Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758901AbaGOMHq (ORCPT ); Tue, 15 Jul 2014 08:07:46 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:56795 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758628AbaGOMHn (ORCPT ); Tue, 15 Jul 2014 08:07:43 -0400 Date: Tue, 15 Jul 2014 14:07:28 +0200 From: Peter Zijlstra To: Tim Chen Cc: Herbert Xu , "H. Peter Anvin" , "David S.Miller" , Ingo Molnar , Chandramouli Narayanan , Vinodh Gopal , James Guilford , Wajdi Feghali , Jussi Kivilinna , linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 6/7] sched: add function nr_running_cpu to expose number of tasks running on cpu Message-ID: <20140715120728.GR3588@twins.programming.kicks-ass.net> References: <1405110784.2970.655.camel@schen9-DESK> <20140714101611.GS9918@twins.programming.kicks-ass.net> <1405354214.2970.663.camel@schen9-DESK> <20140714161432.GC9918@twins.programming.kicks-ass.net> <1405357534.2970.701.camel@schen9-DESK> <20140714181738.GI9918@twins.programming.kicks-ass.net> <1405364908.2970.729.camel@schen9-DESK> <20140714191504.GO9918@twins.programming.kicks-ass.net> <1405367450.2970.750.camel@schen9-DESK> <20140715095045.GV9918@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="+S4DbcR7QPeSsP0V" Content-Disposition: inline In-Reply-To: <20140715095045.GV9918@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --+S4DbcR7QPeSsP0V Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Tue, Jul 15, 2014 at 11:50:45AM +0200, Peter Zijlstra wrote: > So you already have an idle notifier (which is x86 only, we should fix > that I suppose), and you then double check there really isn't anything > else running. Note that we've already done a large part of the expense of going idle by the time we call that idle notifier -- in specific, we've reprogrammed the clock to stop the tick. Its really wasteful to then generate work again, which means we have to again reprogram the clock etc. --+S4DbcR7QPeSsP0V Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJTxRmAAAoJEHZH4aRLwOS6PT0P/RMh3e40x8wWWOA2RB+kTNx+ sN9rjgb8LdbOE8DNaPjdGWJMSHfVRHrTX7mLmscRNtMzx4g4r1f/KKWrvY5JJFKl Pgk42SEFkphoe7k+vWlOr7UVhkm3excPaALJDRa/uLh7aTgmeWCBym/g0qwiuc8c eghO466/6uWIDTyu9Cs2WbuT5/eVHD7WXxcf2IL/vEloM1WPAx3bZoklNTx2Tlty +hGnF3YJx/igEaC+5uDKCpMpnQB43jYxGSWA3nq3cutJAsgRxAu/RgdcwObu50JD 92REXd9nUc5Q6jnVQlOUGdD15t37ZbyH2ZPfiWFHKKYw6uE+HxLpCloj/HZwhs1m USs5RtiLOyGDJ1M2hwtXBqI2HJQtK9QYIOuEFSkzX6+ZkRq7/pBHdyEtMXEDaZEw 0XVXF1g7tM4/X0UiUfyp8f3pjbsqxRTHbQ8JJ2OmY+djamkuf06R0ZeT1wyBc5Fp b3BdIqy1Mbs57UihYDWgorkWN3yHQpBzrMrYQhqSqszvT7n/mILokjnOWJXFOrRh 8HKhXehNir74uZeRH7l9+6/La/hTqGYEc1qYzjgJW9Y99u/8zMbK1Q7CKpgMZqYt c0odyCQln8sJq5Wx3K2A3XZuUzKo6w/cihnY3CrRekzc7XkpL2hgvkItIdI03l6I Q7aKMCbfLpK6vYQfvaJi =YwD9 -----END PGP SIGNATURE----- --+S4DbcR7QPeSsP0V-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/