From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org, mingo@kernel.org,
jiangshanlai@gmail.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
josh@joshtriplett.org, tglx@linutronix.de, rostedt@goodmis.org,
dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com,
oleg@redhat.com, bobby.prani@gmail.com
Subject: Re: [PATCH tip/core/rcu 04/13] rcu: Make RCU_FANOUT_LEAF help text more explicit about skew_tick
Date: Wed, 19 Apr 2017 09:13:53 -0700 [thread overview]
Message-ID: <20170419161353.GS3956@linux.vnet.ibm.com> (raw)
In-Reply-To: <20170419154040.knkdg2j6awrp74ua@hirez.programming.kicks-ass.net>
On Wed, Apr 19, 2017 at 05:40:40PM +0200, Peter Zijlstra wrote:
> On Wed, Apr 19, 2017 at 08:08:09AM -0700, Paul E. McKenney wrote:
> > And even that would not be completely sufficient. After all, the state
> > in the leaf rcu_node structure will be out of date during grace-period
> > initialization and cleanup. So to -completely- synchronize state for
> > the incoming CPU, I would have to acquire the root rcu_node structure's
> > lock and look at the live state. Needless to say, the performance and
> > scalability implications of acquiring a global lock on each and every
> > idle exit event is not going to be at all pretty.
>
> Arguably you could use a seqlock to read the global state. Will still
> ponder things a bit more, esp. those bugs you pointed me at from just
> reading gpnum.
Looking forward to hearing what you come up with!
Thanx, Paul
next prev parent reply other threads:[~2017-04-19 16:14 UTC|newest]
Thread overview: 119+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-12 16:54 [PATCH tip/core/rcu 0/13] Miscellaneous fixes for 4.12 Paul E. McKenney
2017-04-12 16:55 ` [PATCH tip/core/rcu 01/13] mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU Paul E. McKenney
2017-04-12 16:55 ` Paul E. McKenney
2017-04-13 9:12 ` Peter Zijlstra
2017-04-13 9:12 ` Peter Zijlstra
2017-04-13 11:06 ` Vlastimil Babka
2017-04-13 11:06 ` Vlastimil Babka
2017-04-13 16:00 ` Paul E. McKenney
2017-04-13 16:00 ` Paul E. McKenney
2017-04-13 16:17 ` Peter Zijlstra
2017-04-13 16:17 ` Peter Zijlstra
2017-04-13 17:24 ` Paul E. McKenney
2017-04-13 17:24 ` Paul E. McKenney
2017-04-13 21:30 ` Eric Dumazet
2017-04-13 21:30 ` Eric Dumazet
2017-04-14 8:45 ` Peter Zijlstra
2017-04-14 8:45 ` Peter Zijlstra
2017-04-14 13:39 ` Paul E. McKenney
2017-04-14 13:39 ` Paul E. McKenney
2017-04-12 16:55 ` [PATCH tip/core/rcu 02/13] lockdep: Use "WARNING" tag on lockdep splats Paul E. McKenney
2017-04-13 9:14 ` Peter Zijlstra
2017-04-13 16:01 ` Paul E. McKenney
2017-04-12 16:55 ` [PATCH tip/core/rcu 03/13] types: Update obsolete callback_head comment Paul E. McKenney
2017-04-12 16:55 ` [PATCH tip/core/rcu 04/13] rcu: Make RCU_FANOUT_LEAF help text more explicit about skew_tick Paul E. McKenney
2017-04-13 9:15 ` Peter Zijlstra
2017-04-13 16:03 ` Paul E. McKenney
2017-04-13 16:19 ` Peter Zijlstra
2017-04-13 16:55 ` Paul E. McKenney
2017-04-13 17:04 ` Peter Zijlstra
2017-04-13 17:31 ` Paul E. McKenney
2017-04-13 17:46 ` Peter Zijlstra
2017-04-13 18:19 ` Paul E. McKenney
2017-04-13 18:23 ` Peter Zijlstra
2017-04-13 18:42 ` Paul E. McKenney
2017-04-19 13:22 ` Peter Zijlstra
2017-04-19 13:48 ` Peter Zijlstra
2017-04-19 15:08 ` Paul E. McKenney
2017-04-19 15:40 ` Peter Zijlstra
2017-04-19 16:13 ` Paul E. McKenney [this message]
2017-04-19 14:50 ` Paul E. McKenney
2017-04-13 18:29 ` Peter Zijlstra
2017-04-13 19:42 ` Paul E. McKenney
2017-04-12 16:55 ` [PATCH tip/core/rcu 05/13] rcu: Remove obsolete comment from rcu_future_gp_cleanup() header Paul E. McKenney
2017-04-12 16:55 ` [PATCH tip/core/rcu 06/13] hlist_add_tail_rcu disable sparse warning Paul E. McKenney
2017-04-12 16:55 ` [PATCH tip/core/rcu 07/13] rcu: Add smp_mb__after_atomic() to sync_exp_work_done() Paul E. McKenney
2017-04-13 9:18 ` Peter Zijlstra
2017-04-13 9:33 ` Peter Zijlstra
2017-04-13 16:10 ` Paul E. McKenney
2017-04-13 16:24 ` Peter Zijlstra
2017-04-13 16:57 ` Paul E. McKenney
2017-04-13 17:10 ` Peter Zijlstra
2017-04-13 17:39 ` Paul E. McKenney
2017-04-13 17:51 ` Peter Zijlstra
2017-04-13 17:59 ` Peter Zijlstra
2017-04-19 23:24 ` Paul E. McKenney
2017-04-19 23:23 ` Paul E. McKenney
2017-04-20 11:17 ` Peter Zijlstra
2017-04-20 15:03 ` Paul E. McKenney
2017-04-20 15:08 ` Peter Zijlstra
2017-06-09 22:56 ` Paul E. McKenney
2017-06-12 14:51 ` Dmitry Vyukov
2017-06-12 21:54 ` Paul E. McKenney
2017-04-12 16:55 ` [PATCH tip/core/rcu 08/13] rcu: Improve comments for hotplug/suspend/hibernate functions Paul E. McKenney
2017-04-12 16:55 ` [PATCH tip/core/rcu 09/13] mm: Use static initialization for "srcu" Paul E. McKenney
2017-04-12 16:55 ` Paul E. McKenney
2017-04-12 16:55 ` [PATCH tip/core/rcu 10/13] torture: Use correct path for Kconfig fragment for duplicates Paul E. McKenney
2017-04-12 16:55 ` [PATCH tip/core/rcu 11/13] rcu: Use bool value directly Paul E. McKenney
2017-04-12 16:55 ` [PATCH tip/core/rcu 12/13] rcu: Use true/false in assignment to bool Paul E. McKenney
2017-04-12 16:55 ` [PATCH tip/core/rcu 13/13] rcu: Fix typo in PER_RCU_NODE_PERIOD header comment Paul E. McKenney
2017-04-17 23:27 ` [PATCH v2 tip/core/rcu 0/13] Miscellaneous fixes for 4.12 Paul E. McKenney
2017-04-17 23:28 ` [PATCH v2 tip/core/rcu 01/11] mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU Paul E. McKenney
2017-04-17 23:28 ` Paul E. McKenney
2017-04-18 0:14 ` David Rientjes
2017-04-18 0:14 ` David Rientjes
2017-04-17 23:28 ` [PATCH v2 tip/core/rcu 02/11] lockdep: Use "WARNING" tag on lockdep splats Paul E. McKenney
2017-04-19 15:00 ` Josh Triplett
2017-04-19 16:26 ` Paul E. McKenney
2017-04-17 23:28 ` [PATCH v2 tip/core/rcu 03/11] types: Update obsolete callback_head comment Paul E. McKenney
2017-04-17 23:28 ` [PATCH v2 tip/core/rcu 04/11] rcu: Make RCU_FANOUT_LEAF help text more explicit about skew_tick Paul E. McKenney
2017-04-18 0:18 ` Josh Triplett
2017-04-18 18:42 ` Paul E. McKenney
2017-04-17 23:28 ` [PATCH v2 tip/core/rcu 05/11] rcu: Remove obsolete comment from rcu_future_gp_cleanup() header Paul E. McKenney
2017-04-17 23:28 ` [PATCH v2 tip/core/rcu 06/11] hlist_add_tail_rcu disable sparse warning Paul E. McKenney
2017-04-17 23:28 ` [PATCH v2 tip/core/rcu 07/11] rcu: Improve comments for hotplug/suspend/hibernate functions Paul E. McKenney
2017-04-17 23:28 ` [PATCH v2 tip/core/rcu 08/11] torture: Use correct path for Kconfig fragment for duplicates Paul E. McKenney
2017-04-17 23:28 ` [PATCH v2 tip/core/rcu 09/11] rcu: Use bool value directly Paul E. McKenney
2017-04-17 23:28 ` [PATCH v2 tip/core/rcu 10/11] rcu: Use true/false in assignment to bool Paul E. McKenney
2017-04-17 23:28 ` [PATCH v2 tip/core/rcu 11/11] rcu: Fix typo in PER_RCU_NODE_PERIOD header comment Paul E. McKenney
2017-04-19 11:28 ` [PATCH v2 tip/core/rcu 0/13] Miscellaneous fixes for 4.12 Peter Zijlstra
2017-04-19 11:35 ` Peter Zijlstra
2017-04-19 11:48 ` Christian Borntraeger
2017-04-19 12:08 ` Peter Zijlstra
2017-04-19 12:51 ` Marc Zyngier
2017-04-19 14:47 ` Paul E. McKenney
2017-04-19 14:52 ` Peter Zijlstra
2017-04-19 15:13 ` Paul E. McKenney
2017-04-19 14:58 ` Josh Triplett
2017-04-19 15:03 ` Peter Zijlstra
2017-04-19 15:17 ` Paul E. McKenney
2017-04-19 13:22 ` Paul E. McKenney
2017-04-19 13:25 ` Christian Borntraeger
2017-04-19 13:02 ` Paul E. McKenney
2017-04-19 13:15 ` Peter Zijlstra
2017-04-19 15:37 ` Paul E. McKenney
2017-04-19 15:43 ` Peter Zijlstra
2017-04-19 16:12 ` Paul E. McKenney
2017-04-19 16:45 ` Paul E. McKenney
2017-04-19 16:46 ` [PATCH v3 tip/core/rcu 01/11] mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU Paul E. McKenney
2017-04-19 16:46 ` Paul E. McKenney
2017-04-19 16:46 ` [PATCH v3 tip/core/rcu 02/11] lockdep: Use "WARNING" tag on lockdep splats Paul E. McKenney
2017-04-19 16:46 ` [PATCH v3 tip/core/rcu 03/11] types: Update obsolete callback_head comment Paul E. McKenney
2017-04-19 16:46 ` [PATCH v3 tip/core/rcu 04/11] rcu: Make RCU_FANOUT_LEAF help text more explicit about skew_tick Paul E. McKenney
2017-04-19 16:46 ` [PATCH v3 tip/core/rcu 05/11] rcu: Remove obsolete comment from rcu_future_gp_cleanup() header Paul E. McKenney
2017-04-19 16:46 ` [PATCH v3 tip/core/rcu 06/11] hlist_add_tail_rcu disable sparse warning Paul E. McKenney
2017-04-19 16:46 ` [PATCH v3 tip/core/rcu 07/11] rcu: Improve comments for hotplug/suspend/hibernate functions Paul E. McKenney
2017-04-19 16:46 ` [PATCH v3 tip/core/rcu 08/11] torture: Use correct path for Kconfig fragment for duplicates Paul E. McKenney
2017-04-19 16:46 ` [PATCH v3 tip/core/rcu 09/11] rcu: Use bool value directly Paul E. McKenney
2017-04-19 16:46 ` [PATCH v3 tip/core/rcu 10/11] rcu: Use true/false in assignment to bool Paul E. McKenney
2017-04-19 16:46 ` [PATCH v3 tip/core/rcu 11/11] rcu: Fix typo in PER_RCU_NODE_PERIOD header comment Paul E. McKenney
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