From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764525AbXHFLIG (ORCPT ); Mon, 6 Aug 2007 07:08:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1764368AbXHFLHB (ORCPT ); Mon, 6 Aug 2007 07:07:01 -0400 Received: from hu-out-0506.google.com ([72.14.214.230]:40606 "EHLO hu-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1764307AbXHFLHA (ORCPT ); Mon, 6 Aug 2007 07:07:00 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:user-agent:mime-version:to:cc:subject:references:in-reply-to:content-type:content-transfer-encoding; b=tjUU+Jo+aW5pdILdmgf/dpLkwjovPfOMUHmSuFOQmne8T8L3pUmG25RV8tpnqICvClIWxBco6cE4OZ5niPH7oOHLE4QVoz8Bq+jsNFDQ0Oq4Z50Qn3w/Cdi7TyL1ezvXS3YW0w4+zzEYY9PGIA8y00jDx3xfrOAATuGUx0e+pa0= Message-ID: <46B700C7.5090801@gmail.com> Date: Mon, 06 Aug 2007 13:06:47 +0200 From: dragoran User-Agent: Thunderbird 2.0.0.5 (X11/20070719) MIME-Version: 1.0 To: Andi Kleen CC: linux-kernel@vger.kernel.org Subject: Re: allow non root users to set io priority "idle" ? References: <46B6EDCB.6030806@gmail.com> <46B6F75D.1070808@gmail.com> <20070806103553.GA16133@one.firstfloor.org> In-Reply-To: <20070806103553.GA16133@one.firstfloor.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andi Kleen wrote: >> couldn't this be fixed by bumping idle tasks to middle while they hold a >> > > Usually to high. > > But it's all complicated and hasn't been done consistently > (there are real time mutexes in the -rt kernel for example, > but there are lots of other locks and they have higher overhead too) > and it's unclear we really want to do all this complexity anyways. > > Also as I said the problem could then still happen in user space > which then would all need to be fixed to handle PI too. > > In some cases the relationship is also not as simple as a single > lock. And for IO handling it would be likely quite hard. > > I personally always found idle priorities quite dubious because > even if they worked reliable for the CPU they will clear your cache/ > load your memory controller and impact all other programs because > of this. And for the disk they will cause additional seeks which are > also very costly. > > ok, thx so that means that the best that can be done for now is to run beagle as best effort with prio 7 (like its done now).