From: Arjan van de Ven <arjan@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: paulmck@linux.vnet.ibm.com, linux-kernel@vger.kernel.org,
mingo@kernel.org, laijs@cn.fujitsu.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, dvhart@linux.intel.com,
fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com
Subject: Re: [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods
Date: Fri, 20 Feb 2015 09:45:39 -0800 [thread overview]
Message-ID: <54E772C3.30508@linux.intel.com> (raw)
In-Reply-To: <20150220174359.GW5029@twins.programming.kicks-ass.net>
On 2/20/2015 9:43 AM, Peter Zijlstra wrote:
> On Fri, Feb 20, 2015 at 09:32:39AM -0800, Arjan van de Ven wrote:
>> there's a few others as well that I'm chasing down...
>> .. but the flip side, prior to running ring 3 code, why NOT do fast expedites?
>
> So my objections are twofold:
>
> - I object to fast expedites in principle; they spray IPIs across the
> system, so ideally we'd not have them at all, therefore also not at
> boot.
>
> Because as soon as the option exists, people will use it for other
> things too.
the option exists today in sysfs and kernel parameter...
>
> And esp. in bootup code you can special case a lot of stuff; there's
> limited concurrency esp. because userspace it not there yet. So we might
> not actually need those sync calls.
yeah I am going down that angle as well absolutely.
but there are cases that may well be legit (or are 5 function calls deep into common code)
next prev parent reply other threads:[~2015-02-20 17:45 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-20 5:08 [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods Paul E. McKenney
2015-02-20 5:09 ` [PATCH v2 RFC tip/core/rcu 1/4] rcu: Provide rcu_expedite_gp() and rcu_unexpedite_gp() Paul E. McKenney
2015-02-20 5:09 ` [PATCH v2 RFC tip/core/rcu 2/4] rcu: Add rcu_expedite_gp() and rcu_unexpedite_gp() to rcutorture Paul E. McKenney
2015-02-20 5:09 ` [PATCH v2 RFC tip/core/rcu 3/4] rcu: Update from rcu_expedited variable to rcu_gp_is_expedited() Paul E. McKenney
2015-02-20 5:09 ` [PATCH v2 RFC tip/core/rcu 4/4] rcu: Add Kconfig option to expedite grace periods during boot Paul E. McKenney
2015-02-20 9:11 ` [PATCH tip/core/rcu 0/4] Programmatic nestable expedited grace periods Peter Zijlstra
2015-02-20 16:37 ` Paul E. McKenney
2015-02-20 16:54 ` Peter Zijlstra
2015-02-20 17:14 ` Paul E. McKenney
2015-02-20 17:32 ` Arjan van de Ven
2015-02-20 17:43 ` Peter Zijlstra
2015-02-20 17:45 ` Arjan van de Ven [this message]
2015-02-21 16:08 ` Peter Zijlstra
2015-02-22 1:43 ` Paul E. McKenney
2015-02-20 18:38 ` Paul E. McKenney
2015-02-21 16:11 ` Peter Zijlstra
2015-02-21 17:59 ` Paul E. McKenney
2015-02-20 18:27 ` Paul E. McKenney
2015-02-20 18:29 ` Arjan van de Ven
2015-02-20 18:39 ` Paul E. McKenney
2015-02-21 15:51 ` Arjan van de Ven
2015-02-21 18:00 ` Paul E. McKenney
2015-02-22 3:58 ` Josh Triplett
2015-02-22 6:10 ` Paul E. McKenney
2015-02-22 18:31 ` Arjan van de Ven
2015-02-22 18:48 ` Josh Triplett
2015-02-21 6:04 ` Josh Triplett
2015-02-21 15:12 ` Mathieu Desnoyers
2015-02-21 23:58 ` Paul E. McKenney
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