From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Alessio Igor Bogani <abogani@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Avi Kivity <avi@redhat.com>, Chris Metcalf <cmetcalf@tilera.com>,
Christoph Lameter <cl@linux.com>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
Geoff Levand <geoff@infradead.org>,
Gilad Ben Yossef <gilad@benyossef.com>,
Hakan Akkan <hakanakkan@gmail.com>, Kevin Hilman <khilman@ti.com>,
Max Krasnyansky <maxk@qualcomm.com>,
Peter Zijlstra <peterz@infradead.org>,
Stephen Hemminger <shemminger@vyatta.com>,
Steven Rostedt <rostedt@goodmis.org>,
Sven-Thorsten Dietrich <thebigcorporation@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 0/2] rcu: Extended quiescent state for adaptive nohz
Date: Sun, 10 Jun 2012 10:54:56 -0700 [thread overview]
Message-ID: <20120610175456.GC2425@linux.vnet.ibm.com> (raw)
In-Reply-To: <20120609225852.GC31957@somewhere.redhat.com>
On Sun, Jun 10, 2012 at 12:58:56AM +0200, Frederic Weisbecker wrote:
> On Thu, Jun 07, 2012 at 03:45:08PM -0700, Paul E. McKenney wrote:
> > > I can see you've implemented a version for TinyRCU. Nohz cpusets only work on
> > > SMP right now because there must be at least one CPU running with the tick
> > > to maintain the timekeeping. I'm pretty confident that one day we'll remove
> > > the jiffies and we'll be able to do the whole timekeeping by using the TSC
> > > or so. There is quite a way before we reach that though.
> >
> > In the meantime, would it make sense to slow the tick rate by a factor
> > of 10 or so on that one CPU when nothing else is going on? Or does
> > timekeeping absolutely require running the tick at full speed?
>
> I'm not sure of the possible consequences of that.
OK, so I will remove the TINY_RCU patches for the moment. If reducing
tick speed on the sole remaining idle CPU ever becomes feasible and
useful, they are easy to add back in.
Thanx, Paul
next prev parent reply other threads:[~2012-06-10 17:57 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-04 12:08 [PATCH 0/2] rcu: Extended quiescent state for adaptive nohz fweisbec
2012-06-04 12:08 ` [PATCH 1/2] rcu: New rcu_user_enter() and rcu_user_exit() APIs fweisbec
2012-06-04 12:08 ` [PATCH 2/2] rcu: New rcu_user_enter_irq() and rcu_user_exit_irq() APIs fweisbec
2012-06-04 18:13 ` [PATCH 0/2] rcu: Extended quiescent state for adaptive nohz Paul E. McKenney
2012-06-04 19:06 ` Frederic Weisbecker
2012-06-04 21:07 ` Paul E. McKenney
2012-06-05 10:31 ` Frederic Weisbecker
2012-06-05 23:46 ` Paul E. McKenney
2012-06-07 14:21 ` Frederic Weisbecker
2012-06-07 22:45 ` Paul E. McKenney
2012-06-09 22:58 ` Frederic Weisbecker
2012-06-10 17:54 ` Paul E. McKenney [this message]
2012-06-09 22:55 ` [PATCH] rcu: Allow calls to rcu_exit_user_irq from nesting irqs Frederic Weisbecker
2012-06-10 18:06 ` Paul E. McKenney
2012-06-10 20:29 ` Frederic Weisbecker
2012-06-10 21:47 ` [PATCH v2] " Frederic Weisbecker
2012-06-11 21:55 ` Paul E. McKenney
2012-06-11 22:06 ` Frederic Weisbecker
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