Date: Sun, 27 Mar 2016 14:09:14 -0700
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>,
        Josh Triplett <josh@joshtriplett.org>, Ross Green <rgkernel@gmail.com>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        John Stultz <john.stultz@linaro.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        lkml <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@kernel.org>,
        Lai Jiangshan <jiangshanlai@gmail.com>, dipankar@in.ibm.com,
        Andrew Morton <akpm@linux-foundation.org>,
        rostedt <rostedt@goodmis.org>, David Howells <dhowells@redhat.com>,
        Eric Dumazet <edumazet@google.com>,
        Darren Hart <dvhart@linux.intel.com>,
        =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>,
        Oleg Nesterov <oleg@redhat.com>, pranith kumar <bobby.prani@gmail.com>,
        "Chatre, Reinette" <reinette.chatre@intel.com>
Subject: Re: rcu_preempt self-detected stall on CPU from 4.5-rc3, since 3.17
Message-ID: <20160327210914.GD4287@linux.vnet.ibm.com>
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On Sun, Mar 27, 2016 at 10:54:39PM +0200, Peter Zijlstra wrote:
> On Mon, Mar 21, 2016 at 09:22:30AM -0700, Jacob Pan wrote:
> > > > We're seeing a similar stall (~60 seconds) on an x86 development
> > > > system here.  Any luck tracking down the cause of this?  If not, any
> > > > suggestions for traces that might be helpful?
> 
> > +Reinette, she has the system that can reproduce the issue. I
> > believe she is having some other problems with it at the moment. But
> > the .config should be available. Version is v4.5.
> 
> Does that system have MONITOR/MWAIT errata?

On the off-chance that this question was also directed at me, here is
what I am running on.  I am running in a qemu/KVM virtual machine, in
case that matters.

							Thanx, Paul

processor       : 63
vendor_id       : GenuineIntel
cpu family      : 6
model           : 47
model name      : Intel(R) Xeon(R) CPU E7- 4820  @ 2.00GHz
stepping        : 2
microcode       : 0x37
cpu MHz         : 1064.000
cache size      : 18432 KB
physical id     : 3
siblings        : 16
core id         : 25
cpu cores       : 8
apicid          : 243
initial apicid  : 243
fpu             : yes
fpu_exception   : yes
cpuid level     : 11
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic popcnt aes lahf_lm ida arat epb dtherm tpr_shadow vnmi flexpriority ept vpid
bogomips        : 3990.01
clflush size    : 64
cache_alignment : 64
address sizes   : 44 bits physical, 48 bits virtual
power management: