On Fri, 2014-04-11 at 05:52 +0200, Mike Galbraith wrote:
> On Thu, 2014-04-10 at 23:25 -0400, Steven Rostedt wrote:
> > On Fri, 11 Apr 2014 04:50:26 +0200
> > Mike Galbraith <umgwanakikbuti@xxxxxxxxx> wrote:
> >
> > > Oh, there was another useful bit.
> > >
> > > 3.12.17-rt25 403991 384216 377786
> > > 405466 394011 392850
> > >
> > > 3.12.17-nopreempt 109049 186133 118766 !?!.. ew, TTWU_QUEUE
> > > 350385 318786 367336 !TTWU_QUEUE
> > > 326009 356939 378215 !TTWU_QUEUE
> > >
> > > IPI == low-pass filter.
> >
> > I'm sorry, but I don't have the foggiest clue to what the above means.
>
> It means..
>
> # Overhead Symbol
> # ........ .......................................................................................................................................................................................
> #
> 17.33% [k] native_write_msr_safe
> |
> |--88.45%-- __x2apic_send_IPI_mask
> | |
> | |--97.89%-- try_to_wake_up
> | | |
> | | |--99.91%-- wake_futex
> | | | |
> | | | |--99.77%-- futex_wake_op
> | | | | do_futex
> | | | | sys_futex
> | | | | system_call_fastpath
>
> ..wakeup frequency is restricted by the IPI.
Turn TTWU_QUEUE off, bottleneck goes away.
# Overhead Symbol
# ........ .......................................................................................................................................................................................
#
6.12% [.] _ZN13ObjectMonitor20TrySpin_VaryDurationEP6Thread
|
|--61.27%-- _ZN13ObjectMonitor5enterEP6Thread
| |
| |--99.96%-- _ZN13SharedRuntime26complete_monitor_locking_CEP7oopDescP9BasicLockP10JavaThread
| | 0x7f93149b2748
| | |
| | |--99.76%-- 0xf1a02b30
| | | 0xbaba00000000fc24
| | --0.24%-- [...]
| --0.04%-- [...]
|
|--38.40%-- _ZN13ObjectMonitor6EnterIEP6Thread
| _ZN13ObjectMonitor5enterEP6Thread
| |
| |--99.98%-- _ZN13SharedRuntime26complete_monitor_locking_CEP7oopDescP9BasicLockP10JavaThread
| | 0x7f93149b2748
| | |
| | |--99.89%-- 0xf1a02b30
| | | 0xbaba00000000fc24
| | --0.11%-- [...]
| --0.02%-- [...]
--0.32%-- [...]
3.59% [k] intel_idle
|
--- cpuidle_enter_state
cpuidle_idle_call
arch_cpu_idle
cpu_startup_entry
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