From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752785AbeD3KAU (ORCPT ); Mon, 30 Apr 2018 06:00:20 -0400 Received: from smtp.radex.nl ([178.250.146.7]:47922 "EHLO radex-web.radex.nl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751308AbeD3KAT (ORCPT ); Mon, 30 Apr 2018 06:00:19 -0400 From: Ferry Toth To: Alan Cox Cc: Mike Galbraith , linux-kernel@vger.kernel.org Subject: Re: DOS by unprivileged user Date: Mon, 30 Apr 2018 12:00:16 +0200 Message-ID: <12218300.6oQjICIiUq@ferry-quad> In-Reply-To: <20180425155459.5a4e40e0@alans-desktop> References: <9023506.UBh6vynRGa@delfion> <1524470676.5451.1.camel@gmx.de> <20180425155459.5a4e40e0@alans-desktop> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by mail.home.local id w3UA0QHT011882 Op woensdag 25 april 2018 16:54:59 CEST schreef Alan Cox: > > > I think memory allocation and io waits can't be decoupled from > > > scheduling as they are now. > > > > The scheduler is not decoupled from either, it is intimately involved > > in both. However, none of the decision making smarts for either reside > > in the scheduler, nor should they. > > It belongs in both. > > Classical Unix systems never had this problem because they respond to > thrashing by ensuring that all processes consumed CPU and made some > progress. Linux handles it by thrashing itself to dealth while BSD always > handled it by moving from paging more towards swapping and behaving like > a swap bound batch machine. > > Linux thrashes itself to death, the classic BSD algorithn instead throws > fairness out of the window under extreme load to prevent it. It might take > a few seconds but at least you will get your prompt back. > > Alan > I havent tried BSD. But when I was young I allocated 10MB on a HP9000 (UX) with 1MB of RAM. People wanted to launch me out of the window (18th floor). I did not want to say Unix was better, only with so much emphasis on security I'm surprised how easy it is for a regular user to bring linux to on its knees.