From: Frederic Weisbecker <fweisbec@gmail.com>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Josh Triplett <josh@joshtriplett.org>,
Steven Rostedt <rostedt@goodmis.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Subject: Re: [PATCH] rcu: Only pin GP kthread when full dynticks is actually used
Date: Fri, 13 Jun 2014 18:21:32 +0200 [thread overview]
Message-ID: <20140613162130.GP6635@localhost.localdomain> (raw)
In-Reply-To: <20140613161630.GQ4581@linux.vnet.ibm.com>
On Fri, Jun 13, 2014 at 09:16:30AM -0700, Paul E. McKenney wrote:
> > Is it because we have dynticks CPUs staying too long in the kernel without
> > taking any quiescent states? Are we perhaps missing some rcu_user_enter() or
> > things?
>
> Sort of the former, but combined with the fact that in-kernel CPUs still
> need scheduling-clock interrupts for RCU to make progress. I could
> move this to RCU's context-switch hook, but that could be very bad for
> workloads that do lots of context switching.
Or I can restart the tick if the CPU stays in the kernel for too long without
a tick. I think that's what we were doing before but we removed that because
we never implemented it correctly (we sent scheduler IPI that did nothing...)
next prev parent reply other threads:[~2014-06-13 16:21 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-13 0:16 [PATCH] rcu: Only pin GP kthread when full dynticks is actually used Frederic Weisbecker
2014-06-13 1:24 ` Paul E. McKenney
2014-06-13 1:35 ` Paul E. McKenney
2014-06-13 12:47 ` Frederic Weisbecker
2014-06-13 15:52 ` Paul E. McKenney
2014-06-13 16:00 ` Frederic Weisbecker
2014-06-13 16:16 ` Paul E. McKenney
2014-06-13 16:21 ` Frederic Weisbecker [this message]
2014-06-13 16:44 ` Josh Triplett
2014-06-13 20:48 ` Paul E. McKenney
2014-06-13 21:10 ` Josh Triplett
2014-06-13 22:49 ` Paul E. McKenney
2014-06-13 23:10 ` Frederic Weisbecker
2014-06-13 23:27 ` Paul E. McKenney
2014-06-13 23:39 ` Frederic Weisbecker
2014-06-14 5:06 ` Paul E. McKenney
2014-06-14 11:26 ` Paul E. McKenney
2014-06-14 13:10 ` Frederic Weisbecker
2014-06-14 14:29 ` Paul E. McKenney
2014-06-14 13:05 ` Frederic Weisbecker
2014-06-13 20:49 ` Paul E. McKenney
2014-06-13 23:13 ` Frederic Weisbecker
2014-06-13 23:22 ` Paul E. McKenney
2014-06-13 2:05 ` Paul E. McKenney
2014-06-13 12:55 ` Frederic Weisbecker
2014-06-13 15:55 ` Paul E. McKenney
2014-06-13 16:03 ` Frederic Weisbecker
2014-06-13 16:20 ` Paul E. McKenney
2014-06-13 16:10 ` Paul E. McKenney
2014-06-13 12:42 ` Frederic Weisbecker
2014-06-13 15:58 ` Paul E. McKenney
2014-06-13 16:09 ` Frederic Weisbecker
2014-06-13 16:23 ` Paul E. McKenney
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