So it seems we should make the "ondemand" init script a no-op if /sys/devices/system/cpu/cpu0/cpufreq/scaling_driver contains "intel_pstate", since in this case "ondemand" is worse than "performance"?
-- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1579278 Title: Consider changing default CPU frequency scaling governor back to "performance" (Ubuntu Server) Status in linux package in Ubuntu: Invalid Status in sysvinit package in Ubuntu: New Status in linux source package in Xenial: Invalid Status in sysvinit source package in Xenial: New 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 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1579278/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
