From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933730AbXHHKEx (ORCPT ); Wed, 8 Aug 2007 06:04:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932518AbXHHKDO (ORCPT ); Wed, 8 Aug 2007 06:03:14 -0400 Received: from thb8.jinr.ru ([159.93.129.8]:50979 "EHLO theor.jinr.ru" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932487AbXHHKDM (ORCPT ); Wed, 8 Aug 2007 06:03:12 -0400 X-Greylist: delayed 695 seconds by postgrey-1.27 at vger.kernel.org; Wed, 08 Aug 2007 06:03:12 EDT Date: Wed, 8 Aug 2007 13:51:32 +0400 To: Andi Kleen Cc: dragoran , linux-kernel@vger.kernel.org Subject: Re: allow non root users to set io priority "idle" ? Message-ID: <20070808095132.GA31020@theor.jinr.ru> References: <46B6EDCB.6030806@gmail.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="sdtB3X0nJg68CQEu" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.13 (2006-08-11) From: varg@theor.jinr.ru (Sheplyakov Alexei) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org --sdtB3X0nJg68CQEu Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Aug 06, 2007 at 01:11:01PM +0200, Andi Kleen wrote: > Very low priority can starve others when it holds some kernel resource > needed by another task. =20 Nevertheless ordinary users are permitted to lower priority ([re]nice) and resource limits (setrlimit). > For IO I suppose the same could happen too. e.g. low priority > task wants to write out a page and keeps it locked until the IO=20 > is finished. High priority task wants to access the page and has > to wait until it is unlocked. Middle task generates an endless > stream of IO that makes the idle priority writeout never finish. I don't quite understand. There are a lot of other ways to starve such high-priority process:=20 1. renice the low-priority process 2. send it a signal 3. ptrace it 4. use something like cpulimit (http://cpulimit.sourceforge.net/) to stall = it =2E... So I think current behaviour of ionice is inconsistent (and pointless). P.S.=20 Please CC me, I'm not subscribed. Best regards, Alexei --=20 All science is either physics or stamp collecting. --sdtB3X0nJg68CQEu Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iQIVAwUBRrmSIyXMWnuYxRVqAQKZaA//cCN26rGNiu0y4u+gCe/y/5zUzrn8AiIl zjkriUMLFVnjqJkKlkB1XAR1SpLMd1bzyJpTDlNmfadcBbyXBgq+R5Iek/ZU/4So Kh0VKNUbYWCc2QBjQI+YT0Jnykbh++w4XqamV076QXoC02bt3hBqY5wTQpzocxp+ CL/yjtBSg77IEDCEuWpc3pSMlS3HLkpJZU23GrkPPGnxeVa5I1Q+O5LkYemsDII8 RBHHMCUP+aFjTyG81y6scOapDuJrbof4eH/qeOMKfcdf+qFzWyGkJTaD869eUUbf ojsZUdjJ3ZVEIaupAW3Tr3/+xwy286qQwgMvdr8TPjKH/zyqQ02X4w4sMVzvl5aA E6tntEGh3+hRAbK5Qs++r9rq+De4unqhfltAzg7rCTS8pXkuDASEL7h0jGeqwHlK FZs9GSk80ptowN2At77Me3S5JJ8rCSrF4kjnxj9eSYbqhlqJvgEnZDRFTdQwmeoJ VMqkWZGcEZNuEI6k0ldCSCtg/grIyohH3utH6Uvnz1H3LCm5TCOc3MvhVYpHuuZI PkF6QV6eRoRDqpf86GL10K3jyJvl/MTsbNN6qd66cXn/jTiV9sd/J4vIEuWIH/Pz oirUvveYL5GKsYucLME3TIxOIzB2saO+VD3c0THR2QWJ2Wb08gnFODdlDxo4xPbh ozPW3lToJK8= =+fiB -----END PGP SIGNATURE----- --sdtB3X0nJg68CQEu--