Messages in this thread | | | Date | Fri, 24 Jun 2011 14:04:41 -0500 | From | Shawn Bohrer <> | Subject | High IRQ usage on CPU 0 |
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Running 3.0.0-rc4+ I noticed I'm seeing the following on an idle Dell r610 system:
Cpu0 : 0.0%us, 0.0%sy, 0.0%ni, 64.3%id, 0.0%wa, 35.7%hi, 0.0%si, 0.0%st Cpu1 : 0.0%us, 0.0%sy, 0.0%ni, 99.7%id, 0.0%wa, 0.3%hi, 0.0%si, 0.0%st Cpu2 : 0.0%us, 0.0%sy, 0.0%ni, 99.7%id, 0.0%wa, 0.3%hi, 0.0%si, 0.0%st Cpu3 : 0.0%us, 0.0%sy, 0.0%ni, 99.3%id, 0.0%wa, 0.3%hi, 0.3%si, 0.0%st Cpu4 : 0.0%us, 0.0%sy, 0.0%ni, 99.7%id, 0.0%wa, 0.3%hi, 0.0%si, 0.0%st Cpu5 : 0.0%us, 0.0%sy, 0.0%ni, 99.3%id, 0.0%wa, 0.3%hi, 0.3%si, 0.0%st Cpu6 : 0.0%us, 0.0%sy, 0.0%ni, 99.7%id, 0.0%wa, 0.3%hi, 0.0%si, 0.0%st Cpu7 : 0.0%us, 0.0%sy, 0.0%ni,100.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Cpu8 : 0.0%us, 0.0%sy, 0.0%ni, 99.7%id, 0.0%wa, 0.3%hi, 0.0%si, 0.0%st Cpu9 : 0.0%us, 0.0%sy, 0.0%ni, 99.7%id, 0.0%wa, 0.3%hi, 0.0%si, 0.0%st Cpu10 : 0.0%us, 0.0%sy, 0.0%ni, 99.7%id, 0.0%wa, 0.3%hi, 0.0%si, 0.0%st Cpu11 : 0.0%us, 0.0%sy, 0.0%ni,100.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Cpu12 : 0.0%us, 0.0%sy, 0.0%ni, 99.7%id, 0.0%wa, 0.3%hi, 0.0%si, 0.0%st Cpu13 : 0.0%us, 0.0%sy, 0.0%ni, 99.3%id, 0.0%wa, 0.3%hi, 0.3%si, 0.0%st Cpu14 : 0.0%us, 0.0%sy, 0.0%ni, 99.7%id, 0.0%wa, 0.0%hi, 0.3%si, 0.0%st Cpu15 : 0.0%us, 0.0%sy, 0.0%ni, 99.7%id, 0.0%wa, 0.3%hi, 0.0%si, 0.0%st
Watching /proc/interrupts it looks like most of the interrupts on CPU0 are on IRQ 0 from "IO-APIC-edge timer".
perf top -C 0 shows:
--------------------------------------------------------------------- PerfTop: 1024 irqs/sec kernel:100.0% exact: 0.0% [1000Hz cycles], (all, CPU: 0) ---------------------------------------------------------------------
samples pcnt function DSO _______ _____ ___________________________________ _______
11648.00 83.6% default_send_IPI_mask_sequence_phys vmlinux 1548.00 11.1% _raw_spin_lock_irqsave vmlinux 530.00 3.8% intel_idle vmlinux 36.00 0.3% hpet_legacy_next_event vmlinux 28.00 0.2% tick_handle_oneshot_broadcast vmlinux 20.00 0.1% find_next_bit vmlinux 16.00 0.1% find_busiest_group vmlinux 15.00 0.1% _raw_spin_unlock_irqrestore vmlinux 13.00 0.1% cpuidle_idle_call vmlinux 10.00 0.1% _raw_spin_lock vmlinux 9.00 0.1% tick_broadcast_oneshot_control vmlinux 8.00 0.1% notifier_call_chain vmlinux 7.00 0.1% leave_mm vmlinux
For some reason 'perf record -C 0 -g sleep 5' doesn't record anything, but here is the top functions from a 'perf record -a -g sleep 5':
# Events: 77K cycles # # Overhead Command Shared Object Symbol # ........ ............... .................. ................................... # 80.22% swapper [kernel.kallsyms] [k] _raw_spin_lock_irqsave | --- _raw_spin_lock_irqsave | |--89.92%-- clockevents_notify | intel_idle | cpuidle_idle_call | cpu_idle | | | |--98.67%-- start_secondary | | | --1.33%-- rest_init | start_kernel | x86_64_start_reservations | x86_64_start_kernel | |--10.03%-- tick_broadcast_oneshot_control | tick_notify | notifier_call_chain | raw_notifier_call_chain | clockevents_notify | intel_idle | cpuidle_idle_call | cpu_idle | | | |--99.97%-- start_secondary | --0.03%-- [...] --0.05%-- [...]
9.32% swapper [kernel.kallsyms] [k] default_send_IPI_mask_sequence_phys | --- default_send_IPI_mask_sequence_phys physflat_send_IPI_mask lapic_timer_broadcast tick_do_broadcast tick_handle_oneshot_broadcast timer_interrupt handle_irq_event_percpu handle_irq_event handle_edge_irq handle_irq do_IRQ common_interrupt | |--99.91%-- cpuidle_idle_call | cpu_idle | rest_init | start_kernel | x86_64_start_reservations | x86_64_start_kernel --0.09%-- [...]
5.83% swapper [kernel.kallsyms] [k] intel_idle | --- intel_idle | |--99.67%-- cpuidle_idle_call | cpu_idle | | | |--94.19%-- start_secondary | | | --5.81%-- rest_init | start_kernel | x86_64_start_reservations | x86_64_start_kernel --0.33%-- [...]
I'm not sure what other information would be useful here. Please let me know if you need anything else.
Thanks, Shawn
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