Using kernel 4.8-rc5 I did some energy tests, using a SpecPower simulator that
I made one time. I reused intel_pstate powersave data from a previous test.
Reference:
http://marc.info/?l=linux-kernel&m=147326197513427&w=2
Big numbers are Joules (package Joules from turbostat)
Smaller numbers are watts, 1500 Seconds test run time.
X ~= 18.2% on a real SpecPower.
Load: idle 0.5X X 2X 3X 4X 5X 100%
powersave 5708 11037 16075 29147 45913 61165 76650 81695
3.81 7.36 10.72 19.43 30.61 40.78 51.10 54.46
performance 5749 14536 22841 38475 51757 64425 77000 81733
3.83 9.69 15.23 25.65 34.50 42.95 51.33 54.49
0.7% 31.7% 42.1% 32.0% 12.7% 5.3% 0.5% 0.0%
Note: A real SpecPower test-bed tends to get less dramatic results than
my simulator.
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https://bugs.launchpad.net/bugs/1579278
Title:
Keep powersave CPU frequency scaling governor for CPUs that support
intel_pstate
Status in linux package in Ubuntu:
Invalid
Status in systemd package in Ubuntu:
Fix Released
Status in sysvinit package in Ubuntu:
Invalid
Status in linux source package in Xenial:
Invalid
Status in systemd source package in Xenial:
Invalid
Status in sysvinit source package in Xenial:
Triaged
Bug description:
Hi,
With the new Ubuntu archive servers, we saw constantly high load and
after some tinkering, we found that it was mostly CPUs being woken up
to see if they should enter idle states. Changing the CPU frequency
scaling governor to "performance" saw a considerable drop.
Perf report using the following commands:
| perf record -g -a sleep 10
| perf report
| Samples: 287K of event 'cycles:pp', Event count (approx.): 124776998906
| Children Self Command Shared Object Symbol
| + 55.24% 0.20% swapper [kernel.kallsyms] [k]
cpu_startup_entry
| + 53.51% 0.00% swapper [kernel.kallsyms] [k]
start_secondary
| + 53.02% 0.08% swapper [kernel.kallsyms] [k]
call_cpuidle
| + 52.94% 0.02% swapper [kernel.kallsyms] [k]
cpuidle_enter
| + 31.81% 0.67% swapper [kernel.kallsyms] [k]
cpuidle_enter_state
| + 29.59% 0.12% swapper [kernel.kallsyms] [k]
acpi_idle_enter
| + 29.45% 0.05% swapper [kernel.kallsyms] [k]
acpi_idle_do_entry
| + 29.43% 29.43% swapper [kernel.kallsyms] [k]
acpi_processor_ffh_cstate_enter
| + 20.51% 0.04% swapper [kernel.kallsyms] [k]
ret_from_intr
| + 20.47% 0.12% swapper [kernel.kallsyms] [k] do_IRQ
| + 19.30% 0.07% swapper [kernel.kallsyms] [k]
irq_exit
| + 19.18% 0.07% apache2 [kernel.kallsyms] [k]
entry_SYSCALL_64_fastpath
| + 18.80% 0.17% swapper [kernel.kallsyms] [k]
__do_softirq
| + 16.45% 0.11% swapper [kernel.kallsyms] [k]
net_rx_action
| + 16.25% 0.43% swapper [kernel.kallsyms] [k] be_poll
| + 14.74% 0.21% swapper [kernel.kallsyms] [k]
be_process_rx
| + 13.61% 0.07% swapper [kernel.kallsyms] [k]
napi_gro_frags
| + 12.58% 0.04% swapper [kernel.kallsyms] [k]
netif_receive_skb_internal
| + 12.48% 0.03% swapper [kernel.kallsyms] [k]
__netif_receive_skb
| + 12.42% 0.24% swapper [kernel.kallsyms] [k]
__netif_receive_skb_core
| + 12.41% 0.00% apache2 [unknown] [k]
0x00007f27983b5028
| + 12.41% 0.00% apache2 [unknown] [k]
0x00007f2798369028
| + 11.49% 0.16% swapper [kernel.kallsyms] [k] ip_rcv
| + 11.29% 0.09% swapper [kernel.kallsyms] [k]
ip_rcv_finish
| + 10.77% 0.05% swapper [kernel.kallsyms] [k]
ip_local_deliver
| + 10.70% 0.06% swapper [kernel.kallsyms] [k]
ip_local_deliver_finish
| + 10.55% 0.22% swapper [kernel.kallsyms] [k]
tcp_v4_rcv
| + 10.10% 0.00% apache2 [unknown] [k]
0000000000000000
| + 10.01% 0.04% swapper [kernel.kallsyms] [k]
tcp_v4_do_rcv
Expanding in a few of those, you'll see:
| - 55.24% 0.20% swapper [kernel.kallsyms] [k]
cpu_startup_entry
| - 55.04% cpu_startup_entry
| - 52.98% call_cpuidle
| + 52.93% cpuidle_enter
| + 0.00% ret_from_intr
| 0.00% cpuidle_enter_state
| 0.00% irq_entries_start
| + 1.14% cpuidle_select
| + 0.47% schedule_preempt_disabled
| 0.10% rcu_idle_enter
| 0.09% rcu_idle_exit
| + 0.05% ret_from_intr
| + 0.05% tick_nohz_idle_enter
| + 0.04% arch_cpu_idle_enter
| 0.02% cpuidle_enter
| 0.02% tick_check_broadcast_expired
| + 0.01% cpuidle_reflect
| 0.01% menu_reflect
| 0.01% atomic_notifier_call_chain
| 0.01% local_touch_nmi
| 0.01% cpuidle_not_available
| 0.01% menu_select
| 0.01% cpuidle_get_cpu_driver
| + 0.01% tick_nohz_idle_exit
| + 0.01% sched_ttwu_pending
| 0.00% set_cpu_sd_state_idle
| 0.00% native_irq_return_iret
| 0.00% schedule
| + 0.00% arch_cpu_idle_exit
| 0.00% __tick_nohz_idle_enter
| 0.00% irq_entries_start
| 0.00% sched_clock_idle_wakeup_event
| 0.00% reschedule_interrupt
| + 0.00% apic_timer_interrupt
| + 0.20% start_secondary
| + 0.00% x86_64_start_kernel
| + 53.51% 0.00% swapper [kernel.kallsyms] [k]
start_secondary
| + 53.02% 0.08% swapper [kernel.kallsyms] [k]
call_cpuidle
| - 52.94% 0.02% swapper [kernel.kallsyms] [k]
cpuidle_enter
| - 52.92% cpuidle_enter
| + 31.81% cpuidle_enter_state
| + 20.01% ret_from_intr
| + 0.51% apic_timer_interrupt
| 0.28% native_irq_return_iret
| + 0.09% reschedule_interrupt
| 0.05% irq_entries_start
| 0.05% do_IRQ
| 0.05% common_interrupt
| 0.02% sched_idle_set_state
| 0.01% acpi_idle_enter
| 0.01% ktime_get
| 0.01% restore_regs_and_iret
| 0.01% restore_c_regs_and_iret
| + 0.01% call_function_single_interrupt
| 0.00% native_iret
| + 0.00% call_function_interrupt
| 0.00% smp_apic_timer_interrupt
| 0.00% smp_reschedule_interrupt
| 0.00% smp_call_function_single_interrupt
| + 0.02% start_secondary
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