From: Peter Zijlstra <peterz@infradead.org>
To: Andi Kleen <andi@firstfloor.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
linux-kernel@vger.kernel.org, mingo@elte.hu,
laijs@cn.fujitsu.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca,
josh@joshtriplett.org, dvhltc@us.ibm.com, niv@us.ibm.com,
tglx@linutronix.de, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu,
dhowells@redhat.com
Subject: Re: [PATCH RFC tip/core/rcu] accelerate grace period if last non-dynticked CPU
Date: Wed, 27 Jan 2010 10:50:50 +0100 [thread overview]
Message-ID: <1264585850.4283.1992.camel@laptop> (raw)
In-Reply-To: <20100127094336.GA12522@basil.fritz.box>
On Wed, 2010-01-27 at 10:43 +0100, Andi Kleen wrote:
>
> Can't you simply check that at runtime then?
>
> if (num_possible_cpus() > 20)
> ...
>
> BTW the new small is large. This years high end desktop PC will come with
> upto 12 CPU threads. It would likely be challenging to find a good
> number for 20 that holds up with the future.
If only scalability were that easy :/
These massive core/thread count things are causing more problems as
well, the cpus/node ratios are constantly growing, giving grief in the
page allocator as well as other places that used to scale per node.
As to the current problem, the call_rcu() interface doesn't make a hard
promise that the callback will be done on the same cpu, right? So why
not simply move the callback list over to a more active cpu?
next prev parent reply other threads:[~2010-01-27 9:51 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-25 3:48 [PATCH RFC tip/core/rcu] accelerate grace period if last non-dynticked CPU Paul E. McKenney
2010-01-25 12:28 ` Lai Jiangshan
2010-01-25 12:35 ` Peter Zijlstra
2010-01-25 15:08 ` Steven Rostedt
2010-01-27 5:17 ` Paul E. McKenney
2010-01-25 15:12 ` Steven Rostedt
2010-01-27 14:11 ` Paul E. McKenney
2010-01-27 14:52 ` Steven Rostedt
2010-01-26 21:30 ` Andi Kleen
2010-01-26 23:55 ` Mathieu Desnoyers
2010-01-27 5:21 ` Paul E. McKenney
2010-01-27 5:20 ` Paul E. McKenney
2010-01-27 9:43 ` Andi Kleen
2010-01-27 9:50 ` Peter Zijlstra [this message]
2010-01-27 10:00 ` Andi Kleen
2010-01-27 10:04 ` Paul E. McKenney
2010-01-27 11:39 ` Nick Piggin
2010-01-27 11:59 ` Paul E. McKenney
2010-01-27 10:01 ` Paul E. McKenney
2010-01-27 10:13 ` Andi Kleen
2010-01-27 11:44 ` Paul E. McKenney
2010-01-27 12:11 ` Andi Kleen
2010-01-27 13:23 ` Paul E. McKenney
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