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This change has been made by an automated script, maintained by the
Ubuntu Kernel Team.
** Changed in: linux (Ubuntu)
Status: New => Incomplete
** Changed in: linux (Ubuntu Xenial)
Status: New => Incomplete
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https://bugs.launchpad.net/bugs/1579278
Title:
Consider changing default CPU frequency scaling governor back to
"performance"
Status in linux package in Ubuntu:
Incomplete
Status in linux source package in Xenial:
Incomplete
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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