From: Josh Triplett <josh@joshtriplett.org>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org, mingo@kernel.org,
jiangshanlai@gmail.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
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, bobby.prani@gmail.com
Subject: Re: [PATCH tip/core/rcu 08/20] rcu: Add long-term CPU kicking
Date: Sun, 15 Jan 2017 23:58:07 -0800 [thread overview]
Message-ID: <20170116075806.toocj5tswpjghd4l@x> (raw)
In-Reply-To: <1484385201-22227-8-git-send-email-paulmck@linux.vnet.ibm.com>
On Sat, Jan 14, 2017 at 01:13:09AM -0800, Paul E. McKenney wrote:
> Commit d2db185bfee8 ("rcu: Remove short-term CPU kicking") removed
> frequent calls to resched_cpu(), which means that the only time
> resched_cpu() is invoked is after an RCU CPU stall warning. Although
> this is good from an avoid-IPIs perspective, we should try to break
> things loose -before- splatting. This commit therefore starts invoking
> resched_cpu() for each holdout at each force-quiescent-state interval
> that is more than halfway through the stall-warning interval.
>
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Could you please reverse the order of patches 7 and 8, so that
unnecessary splats don't occur between the two?
For the patch itself:
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
> kernel/rcu/tree.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index 3c0d6c129718..5a4aaad75e76 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -1220,6 +1220,13 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp,
> rdp->rsp->jiffies_resched += 5; /* Re-enable beating. */
> }
>
> + /*
> + * If more than halfway to RCU CPU stall-warning time, do
> + * a resched_cpu() to try to loosen things up a bit.
> + */
> + if (jiffies - rdp->rsp->gp_start > rcu_jiffies_till_stall_check() / 2)
> + resched_cpu(rdp->cpu);
> +
> return 0;
> }
>
> --
> 2.5.2
>
next prev parent reply other threads:[~2017-01-16 7:58 UTC|newest]
Thread overview: 87+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-14 9:12 [PATCH tip/core/rcu 0/20] Miscellaneous fixes for 4.11 Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 01/20] rcu: update: Make RCU_EXPEDITE_BOOT be the default Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 02/20] lockdep: Make RCU suspicious-access splats use pr_err Paul E. McKenney
2017-01-16 7:53 ` Josh Triplett
2017-01-17 1:06 ` Paul E. McKenney
2017-01-16 17:21 ` Peter Zijlstra
2017-01-16 20:59 ` Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 03/20] Fix: Disable sys_membarrier when nohz_full is enabled Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 04/20] rcu: Only dump stalled-tasks stacks if there was a real stall Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 05/20] rcu: Remove unneeded rcu_process_callbacks() declarations Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 06/20] rcu: Remove unused but set variable Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 07/20] rcu: Remove short-term CPU kicking Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 08/20] rcu: Add long-term " Paul E. McKenney
2017-01-16 7:58 ` Josh Triplett [this message]
2017-01-17 1:07 ` Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 09/20] rcu: Once again use NMI-based stack traces in stall warnings Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 10/20] rcu: Add functions to test for trivial grace periods Paul E. McKenney
2017-01-16 8:01 ` Josh Triplett
2017-01-17 0:32 ` Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 11/20] sched,rcu: Make cond_resched() provide RCU quiescent state Paul E. McKenney
2017-01-16 8:08 ` Josh Triplett
2017-01-16 11:38 ` Paul E. McKenney
2017-01-16 17:11 ` Peter Zijlstra
2017-01-17 0:54 ` Paul E. McKenney
2017-01-17 10:51 ` Michal Hocko
2017-01-17 12:05 ` Paul E. McKenney
2017-01-17 12:11 ` Michal Hocko
2017-01-18 2:10 ` Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 12/20] rcu: Re-enable TASKS_RCU for User Mode Linux Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 13/20] rcu: Don't wake rcuc/X kthreads on NOCB CPUs Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 14/20] rcu: Add comment headers to expedited-grace-period counter functions Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 15/20] rcu: Make rcu_cpu_starting() use its "cpu" argument Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 16/20] rcu: Enable RCU tracepoints by default to aid in debugging Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 17/20] rcu: Fix comment in rcu_organize_nocb_kthreads() Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 18/20] llist: Clarify comments about when locking is needed Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 19/20] rcu: Eliminate unused expedited_normal counter Paul E. McKenney
2017-01-14 9:13 ` [PATCH tip/core/rcu 20/20] rcu: Add lockdep checks to synchronous expedited primitives Paul E. McKenney
2017-01-16 8:09 ` [PATCH tip/core/rcu 0/20] Miscellaneous fixes for 4.11 Josh Triplett
2017-01-17 1:07 ` Paul E. McKenney
2017-01-18 2:53 ` Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 01/18] rcu: update: Make RCU_EXPEDITE_BOOT be the default Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 02/18] lockdep: Make RCU suspicious-access splats use pr_err Paul E. McKenney
2017-01-21 20:40 ` Josh Triplett
2017-01-23 19:30 ` Paul E. McKenney
2017-01-23 22:33 ` Josh Triplett
2017-01-24 0:13 ` Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 03/18] Fix: Disable sys_membarrier when nohz_full is enabled Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 04/18] rcu: Only dump stalled-tasks stacks if there was a real stall Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 05/18] rcu: Remove unneeded rcu_process_callbacks() declarations Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 06/18] rcu: Remove unused but set variable Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 07/18] rcu: Add long-term CPU kicking Paul E. McKenney
2017-01-21 20:41 ` Josh Triplett
2017-01-21 20:42 ` Josh Triplett
2017-01-23 19:34 ` Paul E. McKenney
2017-01-23 20:25 ` Josh Triplett
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 08/18] rcu: Remove short-term " Paul E. McKenney
2017-01-21 20:43 ` Josh Triplett
2017-01-23 19:36 ` Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 09/18] rcu: Once again use NMI-based stack traces in stall warnings Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 10/18] rcu: Re-enable TASKS_RCU for User Mode Linux Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 11/18] rcu: Don't wake rcuc/X kthreads on NOCB CPUs Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 12/18] rcu: Add comment headers to expedited-grace-period counter functions Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 13/18] rcu: Make rcu_cpu_starting() use its "cpu" argument Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 14/18] rcu: Enable RCU tracepoints by default to aid in debugging Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 15/18] rcu: Fix comment in rcu_organize_nocb_kthreads() Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 16/18] llist: Clarify comments about when locking is needed Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 17/18] rcu: Eliminate unused expedited_normal counter Paul E. McKenney
2017-01-18 2:53 ` [PATCH v2 tip/core/rcu 18/18] rcu: Add lockdep checks to synchronous expedited primitives Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 0/18] Miscellaneous fixes for 4.11 Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 01/18] rcu: update: Make RCU_EXPEDITE_BOOT be the default Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 02/18] lockdep: Make RCU suspicious-access splats use pr_err Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 03/18] Fix: Disable sys_membarrier when nohz_full is enabled Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 04/18] rcu: Only dump stalled-tasks stacks if there was a real stall Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 05/18] rcu: Remove unneeded rcu_process_callbacks() declarations Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 06/18] rcu: Remove unused but set variable Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 07/18] rcu: Add long-term CPU kicking Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 08/18] rcu: Remove short-term " Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 09/18] rcu: Once again use NMI-based stack traces in stall warnings Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 10/18] rcu: Re-enable TASKS_RCU for User Mode Linux Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 11/18] rcu: Don't wake rcuc/X kthreads on NOCB CPUs Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 12/18] rcu: Add comment headers to expedited-grace-period counter functions Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 13/18] rcu: Make rcu_cpu_starting() use its "cpu" argument Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 14/18] rcu: Enable RCU tracepoints by default to aid in debugging Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 15/18] rcu: Fix comment in rcu_organize_nocb_kthreads() Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 16/18] llist: Clarify comments about when locking is needed Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 17/18] rcu: Eliminate unused expedited_normal counter Paul E. McKenney
2017-01-24 21:51 ` [PATCH v3 tip/core/rcu 18/18] rcu: Add lockdep checks to synchronous expedited primitives Paul E. McKenney
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