> Ok, so it looks profilable.
>
> The result above is not surprising: most CPUs sit in idle and don't do
> anything,
> while the loop goes on, right?
>
> The interesting thing to profile would be the parallel bring-down, with the
> simplest global lock solution you mentioned. In that case most CPUs should be
> doing 'something' all the time - maybe spinning on the lock, maybe something
> else,
> right?
Again, mostly looks idle.
Events: 5M cycles
31.69% swapper [kernel.kallsyms] [k]
update_cfs_rq_blocked_load
14.22% swapper [kernel.kallsyms] [k] load_balance
12.95% swapper [kernel.kallsyms] [k] ktime_get
4.64% swapper [kernel.kallsyms] [k] idle_cpu
3.46% swapper [kernel.kallsyms] [k] uv_read_rtc
2.26% swapper [kernel.kallsyms] [k]
ktime_get_update_offsets
2.25% swapper [kernel.kallsyms] [k] rcu_check_callbacks
1.72% swapper [kernel.kallsyms] [k] _raw_spin_lock_irqsave
1.57% swapper [kernel.kallsyms] [k] native_write_msr_safe
1.53% swapper [kernel.kallsyms] [k] native_safe_halt
1.52% swapper [kernel.kallsyms] [k] apic_timer_interrupt
1.52% swapper [kernel.kallsyms] [k]
update_blocked_averages
1.51% swapper [kernel.kallsyms] [k] __lock_text_start
1.48% swapper [kernel.kallsyms] [k] rcu_process_gp_end
1.40% swapper [kernel.kallsyms] [k] rcu_process_callbacks
1.19% reboot [kernel.kallsyms] [k] kmem_cache_alloc_node
0.63% swapper [kernel.kallsyms] [k]
check_for_new_grace_period
0.58% swapper [kernel.kallsyms] [k] rebalance_domains
0.55% swapper [kernel.kallsyms] [k] cpumask_next_and
0.54% swapper [kernel.kallsyms] [k] __tick_nohz_idle_enter
0.53% swapper [kernel.kallsyms] [k]
perf_adjust_freq_unthr_context
0.49% swapper [kernel.kallsyms] [k] _raw_spin_lock
Robin
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