From: Steven Rostedt <rostedt@goodmis.org>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Lai Jiangshan <jiangshanlai@gmail.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Josh Triplett <josh@joshtriplett.org>,
stable <stable@vger.kernel.org>
Subject: Re: [PATCH] Fix: disable sys_membarrier when nohz_full is enabled
Date: Thu, 17 Nov 2016 09:50:11 -0500 [thread overview]
Message-ID: <20161117095011.1857bca5@gandalf.local.home> (raw)
In-Reply-To: <11301812.5114.1479390867218.JavaMail.zimbra@efficios.com>
On Thu, 17 Nov 2016 13:54:27 +0000 (UTC)
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:
> >> >
> >> > Acked-by: Lai Jiangshan <jiangshanlai@gmail.com>
> >> >
> >> > But I'm afraid, in the future, tick_nohz_full will become a default y
> >> > feature. thus it makes sys_membarrier() always disabled. we might
> >> > need a new MEMBARRIER_CMD_XXX to handle it?
> >>
> >> This may require that we send an IPI to nohz_full CPUs, which will
> >> disturb them real-time wise. Any better ideas ?
> >
> > Restrict the IPIs to CPUs running the process executing the
> > sys_membarrier() system call. This would mean that CPUs only
> > are interrupted by their own application's request.
>
> This would break use-cases of cross-process shared memory. :-(
Perhaps make this an opt in. That is, all processes that want to be
affected by this can call this function with some flag that sets a flag
in tasks struct. And have that process get an IPI even in no-hz-full
mode if it asked to do it.
-- Steve
next prev parent reply other threads:[~2016-11-17 18:29 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-03 16:29 [PATCH] Fix: disable sys_membarrier when nohz_full is enabled Mathieu Desnoyers
2016-11-03 17:49 ` Paul E. McKenney
2016-11-07 17:08 ` Mathieu Desnoyers
2016-11-07 18:06 ` Paul E. McKenney
2016-11-07 18:10 ` Mathieu Desnoyers
2016-11-07 20:03 ` Paul E. McKenney
2016-11-08 11:15 ` Mathieu Desnoyers
2016-11-12 17:58 ` Paul E. McKenney
2016-11-17 6:51 ` Lai Jiangshan
2016-11-17 11:46 ` Mathieu Desnoyers
2016-11-17 13:40 ` Paul E. McKenney
2016-11-17 13:54 ` Mathieu Desnoyers
2016-11-17 14:09 ` Paul E. McKenney
2016-11-17 14:50 ` Steven Rostedt [this message]
2016-11-17 15:02 ` Mathieu Desnoyers
2016-11-17 15:17 ` Steven Rostedt
2016-11-17 16:02 ` Paul E. McKenney
2016-11-17 13:38 ` Paul E. McKenney
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