Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932240AbaFKK5k (ORCPT ); Wed, 11 Jun 2014 06:57:40 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:54027 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754032AbaFKK5j (ORCPT ); Wed, 11 Jun 2014 06:57:39 -0400 Date: Wed, 11 Jun 2014 12:57:33 +0200 From: Peter Zijlstra To: Kirill Tkhai Cc: linux-kernel@vger.kernel.org, Ingo Molnar , tkhai@yandex.ru Subject: Re: [PATCH 1/2] sched: Rework migrate_tasks() Message-ID: <20140611105733.GM6758@twins.programming.kicks-ass.net> References: <20140611093417.27807.2288.stgit@tkhai> <1402480330.32126.14.camel@tkhai> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="XZn3P0VKTizxZG2b" Content-Disposition: inline In-Reply-To: <1402480330.32126.14.camel@tkhai> 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 --XZn3P0VKTizxZG2b Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jun 11, 2014 at 01:52:10PM +0400, Kirill Tkhai wrote: >=20 > Currently migrate_tasks() skips throttled tasks, > because they are not pickable by pick_next_task(). >=20 > These tasks stay on dead cpu even after they > becomes unthrottled. They are not schedulable > till user manually changes their affinity or till > cpu becomes alive again. >=20 > But for user this looks completely untransparent: > task hangs, but it's not obvious what he has to do, > because kernel does not report any problem. >=20 > This situation may easily be triggered intentionally. > Playing with extremely small cpu.cfs_quota_us causes > it almost in 100% cases. In usual life it's very rare, > but still possible for some unhappy user. >=20 How about fixing the unthrottle code to validate the affinity? --XZn3P0VKTizxZG2b Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJTmDYcAAoJEHZH4aRLwOS64PcQAIaOBL7z/KHdYEUbP9SItKGU L02yisNuIWajFywwwAiZ+q6CHCQTtcJTVvPdwdcj0Frr5xxjOi/a8++oqtE9RBgi Rab3yviAis8/eTcLMCDOyNQQjkB3MpiUeht2LrwXwUPu1QIAFHTpGRL+8yGdRS5u MCtV/AEH2EzaGTwrAtL5vnAF1tLpj1aokCpotm1lVy9RBuESZZFIBBqhx0wUGWHU VGr/cGPtdWwUk+k08iLcEh42FTFdhNCT9WfnDO/7qqRQL951Xpp4iN3ZiXVheA65 GxKzZZiqwJ7LjvnBRGkh29+PUnDGlb9XsFwt4h5FilGImlb4AWY5x4F4jPhaABoK noQ0qa4VUsaYcQyJ9phvs6ol3cMuJ9yOMX+H52kJNvciakGQtp60VQCLpdjW0QD7 Z5v0DWmr5KG09MPNoc+2jmyl9mqPPQrU6Rp3tkom9aPlEmfF5cEcBlYgFapsxmNg ON4ujUTrUfzFTh4Og6fcc6VXkGshT2M3mIlFSkzXqp0Al9/h9mvSP+p27Cb1whfb +zBaAW5ZXKYWkc5KkwSiBUKIbmFaX6+G/EsL0AaN136KfsqGVF6hgiL9q0AAc0DG zZ0H5d3FvAxBHLTTe56npbnZNloeHXZCcgoH1VjfFoZu9X1PBarVbs2bI3un7Y/U APk82P1jFjqvE2yaTnl7 =hsKO -----END PGP SIGNATURE----- --XZn3P0VKTizxZG2b-- -- 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/