Date: Fri, 11 Jul 2014 22:15:07 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Christoph Lameter <cl@gentwo.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        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, niv@us.ibm.com,
        tglx@linutronix.de, rostedt@goodmis.org, dhowells@redhat.com,
        edumazet@google.com, dvhart@linux.intel.com, oleg@redhat.com,
        sbw@mit.edu
Subject: Re: [PATCH tip/core/rcu 11/17] rcu: Bind grace-period kthreads to
 non-NO_HZ_FULL CPUs
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On Fri, Jul 11, 2014 at 02:05:08PM -0500, Christoph Lameter wrote:
> The use case is pretty straightforward because we are trying to keep as
> much OS noise as possible off most processors. Processor 0 is the
> sacrificial lamb that will be used for all OS processing and hopefully all
> high latency operations will occur there. Processors 1-X have a tick but
> we still try to keep latencies sane. And then there is X-Y where tick is
> off.

So the problem is -- and this isn't too hard to create -- when we
saturate/overload cpu0 with just the housekeeping. At that point it
would be good if we could scale and use multiple housekeepers.
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