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Groups > linux.kernel > #1564241
| From | Josh Triplett <josh@joshtriplett.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH v2 tip/core/rcu 07/18] rcu: Add long-term CPU kicking |
| Date | 2017-01-21 21:50 +0100 |
| Message-ID | <t2aLM-8sX-13@gated-at.bofh.it> (permalink) |
| References | <t0ODD-6Iu-3@gated-at.bofh.it> <t0RBw-oA-27@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Tue, Jan 17, 2017 at 06:53:46PM -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.
Just realized an issue with this commit message: you're referring to
what now appears as patch 8 in the past tense as something already done,
and with a commit ID that probably doesn't work anymore. You need to
rephrase this to describe how it leads to a *subsequent* change rather
than fixing something already changed.
With the commit message fixed:
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> ---
> kernel/rcu/tree.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index 83bf054e194e..0e61b62e3f4a 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -1225,6 +1225,12 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp,
> rdp->rsp->gp_start + 2 * jiffies_till_sched_qs) ||
> ULONG_CMP_GE(jiffies, rdp->rsp->gp_start + jiffies_till_sched_qs))
> resched_cpu(rdp->cpu); /* Force CPU into scheduler. */
> + /*
> + * 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
>
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Re: [PATCH tip/core/rcu 0/20] Miscellaneous fixes for 4.11 "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-18 04:00 +0100
[PATCH v2 tip/core/rcu 01/18] rcu: update: Make RCU_EXPEDITE_BOOT be the default "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-18 04:00 +0100
[PATCH v2 tip/core/rcu 14/18] rcu: Enable RCU tracepoints by default to aid in debugging "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-18 04:00 +0100
[PATCH v2 tip/core/rcu 08/18] rcu: Remove short-term CPU kicking "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-18 04:00 +0100
Re: [PATCH v2 tip/core/rcu 08/18] rcu: Remove short-term CPU kicking Josh Triplett <josh@joshtriplett.org> - 2017-01-21 21:50 +0100
Re: [PATCH v2 tip/core/rcu 08/18] rcu: Remove short-term CPU kicking "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-23 20:40 +0100
[PATCH v2 tip/core/rcu 11/18] rcu: Don't wake rcuc/X kthreads on NOCB CPUs "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-18 04:10 +0100
[PATCH v2 tip/core/rcu 15/18] rcu: Fix comment in rcu_organize_nocb_kthreads() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-18 04:30 +0100
[PATCH v2 tip/core/rcu 06/18] rcu: Remove unused but set variable "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-18 04:40 +0100
[PATCH v2 tip/core/rcu 13/18] rcu: Make rcu_cpu_starting() use its "cpu" argument "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-18 04:40 +0100
[PATCH v2 tip/core/rcu 18/18] rcu: Add lockdep checks to synchronous expedited primitives "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-18 05:00 +0100
[PATCH v2 tip/core/rcu 03/18] Fix: Disable sys_membarrier when nohz_full is enabled "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-18 05:40 +0100
[PATCH v2 tip/core/rcu 12/18] rcu: Add comment headers to expedited-grace-period counter functions "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-18 05:50 +0100
[PATCH v2 tip/core/rcu 17/18] rcu: Eliminate unused expedited_normal counter "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-18 05:50 +0100
[PATCH v2 tip/core/rcu 16/18] llist: Clarify comments about when locking is needed "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-18 06:20 +0100
[PATCH v2 tip/core/rcu 02/18] lockdep: Make RCU suspicious-access splats use pr_err "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-18 06:40 +0100
Re: [PATCH v2 tip/core/rcu 02/18] lockdep: Make RCU suspicious-access splats use pr_err Josh Triplett <josh@joshtriplett.org> - 2017-01-21 21:50 +0100
Re: [PATCH v2 tip/core/rcu 02/18] lockdep: Make RCU suspicious-access splats use pr_err "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-23 20:40 +0100
Re: [PATCH v2 tip/core/rcu 02/18] lockdep: Make RCU suspicious-access splats use pr_err Josh Triplett <josh@joshtriplett.org> - 2017-01-23 23:40 +0100
Re: [PATCH v2 tip/core/rcu 02/18] lockdep: Make RCU suspicious-access splats use pr_err "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-24 01:20 +0100
[PATCH v2 tip/core/rcu 05/18] rcu: Remove unneeded rcu_process_callbacks() declarations "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-18 07:10 +0100
[PATCH v2 tip/core/rcu 07/18] rcu: Add long-term CPU kicking "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-18 07:10 +0100
Re: [PATCH v2 tip/core/rcu 07/18] rcu: Add long-term CPU kicking Josh Triplett <josh@joshtriplett.org> - 2017-01-21 21:50 +0100
Re: [PATCH v2 tip/core/rcu 07/18] rcu: Add long-term CPU kicking "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-23 20:40 +0100
Re: [PATCH v2 tip/core/rcu 07/18] rcu: Add long-term CPU kicking Josh Triplett <josh@joshtriplett.org> - 2017-01-23 21:30 +0100
Re: [PATCH v2 tip/core/rcu 07/18] rcu: Add long-term CPU kicking Josh Triplett <josh@joshtriplett.org> - 2017-01-21 21:50 +0100
[PATCH v3 tip/core/rcu 0/18] Miscellaneous fixes for 4.11 "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-24 23:00 +0100
[PATCH v3 tip/core/rcu 17/18] rcu: Eliminate unused expedited_normal counter "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-24 23:00 +0100
[PATCH v3 tip/core/rcu 04/18] rcu: Only dump stalled-tasks stacks if there was a real stall "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-24 23:00 +0100
[PATCH v3 tip/core/rcu 16/18] llist: Clarify comments about when locking is needed "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-24 23:00 +0100
[PATCH v3 tip/core/rcu 06/18] rcu: Remove unused but set variable "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-24 23:00 +0100
[PATCH v3 tip/core/rcu 05/18] rcu: Remove unneeded rcu_process_callbacks() declarations "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-24 23:00 +0100
[PATCH v3 tip/core/rcu 02/18] lockdep: Make RCU suspicious-access splats use pr_err "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-24 23:00 +0100
[PATCH v3 tip/core/rcu 12/18] rcu: Add comment headers to expedited-grace-period counter functions "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-24 23:00 +0100
[PATCH v3 tip/core/rcu 14/18] rcu: Enable RCU tracepoints by default to aid in debugging "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-24 23:00 +0100
[PATCH v3 tip/core/rcu 07/18] rcu: Add long-term CPU kicking "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-24 23:00 +0100
[PATCH v3 tip/core/rcu 18/18] rcu: Add lockdep checks to synchronous expedited primitives "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-24 23:00 +0100
[PATCH v3 tip/core/rcu 11/18] rcu: Don't wake rcuc/X kthreads on NOCB CPUs "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-24 23:00 +0100
[PATCH v3 tip/core/rcu 13/18] rcu: Make rcu_cpu_starting() use its "cpu" argument "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-24 23:00 +0100
[PATCH v3 tip/core/rcu 10/18] rcu: Re-enable TASKS_RCU for User Mode Linux "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-24 23:00 +0100
[PATCH v3 tip/core/rcu 15/18] rcu: Fix comment in rcu_organize_nocb_kthreads() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-01-24 23:00 +0100
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