernel+0x445/0x452
Feb 09 09:51:46 osprey kernel: [<ffffffff81ba0120>] ? early_idt_handlers+0x120/0x120
Feb 09 09:51:46 osprey kernel: [<ffffffff81ba04d7>] x86_64_start_reservations+0x2a/0x2c
Feb 09 09:51:46 osprey kernel: [<ffffffff81ba061c>] x86_64_start_kernel+0x143/0x152
Feb 09 09:54:46 osprey kernel: INFO: rcu_preempt self-detected stall on CPU
Feb 09 09:54:46 osprey kernel: 0: (1 GPs behind) idle=d1d/2/0 softirq=48032/48032 last_accelerate: a04e/49df, nonlazy_posted: 0, L.
Feb 09 09:54:46 osprey kernel: (t=240003 jiffies g=40078 c=40077 q=72706)
Feb 09 09:54:46 osprey kernel: Task dump for CPU 0:
Feb 09 09:54:46 osprey kernel: swapper/0 R running task 0 0 0 0x00000008
Feb 09 09:54:46 osprey kernel: 0000000000000000 ffff88041ea03ae0 ffffffff81099946 0000000000000000
Feb 09 09:54:46 osprey kernel: ffffffff81a56f00 ffff88041ea03b00 ffffffff8109ce8d ffff88041ea0d300
Feb 09 09:54:46 osprey kernel: 0000000000000001 ffff88041ea03b30 ffffffff810cd391 ffff88041ea0d300
Feb 09 09:54:46 osprey kernel: Call Trace:
Feb 09 09:54:46 osprey kernel: <IRQ> [<ffffffff81099946>] sched_show_task+0xb6/0x120
Feb 09 09:54:46 osprey kernel: [<ffffffff8109ce8d>] dump_cpu_task+0x3d/0x50
Feb 09 09:54:46 osprey kernel: [<ffffffff810cd391>] rcu_dump_cpu_stacks+0x91/0xd0
Feb 09 09:54:46 osprey kernel: [<ffffffff810d15c2>] rcu_check_callbacks+0x4d2/0x7e0
Feb 09 09:54:46 osprey kernel: [<ffffffff812c6e73>] ? __this_cpu_preempt_check+0x13/0x20
Feb 09 09:54:46 osprey kernel: [<ffffffff810d7f46>] ? hrtimer_run_queues+0x36/0x110
Feb 09 09:54:46 osprey kernel: [<ffffffff810d68cb>] update_process_times+0x4b/0x80
Feb 09 09:54:46 osprey kernel: [<ffffffff810e5e65>] tick_sched_handle.isra.13+0x25/0x60
Feb 09 09:54:46 osprey kernel: [<ffffffff810e5ee5>] tick_sched_timer+0x45/0x80
Feb 09 09:54:46 osprey kernel: [<ffffffff810d6e87>] __run_hrtimer+0x77/0x250
Feb 09 09:54:46 osprey kernel: [<ffffffff810e5ea0>] ? tick_sched_handle.isra.13+0x60/0x60
Feb 09 09:54:46 osprey kernel: [<ffffffff810d79d7>] hrtimer_interrupt+0x107/0x250
Feb 09 09:54:46 osprey kernel: [<ffffffff8104acbb>] local_apic_timer_interrupt+0x3b/0x70
Feb 09 09:54:46 osprey kernel: [<ffffffff8152a8a3>] smp_apic_timer_interrupt+0x43/0x60
Feb 09 09:54:46 osprey kernel: [<ffffffff81528aed>] apic_timer_interrupt+0x6d/0x80
Feb 09 09:54:46 osprey kernel: [<ffffffffa0b0726d>] ? 0xffffffffa0b0726d
Feb 09 09:54:46 osprey kernel: [<ffffffffa0b0718d>] ? 0xffffffffa0b0718d
Feb 09 09:54:46 osprey kernel: [<ffffffffa0b075d0>] ? 0xffffffffa0b075d0
Feb 09 09:54:46 osprey kernel: [<ffffffffa0b075e5>] 0xffffffffa0b075e5
Feb 09 09:54:46 osprey kernel: [<ffffffff810d54ca>] call_timer_fn+0x3a/0x160
Feb 09 09:54:46 osprey kernel: [<ffffffffa0b075d0>] ? 0xffffffffa0b075d0
Feb 09 09:54:46 osprey kernel: [<ffffffff810d5dc4>] run_timer_softirq+0x264/0x310
Feb 09 09:54:46 osprey kernel: [<ffffffff81073ab6>] __do_softirq+0xf6/0x2e0
Feb 09 09:54:46 osprey kernel: [<ffffffff81073efe>] irq_exit+0x8e/0xb0
Feb 09 09:54:46 osprey kernel: [<ffffffff8152a8a8>] smp_apic_timer_interrupt+0x48/0x60
Feb 09 09:54:46 osprey kernel: [<ffffffff81528aed>] apic_timer_interrupt+0x6d/0x80
Feb 09 09:54:46 osprey kernel: <EOI> [<ffffffff813e5db5>] ? cpuidle_enter_state+0x65/0x1a0
Feb 09 09:54:46 osprey kernel: [<ffffffff813e5da1>] ? cpuidle_enter_state+0x51/0x1a0
Feb 09 09:54:46 osprey kernel: [<ffffffff813e5fd7>] cpuidle_enter+0x17/0x20
Feb 09 09:54:46 osprey kernel: [<ffffffff810af014>] cpu_startup_entry+0x3f4/0x460
Feb 09 09:54:46 osprey kernel: [<ffffffff815187f5>] rest_init+0x85/0x90
Feb 09 09:54:46 osprey kernel: [<ffffffff81ba0f7e>] start_kernel+0x445/0x452
Feb 09 09:54:46 osprey kernel: [<ffffffff81ba0120>] ? early_idt_handlers+0x120/0x120
Feb 09 09:54:46 osprey kernel: [<ffffffff81ba04d7>] x86_64_start_reservations+0x2a/0x2c
Feb 09 09:54:46 osprey kernel: [<ffffffff81ba061c>] x86_64_start_kernel+0x143/0x152
Feb 09 09:57:46 osprey kernel: INFO: rcu_preempt self-detected stall on CPU
Feb 09 09:57:46 osprey kernel: 0: (1 GPs behind) idle=d1d/2/0 softirq=48032/48032 last_accelerate: a04e/0902, nonlazy_posted: 0, L.
Feb 09 09:57:46 osprey kernel: (t=420006 jiffies g=40078 c=40077 q=76104)
Feb 09 09:57:46 osprey kernel: Task dump for CPU 0:
Feb 09 09:57:46 osprey kernel: swapper/0 R running task 0 0 0 0x00000008
Feb 09 09:57:46 osprey kernel: 0000000000000000 ffff88041ea03ae0 ffffffff81099946 0000000000000000
Feb 09 09:57:46 osprey kernel: ffffffff81a56f00 ffff88041ea03b00 ffffffff8109ce8d ffff88041ea0d300
Feb 09 09:57:46 osprey kernel: 0000000000000001 ffff88041ea03b30 ffffffff810cd391 ffff88041ea0d300
Feb 09 09:57:46 osprey kernel: Call Trace:
Feb 09 09:57:46 osprey kernel: <IRQ> [<ffffffff81099946>] sched_show_task+0xb6/0x120
Feb 09 09:57:46 osprey kernel: [<ffffffff8109ce8d>] dump_cpu_task+0x3d/0x50
Feb 09 09:57:46 osprey kernel: [<ffffffff810cd391>] rcu_dump_cpu_stacks+0x91/0xd0
Feb 09 09:57:46 osprey kernel: [<ffffffff810d15c2>] rcu_check_callbacks+0x4d2/0x7e0
Feb 09 09:57:46 osprey kernel: [<ffffffff812c6e73>] ? __this_cpu_preempt_check+0x13/0x20
Feb 09 09:57:46 osprey kernel: [<ffffffff810d7f46>] ? hrtimer_run_queues+0x36/0x110
Feb 09 09:57:46 osprey kernel: [<ffffffff810d68cb>] update_process_times+0x4b/0x80
Feb 09 09:57:46 osprey kernel: [<ffffffff810e5e65>] tick_sched_handle.isra.13+0x25/0x60
Feb 09 09:57:46 osprey kernel: [<ffffffff810e5ee5>] tick_sched_timer+0x45/0x80
Feb 09 09:57:46 osprey kernel: [<ffffffff810d6e87>] __run_hrtimer+0x77/0x250
Feb 09 09:57:46 osprey kernel: [<ffffffff810e5ea0>] ? tick_sched_handle.isra.13+0x60/0x60
Feb 09 09:57:46 osprey kernel: [<ffffffff810d79d7>] hrtimer_interrupt+0x107/0x250
Feb 09 09:57:46 osprey kernel: [<ffffffff8104acbb>] local_apic_timer_interrupt+0x3b/0x70
Feb 09 09:57:46 osprey kernel: [<ffffffff8152a8a3>] smp_apic_timer_interrupt+0x43/0x60
Feb 09 09:57:46 osprey kernel: [<ffffffff81528aed>] apic_timer_interrupt+0x6d/0x80
Feb 09 09:57:46 osprey kernel: [<ffffffffa0b0726d>] ? 0xffffffffa0b0726d
Feb 09 09:57:46 osprey kernel: [<ffffffffa0b0718d>] ? 0xffffffffa0b0718d
Feb 09 09:57:46 osprey kernel: [<ffffffffa0b075d0>] ? 0xffffffffa0b075d0
Feb 09 09:57:46 osprey kernel: [<ffffffffa0b075e5>] 0xffffffffa0b075e5
Feb 09 09:57:46 osprey kernel: [<ffffffff810d54ca>] call_timer_fn+0x3a/0x160
Feb 09 09:57:46 osprey kernel: [<ffffffffa0b075d0>] ? 0xffffffffa0b075d0
Feb 09 09:57:46 osprey kernel: [<ffffffff810d5dc4>] run_timer_softirq+0x264/0x310
Feb 09 09:57:46 osprey kernel: [<ffffffff81073ab6>] __do_softirq+0xf6/0x2e0
Feb 09 09:57:46 osprey kernel: [<ffffffff81073efe>] irq_exit+0x8e/0xb0
Feb 09 09:57:46 osprey kernel: [<ffffffff8152a8a8>] smp_apic_timer_interrupt+0x48/0x60
Feb 09 09:57:46 osprey kernel: [<ffffffff81528aed>] apic_timer_interrupt+0x6d/0x80
Feb 09 09:57:46 osprey kernel: <EOI> [<ffffffff813e5db5>] ? cpuidle_enter_state+0x65/0x1a0
Feb 09 09:57:46 osprey kernel: [<ffffffff813e5da1>] ? cpuidle_enter_state+0x51/0x1a0
Feb 09 09:57:46 osprey kernel: [<ffffffff813e5fd7>] cpuidle_enter+0x17/0x20
Feb 09 09:57:46 osprey kernel: [<ffffffff810af014>] cpu_startup_entry+0x3f4/0x460
Feb 09 09:57:46 osprey kernel: [<ffffffff815187f5>] rest_init+0x85/0x90
Feb 09 09:57:46 osprey kernel: [<ffffffff81ba0f7e>] start_kernel+0x445/0x452
Feb 09 09:57:46 osprey kernel: [<ffffffff81ba0120>] ? early_idt_handlers+0x120/0x120
Feb 09 09:57:46 osprey kernel: [<ffffffff81ba04d7>] x86_64_start_reservations+0x2a/0x2c
Feb 09 09:57:46 osprey kernel: [<ffffffff81ba061c>] x86_64_start_kernel+0x143/0x152
Feb 09 10:00:46 osprey kernel: INFO: rcu_preempt self-detected stall on CPU
Feb 09 10:00:46 osprey kernel: 0: (1 GPs behind) idle=d1d/2/0 softirq=48032/48032 last_accelerate: a04e/c825, nonlazy_posted: 0, L.
Feb 09 10:00:46 osprey kernel: (t=600009 jiffies g=40078 c=40077 q=79433)
Feb 09 10:00:46 osprey kernel: Task dump for CPU 0:
Feb 09 10:00:46 osprey kernel: swapper/0 R running task 0 0 0 0x00000008
Feb 09 10:00:46 osprey kernel: 0000000000000000 ffff88041ea03ae0 ffffffff81099946 0000000000000000
Feb 09 10:00:46 osprey kernel: ffffffff81a56f00 ffff88041ea03b00 ffffffff8109ce8d ffff88041ea0d300
Feb 09 10:00:46 osprey kernel: 0000000000000001 ffff88041ea03b30 ffffffff810cd391 ffff88041ea0d300
Feb 09 10:00:46 osprey kernel: Call Trace:
Feb 09 10:00:46 osprey kernel: <IRQ> [<ffffffff81099946>] sched_show_task+0xb6/0x120
Feb 09 10:00:46 osprey kernel: [<ffffffff8109ce8d>] dump_cpu_task+0x3d/0x50
Feb 09 10:00:46 osprey kernel: [<ffffffff810cd391>] rcu_dump_cpu_stacks+0x91/0xd0
Feb 09 10:00:46 osprey kernel: [<ffffffff810d15c2>] rcu_check_callbacks+0x4d2/0x7e0
Feb 09 10:00:46 osprey kernel: [<ffffffff812c6e73>] ? __this_cpu_preempt_check+0x13/0x20
Feb 09 10:00:46 osprey kernel: [<ffffffff810d7f46>] ? hrtimer_run_queues+0x36/0x110
Feb 09 10:00:46 osprey kernel: [<ffffffff810d68cb>] update_process_times+0x4b/0x80
Feb 09 10:00:46 osprey kernel: [<ffffffff810e5e65>] tick_sched_handle.isra.13+0x25/0x60
Feb 09 10:00:46 osprey kernel: [<ffffffff810e5ee5>] tick_sched_timer+0x45/0x80
Feb 09 10:00:46 osprey kernel: [<ffffffff810d6e87>] __run_hrtimer+0x77/0x250
Feb 09 10:00:46 osprey kernel: [<ffffffff810e5ea0>] ? tick_sched_handle.isra.13+0x60/0x60
Feb 09 10:00:46 osprey kernel: [<ffffffff810d79d7>] hrtimer_interrupt+0x107/0x250
Feb 09 10:00:46 osprey kernel: [<ffffffff8104acbb>] local_apic_timer_interrupt+0x3b/0x70
Feb 09 10:00:46 osprey kernel: [<ffffffff8152a8a3>] smp_apic_timer_interrupt+0x43/0x60
Feb 09 10:00:46 osprey kernel: [<ffffffff81528aed>] apic_timer_interrupt+0x6d/0x80
Feb 09 10:00:46 osprey kernel: [<ffffffffa0b0726d>] ? 0xffffffffa0b0726d
Feb 09 10:00:46 osprey kernel: [<ffffffffa0b0718d>] ? 0xffffffffa0b0718d
Feb 09 10:00:46 osprey kernel: [<ffffffffa0b075d0>] ? 0xffffffffa0b075d0
Feb 09 10:00:46 osprey kernel: [<ffffffffa0b075e5>] 0xffffffffa0b075e5
Feb 09 10:00:46 osprey kernel: [<ffffffff810d54ca>] call_timer_fn+0x3a/0x160
Feb 09 10:00:46 osprey kernel: [<ffffffffa0b075d0>] ? 0xffffffffa0b075d0
Feb 09 10:00:46 osprey kernel: [<ffffffff810d5dc4>] run_timer_softirq+0x264/0x310
Feb 09 10:00:46 osprey kernel: [<ffffffff81073ab6>] __do_softirq+0xf6/0x2e0
Feb 09 10:00:46 osprey kernel: [<ffffffff81073efe>] irq_exit+0x8e/0xb0
Feb 09 10:00:46 osprey kernel: [<ffffffff8152a8a8>] smp_apic_timer_interrupt+0x48/0x60
Feb 09 10:00:46 osprey kernel: [<ffffffff81528aed>] apic_timer_interrupt+0x6d/0x80
Feb 09 10:00:46 osprey kernel: <EOI> [<ffffffff813e5db5>] ? cpuidle_enter_state+0x65/0x1a0
Feb 09 10:00:46 osprey kernel: [<ffffffff813e5da1>] ? cpuidle_enter_state+0x51/0x1a0
Feb 09 10:00:46 osprey kernel: [<ffffffff813e5fd7>] cpuidle_enter+0x17/0x20
Feb 09 10:00:46 osprey kernel: [<ffffffff810af014>] cpu_startup_entry+0x3f4/0x460
Feb 09 10:00:46 osprey kernel: [<ffffffff815187f5>] rest_init+0x85/0x90
Feb 09 10:00:46 osprey kernel: [<ffffffff81ba0f7e>] start_kernel+0x445/0x452
Feb 09 10:00:46 osprey kernel: [<ffffffff81ba0120>] ? early_idt_handlers+0x120/0x120
Feb 09 10:00:46 osprey kernel: [<ffffffff81ba04d7>] x86_64_start_reservations+0x2a/0x2c
Feb 09 10:00:46 osprey kernel: [<ffffffff81ba061c>] x86_64_start_kernel+0x143/0x152

I couldn't do much at this point. While I had some interactivity, processes
were failing to spawn, so i had to just 'echo s > /proc/sysrq-trigger; echo b >
/proc/sysrq-trigger'.

>> ----------------------------------------------------------------------------------
>>
>> V2 of intel_powerclamp driver
>>
>> From: Preeti U Murthy <preeti@xxxxxxxxxxxxxxxxxx>
>>
>>
>> ---
>> drivers/thermal/Kconfig | 1
>> drivers/thermal/intel_powerclamp.c | 301 ++++++++++--------------------------
>> include/linux/sched.h | 9 +
>> kernel/sched/core.c | 6 -
>> kernel/sched/sched.h | 5 -
>> 5 files changed, 95 insertions(+), 227 deletions(-)
>>
>> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
>> index af40db0..4b7cd02 100644
>> --- a/drivers/thermal/Kconfig
>> +++ b/drivers/thermal/Kconfig
>> @@ -233,6 +233,7 @@ config INTEL_POWERCLAMP
>> depends on THERMAL
>> depends on X86
>> depends on CPU_SUP_INTEL
>> + select CFS_BANDWIDTH
>> help
>> Enable this to enable Intel PowerClamp idle injection driver. This
>> enforce idle time which results in more package C-state residency. The
>> diff --git a/drivers/thermal/intel_powerclamp.c b/drivers/thermal/intel_powerclamp.c
>> index 6ceebd6..4bd07bb 100644
>> --- a/drivers/thermal/intel_powerclamp.c
>> +++ b/drivers/thermal/intel_powerclamp.c
>> @@ -51,6 +51,7 @@
>> #include <linux/debugfs.h>
>> #include <linux/seq_file.h>
>> #include <linux/sched/rt.h>
>> +#include <linux/sched.h>
>>
>> #include <asm/nmi.h>
>> #include <asm/msr.h>
>> @@ -78,20 +79,18 @@ static struct dentry *debug_dir;
>> static unsigned int set_target_ratio;
>> static unsigned int current_ratio;
>> static bool should_skip;
>> +static unsigned int count = 0;
>> static bool reduce_irq;
>> static atomic_t idle_wakeup_counter;
>> -static unsigned int control_cpu; /* The cpu assigned to collect stat and update
>> - * control parameters. default to BSP but BSP
>> - * can be offlined.
>> - */
>> static bool clamping;
>>
>> +/* Timer that evaluates bandwidth reset if clamping knobs have changed */
>> +static void clamp_timer_fn(unsigned long foo);
>> +DEFINE_TIMER(wakeup_timer, clamp_timer_fn, 0, 0);
>> +
>> +static void clamp_cpus(void);
>>
>> -static struct task_struct * __percpu *powerclamp_thread;
>> static struct thermal_cooling_device *cooling_dev;
>> -static unsigned long *cpu_clamping_mask; /* bit map for tracking per cpu
>> - * clamping thread
>> - */
>>
>> static unsigned int duration;
>> static unsigned int pkg_cstate_ratio_cur;
>> @@ -163,7 +162,7 @@ static int window_size_set(const char *arg, const struct kernel_param *kp)
>> smp_mb();
>>
>> exit_win:
>> -
>> + clamp_cpus();
>> return ret;
>> }
>>
>> @@ -256,10 +255,6 @@ static u64 pkg_state_counter(void)
>> return count;
>> }
>>
>> -static void noop_timer(unsigned long foo)
>> -{
>> - /* empty... just the fact that we get the interrupt wakes us up */
>> -}
>>
>> static unsigned int get_compensation(int ratio)
>> {
>> @@ -362,100 +357,77 @@ static bool powerclamp_adjust_controls(unsigned int target_ratio,
>> return set_target_ratio + guard <= current_ratio;
>> }
>>
>> -static int clamp_thread(void *arg)
>> +static void clamp_cpus(void)
>> {
>> - int cpunr = (unsigned long)arg;
>> - DEFINE_TIMER(wakeup_timer, noop_timer, 0, 0);
>> - static const struct sched_param param = {
>> - .sched_priority = MAX_USER_RT_PRIO/2,
>> - };
>> - unsigned int count = 0;
>> unsigned int target_ratio;
>> + u64 quota, period;
>> + int sleeptime;
>> + unsigned long target_jiffies;
>> + unsigned int guard;
>> + unsigned int compensation;
>> + int interval; /* jiffies to sleep for each attempt */
>> + unsigned int duration_jiffies;
>> + unsigned int window_size_now;
>> +
>> +again:
>> + if (clamping == false)
>> + goto out;
>> +
>> + quota = RUNTIME_INF;
>> + period = NSEC_PER_SEC;
>> + compensation = 0;
>> + duration_jiffies = msecs_to_jiffies(duration);
>> + /*
>> + * make sure user selected ratio does not take effect until
>> + * the next round. adjust target_ratio if user has changed
>> + * target such that we can converge quickly.
>> + */
>> + target_ratio = set_target_ratio;
>> + guard = 1 + target_ratio/20;
>> + window_size_now = window_size;
>>
>> - set_bit(cpunr, cpu_clamping_mask);
>> - set_freezable();
>> - init_timer_on_stack(&wakeup_timer);
>> - sched_setscheduler(current, SCHED_FIFO, &param);
>> -
>> - while (true == clamping && !kthread_should_stop() &&
>> - cpu_online(cpunr)) {
>> - int sleeptime;
>> - unsigned long target_jiffies;
>> - unsigned int guard;
>> - unsigned int compensation = 0;
>> - int interval; /* jiffies to sleep for each attempt */
>> - unsigned int duration_jiffies = msecs_to_jiffies(duration);
>> - unsigned int window_size_now;
>> -
>> - try_to_freeze();
>> - /*
>> - * make sure user selected ratio does not take effect until
>> - * the next round. adjust target_ratio if user has changed
>> - * target such that we can converge quickly.
>> - */
>> - target_ratio = set_target_ratio;
>> - guard = 1 + target_ratio/20;
>> - window_size_now = window_size;
>> - count++;
>> -
>> - /*
>> - * systems may have different ability to enter package level
>> - * c-states, thus we need to compensate the injected idle ratio
>> - * to achieve the actual target reported by the HW.
>> - */
>> - compensation = get_compensation(target_ratio);
>> - interval = duration_jiffies*100/(target_ratio+compensation);
>> -
>> - /* align idle time */
>> - target_jiffies = roundup(jiffies, interval);
>> - sleeptime = target_jiffies - jiffies;
>> - if (sleeptime <= 0)
>> - sleeptime = 1;
>> - schedule_timeout_interruptible(sleeptime);
>> - /*
>> - * only elected controlling cpu can collect stats and update
>> - * control parameters.
>> - */
>> - if (cpunr == control_cpu && !(count%window_size_now)) {
>> - should_skip =
>> - powerclamp_adjust_controls(target_ratio,
>> - guard, window_size_now);
>> - smp_mb();
>> - }
>> -
>> - if (should_skip)
>> - continue;
>> -
>> - target_jiffies = jiffies + duration_jiffies;
>> - mod_timer(&wakeup_timer, target_jiffies);
>> - if (unlikely(local_softirq_pending()))
>> - continue;
>> - /*
>> - * stop tick sched during idle time, interrupts are still
>> - * allowed. thus jiffies are updated properly.
>> - */
>> - preempt_disable();
>> - /* mwait until target jiffies is reached */
>> - while (time_before(jiffies, target_jiffies)) {
>> - unsigned long ecx = 1;
>> - unsigned long eax = target_mwait;
>> -
>> - /*
>> - * REVISIT: may call enter_idle() to notify drivers who
>> - * can save power during cpu idle. same for exit_idle()
>> - */
>> - local_touch_nmi();
>> - stop_critical_timings();
>> - mwait_idle_with_hints(eax, ecx);
>> - start_critical_timings();
>> - atomic_inc(&idle_wakeup_counter);
>> - }
>> - preempt_enable();
>> + /*
>> + * systems may have different ability to enter package level
>> + * c-states, thus we need to compensate the injected idle ratio
>> + * to achieve the actual target reported by the HW.
>> + */
>> + compensation = get_compensation(target_ratio);
>> + interval = duration_jiffies*100/(target_ratio+compensation);
>> +
>> + /* align idle time */
>> + target_jiffies = roundup(jiffies, interval);
>> + sleeptime = target_jiffies - jiffies;
>> + if (sleeptime <= 0)
>> + sleeptime = 1;
>> +
>> + if (!(count%window_size_now)) {
>> + should_skip =
>> + powerclamp_adjust_controls(target_ratio,
>> + guard, window_size_now);
>> + smp_mb();
>> }
>> - del_timer_sync(&wakeup_timer);
>> - clear_bit(cpunr, cpu_clamping_mask);
>>
>> - return 0;
>> + if (should_skip)
>> + goto again;
>> +
>> + target_jiffies = jiffies + sleeptime + duration_jiffies;
>> + mod_timer(&wakeup_timer, target_jiffies);
>> + if (unlikely(local_softirq_pending()))
>> + goto again;
>> +
>> + quota = jiffies_to_usecs(sleeptime);
>> + period = jiffies_to_usecs(sleeptime + duration_jiffies);
>> +
>> +out:
>> + tg_set_cfs_quota(&root_task_group, quota);
>> + tg_set_cfs_period(&root_task_group, period);
>> +}
>> +
>> +static void clamp_timer_fn(unsigned long foo)
>> +{
>> + /* Evaluate to see if clamping controls need to be adjusted */
>> + count++;
>> + clamp_cpus();
>> }
>>
>> /*
>> @@ -501,8 +473,7 @@ static void poll_pkg_cstate(struct work_struct *dummy)
>>
>> static int start_power_clamp(void)
>> {
>> - unsigned long cpu;
>> - struct task_struct *thread;
>> + clamping = true;
>>
>> /* check if pkg cstate counter is completely 0, abort in this case */
>> if (!has_pkg_state_counter()) {
>> @@ -511,108 +482,21 @@ static int start_power_clamp(void)
>> }
>>
>> set_target_ratio = clamp(set_target_ratio, 0U, MAX_TARGET_RATIO - 1);
>> - /* prevent cpu hotplug */
>> - get_online_cpus();
>> -
>> - /* prefer BSP */
>> - control_cpu = 0;
>> - if (!cpu_online(control_cpu))
>> - control_cpu = smp_processor_id();
>>
>> - clamping = true;
>> schedule_delayed_work(&poll_pkg_cstate_work, 0);
>> -
>> - /* start one thread per online cpu */
>> - for_each_online_cpu(cpu) {
>> - struct task_struct **p =
>> - per_cpu_ptr(powerclamp_thread, cpu);
>> -
>> - thread = kthread_create_on_node(clamp_thread,
>> - (void *) cpu,
>> - cpu_to_node(cpu),
>> - "kidle_inject/%ld", cpu);
>> - /* bind to cpu here */
>> - if (likely(!IS_ERR(thread))) {
>> - kthread_bind(thread, cpu);
>> - wake_up_process(thread);
>> - *p = thread;
>> - }
>> -
>> - }
>> - put_online_cpus();
>> + clamp_cpus();
>>
>> return 0;
>> }
>>
>> static void end_power_clamp(void)
>> {
>> - int i;
>> - struct task_struct *thread;
>> -
>> clamping = false;
>> - /*
>> - * make clamping visible to other cpus and give per cpu clamping threads
>> - * sometime to exit, or gets killed later.
>> - */
>> - smp_mb();
>> - msleep(20);
>> - if (bitmap_weight(cpu_clamping_mask, num_possible_cpus())) {
>> - for_each_set_bit(i, cpu_clamping_mask, num_possible_cpus()) {
>> - pr_debug("clamping thread for cpu %d alive, kill\n", i);
>> - thread = *per_cpu_ptr(powerclamp_thread, i);
>> - kthread_stop(thread);
>> - }
>> - }
>> -}
>>
>> -static int powerclamp_cpu_callback(struct notifier_block *nfb,
>> - unsigned long action, void *hcpu)
>> -{
>> - unsigned long cpu = (unsigned long)hcpu;
>> - struct task_struct *thread;
>> - struct task_struct **percpu_thread =
>> - per_cpu_ptr(powerclamp_thread, cpu);
>> -
>> - if (false == clamping)
>> - goto exit_ok;
>> -
>> - switch (action) {
>> - case CPU_ONLINE:
>> - thread = kthread_create_on_node(clamp_thread,
>> - (void *) cpu,
>> - cpu_to_node(cpu),
>> - "kidle_inject/%lu", cpu);
>> - if (likely(!IS_ERR(thread))) {
>> - kthread_bind(thread, cpu);
>> - wake_up_process(thread);
>> - *percpu_thread = thread;
>> - }
>> - /* prefer BSP as controlling CPU */
>> - if (cpu == 0) {
>> - control_cpu = 0;
>> - smp_mb();
>> - }
>> - break;
>> - case CPU_DEAD:
>> - if (test_bit(cpu, cpu_clamping_mask)) {
>> - pr_err("cpu %lu dead but powerclamping thread is not\n",
>> - cpu);
>> - kthread_stop(*percpu_thread);
>> - }
>> - if (cpu == control_cpu) {
>> - control_cpu = smp_processor_id();
>> - smp_mb();
>> - }
>> - }
>> -
>> -exit_ok:
>> - return NOTIFY_OK;
>> + clamp_cpus();
>> + del_timer_sync(&wakeup_timer);
>> }
>>
>> -static struct notifier_block powerclamp_cpu_notifier = {
>> - .notifier_call = powerclamp_cpu_callback,
>> -};
>> -
>> static int powerclamp_get_max_state(struct thermal_cooling_device *cdev,
>> unsigned long *state)
>> {
>> @@ -656,6 +540,7 @@ static int powerclamp_set_cur_state(struct thermal_cooling_device *cdev,
>> }
>>
>> exit_set:
>> + clamp_cpus();
>> return ret;
>> }
>>
>> @@ -716,7 +601,6 @@ static int powerclamp_debug_show(struct seq_file *m, void *unused)
>> {
>> int i = 0;
>>
>> - seq_printf(m, "controlling cpu: %d\n", control_cpu);
>> seq_printf(m, "pct confidence steady dynamic (compensation)\n");
>> for (i = 0; i < MAX_TARGET_RATIO; i++) {
>> seq_printf(m, "%d\t%lu\t%lu\t%lu\n",
>> @@ -762,33 +646,20 @@ file_error:
>> static int powerclamp_init(void)
>> {
>> int retval;
>> - int bitmap_size;
>> -
>> - bitmap_size = BITS_TO_LONGS(num_possible_cpus()) * sizeof(long);
>> - cpu_clamping_mask = kzalloc(bitmap_size, GFP_KERNEL);
>> - if (!cpu_clamping_mask)
>> - return -ENOMEM;
>>
>> /* probe cpu features and ids here */
>> retval = powerclamp_probe();
>> if (retval)
>> - goto exit_free;
>> + goto exit;
>>
>> /* set default limit, maybe adjusted during runtime based on feedback */
>> window_size = 2;
>> - register_hotcpu_notifier(&powerclamp_cpu_notifier);
>> -
>> - powerclamp_thread = alloc_percpu(struct task_struct *);
>> - if (!powerclamp_thread) {
>> - retval = -ENOMEM;
>> - goto exit_unregister;
>> - }
>>
>> cooling_dev = thermal_cooling_device_register("intel_powerclamp", NULL,
>> &powerclamp_cooling_ops);
>> if (IS_ERR(cooling_dev)) {
>> retval = -ENODEV;
>> - goto exit_free_thread;
>> + goto exit;
>> }
>>
>> if (!duration)
>> @@ -798,23 +669,15 @@ static int powerclamp_init(void)
>>
>> return 0;
>>
>> -exit_free_thread:
>> - free_percpu(powerclamp_thread);
>> -exit_unregister:
>> - unregister_hotcpu_notifier(&powerclamp_cpu_notifier);
>> -exit_free:
>> - kfree(cpu_clamping_mask);
>> +exit:
>> return retval;
>> }
>> module_init(powerclamp_init);
>>
>> static void powerclamp_exit(void)
>> {
>> - unregister_hotcpu_notifier(&powerclamp_cpu_notifier);
>> end_power_clamp();
>> - free_percpu(powerclamp_thread);
>> thermal_cooling_device_unregister(cooling_dev);
>> - kfree(cpu_clamping_mask);
>>
>> cancel_delayed_work_sync(&poll_pkg_cstate_work);
>> debugfs_remove_recursive(debug_dir);
>> diff --git a/include/linux/sched.h b/include/linux/sched.h
>> index 8db31ef..2493942 100644
>> --- a/include/linux/sched.h
>> +++ b/include/linux/sched.h
>> @@ -163,6 +163,11 @@ extern void get_avenrun(unsigned long *loads, unsigned long offset, int shift);
>> load += n*(FIXED_1-exp); \
>> load >>= FSHIFT;
>>
>> +/*
>> + * single value that denotes runtime == period, ie unlimited time.
>> + */
>> +#define RUNTIME_INF ((u64)~0ULL)
>> +
>> extern unsigned long total_forks;
>> extern int nr_threads;
>> DECLARE_PER_CPU(unsigned long, process_counts);
>> @@ -3002,6 +3007,10 @@ extern long sched_getaffinity(pid_t pid, struct cpumask *mask);
>>
>> #ifdef CONFIG_CGROUP_SCHED
>> extern struct task_group root_task_group;
>> +#ifdef CONFIG_CFS_BANDWIDTH
>> +extern int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us);
>> +extern int tg_set_cfs_period(struct task_group *tg, long cfs_period_us);
>> +#endif /* CONFIG_CFS_BANDWIDTH */
>> #endif /* CONFIG_CGROUP_SCHED */
>>
>> extern int task_can_switch_user(struct user_struct *up,
>> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
>> index e628cb1..7471b06 100644
>> --- a/kernel/sched/core.c
>> +++ b/kernel/sched/core.c
>> @@ -7097,6 +7097,7 @@ int in_sched_functions(unsigned long addr)
>> * Every task in system belongs to this group at bootup.
>> */
>> struct task_group root_task_group;
>> +EXPORT_SYMBOL_GPL(root_task_group);
>> LIST_HEAD(task_groups);
>> #endif
>>
>> @@ -8059,9 +8060,6 @@ static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota)
>> int i, ret = 0, runtime_enabled, runtime_was_enabled;
>> struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
>>
>> - if (tg == &root_task_group)
>> - return -EINVAL;
>> -
>> /*
>> * Ensure we have at some amount of bandwidth every period. This is
>> * to prevent reaching a state of large arrears when throttled via
>> @@ -8141,6 +8139,7 @@ int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us)
>>
>> return tg_set_cfs_bandwidth(tg, period, quota);
>> }
>> +EXPORT_SYMBOL_GPL(tg_set_cfs_quota);
>>
>> long tg_get_cfs_quota(struct task_group *tg)
>> {
>> @@ -8164,6 +8163,7 @@ int tg_set_cfs_period(struct task_group *tg, long cfs_period_us)
>>
>> return tg_set_cfs_bandwidth(tg, period, quota);
>> }
>> +EXPORT_SYMBOL_GPL(tg_set_cfs_period);
>>
>> long tg_get_cfs_period(struct task_group *tg)
>> {
>> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
>> index 9a2a45c..20493e4 100644
>> --- a/kernel/sched/sched.h
>> +++ b/kernel/sched/sched.h
>> @@ -72,11 +72,6 @@ extern void update_cpu_load_active(struct rq *this_rq);
>> * These are the 'tuning knobs' of the scheduler:
>> */
>>
>> -/*
>> - * single value that denotes runtime == period, ie unlimited time.
>> - */
>> -#define RUNTIME_INF ((u64)~0ULL)
>> -
>> static inline int fair_policy(int policy)
>> {
>> return policy == SCHED_NORMAL || policy == SCHED_BATCH;
>>
--
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