From: Mike Galbraith <umgwanakikbuti@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
linux-rt-users <linux-rt-users@vger.kernel.org>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Paul Gortmaker <paul.gortmaker@windriver.com>,
Thomas Gleixner <tglx@linutronix.de>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Clark Williams <williams@redhat.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>
Subject: Re: [RFC PATCH RT] rwsem: The return of multi-reader PI rwsems
Date: Fri, 11 Apr 2014 06:25:27 +0200 [thread overview]
Message-ID: <1397190327.5139.36.camel@marge.simpson.net> (raw)
In-Reply-To: <1397188356.5139.33.camel@marge.simpson.net>
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@gmail.com> 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
next prev parent reply other threads:[~2014-04-11 4:25 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-09 19:19 Steven Rostedt
2014-04-10 14:18 ` Mike Galbraith
2014-04-10 14:28 ` Mike Galbraith
2014-04-10 14:32 ` Steven Rostedt
2014-04-11 2:50 ` Mike Galbraith
2014-04-11 3:25 ` Steven Rostedt
2014-04-11 3:52 ` Mike Galbraith
2014-04-11 4:25 ` Mike Galbraith [this message]
2014-04-10 14:44 ` Clark Williams
2014-04-10 15:01 ` Steven Rostedt
2014-04-10 15:03 ` Sebastian Andrzej Siewior
2014-04-10 15:36 ` Peter Zijlstra
2014-04-10 19:17 ` Steven Rostedt
2014-04-10 20:48 ` Peter Zijlstra
2014-04-10 21:30 ` Paul E. McKenney
2014-04-10 22:02 ` Steven Rostedt
2014-04-10 15:38 ` Steven Rostedt
2014-04-11 21:39 ` Daniel Bristot de Oliveira
2014-04-10 17:42 ` [RFC PATCH RT V2] " Steven Rostedt
2014-04-11 2:35 ` [RFC PATCH RT V3] " Steven Rostedt
2014-04-11 12:47 ` Carsten Emde
2014-04-11 13:25 ` Steven Rostedt
2014-04-17 23:26 ` [RFC PATCH RT V4] " Steven Rostedt
2014-04-18 8:19 ` Ingo Molnar
2014-04-24 17:52 ` Steven Rostedt
2014-04-14 9:55 ` [RFC PATCH RT] " Ingo Molnar
2014-04-14 13:34 ` Steven Rostedt
2014-04-14 14:08 ` Peter Zijlstra
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