From: Dave Hansen <dave.hansen@intel.com>
To: paulmck@linux.vnet.ibm.com
Cc: linux-kernel@vger.kernel.org, mingo@kernel.org,
laijs@cn.fujitsu.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com,
ak@linux.intel.com, cl@gentwo.org, umgwanakikbuti@gmail.com
Subject: Re: [PATCH tip/core/rcu] Reduce overhead of cond_resched() checks for RCU
Date: Tue, 24 Jun 2014 09:18:49 -0700 [thread overview]
Message-ID: <53A9A4E9.5090505@intel.com> (raw)
In-Reply-To: <20140624003934.GR4603@linux.vnet.ibm.com>
On 06/23/2014 05:39 PM, Paul E. McKenney wrote:
> On Mon, Jun 23, 2014 at 05:20:30PM -0700, Dave Hansen wrote:
>> On 06/23/2014 05:15 PM, Paul E. McKenney wrote:
>>> Just out of curiosity, how many CPUs does your system have? 80?
>>> If 160, looks like something bad is happening at 80.
>>
>> 80 cores, 160 threads. >80 processes/threads is where we start using
>> the second thread on the cores. The tasks are also pinned to
>> hyperthread pairs, so they disturb each other, and the scheduler moves
>> them between threads on occasion which causes extra noise.
>
> OK, that could explain the near flattening of throughput near 80
> processes. Is 3.16.0-rc1-pf2 with the two RCU patches?
It's actually with _just_ e552592e03 applied on top of 3.16-rc1.
> If so, is the new sysfs parameter at its default value?
I didn't record that, and I've forgotten. I'll re-run it to verify what
it was.
next prev parent reply other threads:[~2014-06-24 16:19 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-21 2:59 [PATCH tip/core/rcu] Reduce overhead of cond_resched() checks for RCU Paul E. McKenney
2014-06-21 4:29 ` Josh Triplett
2014-06-21 6:06 ` Paul E. McKenney
2014-06-23 13:53 ` Christoph Lameter
2014-06-23 15:26 ` Paul E. McKenney
2014-06-23 6:26 ` Peter Zijlstra
2014-06-23 13:33 ` Paul E. McKenney
2014-06-23 13:51 ` Christoph Lameter
2014-06-23 16:45 ` Paul E. McKenney
2014-06-23 15:49 ` Andi Kleen
2014-06-23 16:43 ` Paul E. McKenney
2014-06-23 17:19 ` Andi Kleen
2014-06-23 17:42 ` Paul E. McKenney
2014-06-23 16:55 ` Dave Hansen
2014-06-23 17:16 ` Paul E. McKenney
2014-06-23 17:34 ` Dave Hansen
2014-06-23 17:17 ` Dave Hansen
2014-06-23 18:09 ` Paul E. McKenney
2014-06-23 23:30 ` Dave Hansen
2014-06-24 0:15 ` Paul E. McKenney
2014-06-24 0:20 ` Dave Hansen
2014-06-24 0:39 ` Paul E. McKenney
2014-06-24 16:18 ` Dave Hansen [this message]
2014-06-24 20:43 ` Dave Hansen
2014-06-24 21:15 ` Paul E. McKenney
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