From: Frederic Weisbecker <fweisbec@gmail.com>
To: Josh Triplett <josh@joshtriplett.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
linux-kernel@vger.kernel.org, mingo@elte.hu,
laijs@cn.fujitsu.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca,
niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org,
rostedt@goodmis.org, Valdis.Kletnieks@vt.edu,
dhowells@redhat.com, eric.dumazet@gmail.com, darren@dvhart.com,
sbw@mit.edu, patches@linaro.org,
Alessio Igor Bogani <abogani@kernel.org>,
Avi Kivity <avi@redhat.com>, Chris Metcalf <cmetcalf@tilera.com>,
Christoph Lameter <cl@linux.com>,
Geoff Levand <geoff@infradead.org>,
Gilad Ben Yossef <gilad@benyossef.com>,
Hakan Akkan <hakanakkan@gmail.com>,
"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@kernel.org>,
Kevin Hilman <khilman@ti.com>,
Max Krasnyansky <maxk@qualcomm.com>,
Stephen Hemminger <shemminger@vyatta.com>,
Sven-Thorsten Dietrich <thebigcorporation@gmail.com>
Subject: Re: [PATCH tip/core/rcu 04/26] rcu: Settle config for userspace extended quiescent state
Date: Mon, 10 Sep 2012 23:35:19 +0200 [thread overview]
Message-ID: <20120910213506.GC21277@somewhere.redhat.com> (raw)
In-Reply-To: <20120905004619.GB12373@jtriplet-mobl1>
On Tue, Sep 04, 2012 at 05:46:19PM -0700, Josh Triplett wrote:
> > It actually does depend on SMP. There has to be at least one CPU taking
> > scheduling-clock interrupts in order to keep time computation accurate,
> > so a de-facto UP system cannot adaptive-dynticks its sole CPU.
>
> Ah. That seems like a removable limitation, albeit a difficult one.
> Nonetheless, it makes sense to avoid providing the option when it won't
> help.
>
> However, once a config symbol for adaptive dynticks exists, perhaps that
> symbol should depend on SMP and RCU_USER_QS should depend on that
> instead, documenting the limitation in the right place and making it
> easier to find and change eventually.
Right! And in fact CONFIG_RCU_USER_QS is a temporary config. Once we'll have
CONFIG_NO_HZ_FULL, we won't need intermediate configs like this.
And CONFIG_NO_HZ_FULL will depend on SMP anyway.
next prev parent reply other threads:[~2012-09-10 21:35 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-30 21:05 [PATCH tip/core/rcu 0/26] idle-related changes Paul E. McKenney
2012-08-30 21:05 ` [PATCH tip/core/rcu 01/26] rcu: New rcu_user_enter() and rcu_user_exit() APIs Paul E. McKenney
2012-08-30 21:05 ` [PATCH tip/core/rcu 02/26] rcu: New rcu_user_enter_irq() and rcu_user_exit_irq() APIs Paul E. McKenney
2012-08-31 19:13 ` Josh Triplett
2012-08-31 19:54 ` Frederic Weisbecker
2012-08-31 21:38 ` Josh Triplett
2012-08-30 21:05 ` [PATCH tip/core/rcu 03/26] rcu: Make RCU_FAST_NO_HZ handle adaptive ticks Paul E. McKenney
2012-08-31 23:40 ` Josh Triplett
2012-08-30 21:05 ` [PATCH tip/core/rcu 04/26] rcu: Settle config for userspace extended quiescent state Paul E. McKenney
2012-08-31 23:44 ` Josh Triplett
2012-09-05 0:34 ` Paul E. McKenney
2012-09-05 0:46 ` Josh Triplett
2012-09-10 21:35 ` Frederic Weisbecker [this message]
2012-08-30 21:05 ` [PATCH tip/core/rcu 05/26] rcu: Allow rcu_user_enter()/exit() to nest Paul E. McKenney
2012-08-31 23:45 ` Josh Triplett
2012-08-30 21:05 ` [PATCH tip/core/rcu 06/26] rcu: Ignore userspace extended quiescent state by default Paul E. McKenney
2012-08-31 23:46 ` Josh Triplett
2012-08-30 21:05 ` [PATCH tip/core/rcu 07/26] rcu: Switch task's syscall hooks on context switch Paul E. McKenney
2012-08-31 23:48 ` Josh Triplett
2012-08-30 21:05 ` [PATCH tip/core/rcu 08/26] x86: Syscall hooks for userspace RCU extended QS Paul E. McKenney
2012-08-31 23:59 ` Josh Triplett
2012-09-10 21:30 ` Frederic Weisbecker
2012-08-30 21:05 ` [PATCH tip/core/rcu 09/26] x86: Exception " Paul E. McKenney
2012-08-31 23:51 ` Josh Triplett
2012-08-30 21:05 ` [PATCH tip/core/rcu 10/26] rcu: Exit RCU extended QS on kernel preemption after irq/exception Paul E. McKenney
2012-08-31 23:51 ` Josh Triplett
2012-09-06 16:52 ` Peter Zijlstra
2012-09-10 20:31 ` Frederic Weisbecker
2012-08-30 21:05 ` [PATCH tip/core/rcu 11/26] rcu: Exit RCU extended QS on user preemption Paul E. McKenney
2012-08-31 23:52 ` Josh Triplett
2012-09-06 17:02 ` Peter Zijlstra
2012-09-06 17:13 ` Peter Zijlstra
2012-09-10 20:26 ` Frederic Weisbecker
2012-09-12 9:33 ` Peter Zijlstra
2012-09-12 12:06 ` Frederic Weisbecker
2012-09-12 12:41 ` Peter Zijlstra
2012-09-12 12:52 ` Peter Zijlstra
2012-09-12 13:54 ` Frederic Weisbecker
2012-09-12 14:09 ` Peter Zijlstra
2012-09-12 13:52 ` Frederic Weisbecker
2012-09-12 15:21 ` Paul E. McKenney
2012-08-30 21:05 ` [PATCH tip/core/rcu 12/26] x86: Use the new schedule_user API on userspace preemption Paul E. McKenney
2012-08-31 23:53 ` Josh Triplett
2012-08-30 21:05 ` [PATCH tip/core/rcu 13/26] x86: Exit RCU extended QS on notify resume Paul E. McKenney
2012-08-31 23:54 ` Josh Triplett
2012-08-30 21:05 ` [PATCH tip/core/rcu 14/26] rcu: Userspace RCU extended QS selftest Paul E. McKenney
2012-08-31 23:54 ` Josh Triplett
2012-08-30 21:05 ` [PATCH tip/core/rcu 15/26] alpha: Fix preemption handling in idle loop Paul E. McKenney
2012-08-31 23:55 ` Josh Triplett
2012-08-30 21:05 ` [PATCH tip/core/rcu 16/26] alpha: Add missing RCU idle APIs on " Paul E. McKenney
2012-09-01 0:00 ` Josh Triplett
2012-08-30 21:05 ` [PATCH tip/core/rcu 17/26] cris: " Paul E. McKenney
2012-09-01 0:01 ` Josh Triplett
2012-08-30 21:05 ` [PATCH tip/core/rcu 18/26] frv: " Paul E. McKenney
2012-09-01 0:01 ` Josh Triplett
2012-08-30 21:05 ` [PATCH tip/core/rcu 19/26] h8300: " Paul E. McKenney
2012-09-01 0:02 ` Josh Triplett
2012-08-30 21:05 ` [PATCH tip/core/rcu 20/26] m32r: " Paul E. McKenney
2012-09-01 0:02 ` Josh Triplett
2012-08-30 21:05 ` [PATCH tip/core/rcu 21/26] m68k: " Paul E. McKenney
2012-09-01 0:02 ` Josh Triplett
2012-08-30 21:05 ` [PATCH tip/core/rcu 22/26] mn10300: " Paul E. McKenney
2012-09-01 0:03 ` Josh Triplett
2012-08-30 21:05 ` [PATCH tip/core/rcu 23/26] parisc: " Paul E. McKenney
2012-09-01 0:03 ` Josh Triplett
2012-08-30 21:05 ` [PATCH tip/core/rcu 24/26] score: " Paul E. McKenney
2012-09-01 0:04 ` Josh Triplett
2012-08-30 21:05 ` [PATCH tip/core/rcu 25/26] xtensa: " Paul E. McKenney
2012-09-01 0:05 ` Josh Triplett
2012-08-30 21:05 ` [PATCH tip/core/rcu 26/26] ia64: " Paul E. McKenney
2012-09-01 0:05 ` Josh Triplett
2012-08-31 19:07 ` [PATCH tip/core/rcu 01/26] rcu: New rcu_user_enter() and rcu_user_exit() APIs Josh Triplett
2012-09-05 1:04 ` Paul E. McKenney
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