From mboxrd@z Thu Jan 1 00:00:00 1970 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= Subject: Re: [PATCH V5 0/5] Queue work on power efficient wq Date: Mon, 8 Jul 2013 20:55:09 +0200 Message-ID: <20130708185509.GH29556@pengutronix.de> References: <20130708153716.GF29556@pengutronix.de> <20130708155747.GG29556@pengutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: tj@kernel.org, davem@davemloft.net, airlied@redhat.com, axboe@kernel.dk, tglx@linutronix.de, peterz@infradead.org, mingo@redhat.com, rostedt@goodmis.org, linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org, robin.randhawa@arm.com, Steve.Bannister@arm.com, Livi@jasper.es To: Viresh Kumar Return-path: Received: from metis.ext.pengutronix.de ([92.198.50.35]:59888 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751984Ab3GHSz2 (ORCPT ); Mon, 8 Jul 2013 14:55:28 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-rt-users-owner@vger.kernel.org List-ID: Hello, On Mon, Jul 08, 2013 at 10:18:08PM +0530, Viresh Kumar wrote: > On 8 July 2013 21:27, Uwe Kleine-K=F6nig wrote: > > On Mon, Jul 08, 2013 at 09:17:01PM +0530, Viresh Kumar wrote: >=20 > >> Well, big LITTLE still runs an SMP kernel :) and so has this flag = set. > > The 'S' is justified because cpu0 and cpu1 are of the same type? Ar= e > > there b.L systems that have only one big and one LITTLE cpu? Do the= se > > use SMP, too? >=20 > Following definition of SMP says: > http://en.wikipedia.org/wiki/Symmetric_Multiprocessor >=20 > A system is SMP when: > - It has same type of cores > - controlled by a single instance of OS. >=20 > In big LITTLE first one is obviously not completely true as you point= ed out. > But second one is and so I would say its an SMP system :) >=20 > Don't know how it should be called though. MP maybe. > >> You can make it dependent on that if required. > > Well, it's not required. It's just that the corresponding question = in > > make oldconfig isn't really an enrichment for a kernel targeting an > > Cortex M3 :-) >=20 > Just to make it clear enough, you are saying it doesn't make any > sense to enable it for M3? But because it is disabled by default, > the problem is not seen? No I'm saying that asking me is bad because on an UP machine it won't matter what I answer. So please don't ask me if SMP is off. > Why? Can't we have two M3's on a SoC and run an SMP kernel over > it? Yeah, you can. Then you'd have SMP (or MP) enabled though and the choic= e for that workqueue thing makes a difference. In that case asking is OK. Best regards Uwe --=20 Pengutronix e.K. | Uwe Kleine-K=F6nig = | Industrial Linux Solutions | http://www.pengutronix.de/= | -- To unsubscribe from this list: send the line "unsubscribe linux-rt-user= s" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html