From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753048AbaGGWuU (ORCPT ); Mon, 7 Jul 2014 18:50:20 -0400 Received: from terminus.zytor.com ([198.137.202.10]:59947 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750976AbaGGWuS (ORCPT ); Mon, 7 Jul 2014 18:50:18 -0400 Message-ID: <53BB240C.30400@zytor.com> Date: Mon, 07 Jul 2014 15:49:48 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: Andi Kleen , torvalds@linux-foundation.org CC: linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: fallout of 16K stacks References: <20140707223001.GD18735@two.firstfloor.org> In-Reply-To: <20140707223001.GD18735@two.firstfloor.org> X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/07/2014 03:30 PM, Andi Kleen wrote: > > Since the 16K stack change I noticed a number of problems with > my usual stress tests. They have a tendency to bomb out > because something cannot fork. As in ENOMEM or does something worse happen? > - AIM7 on a dual socket socket system now cannot reliably run >> 1000 parallel jobs. ... with how much RAM? > - LTP stress + memhog stress in parallel to something else > usually doesn't survive the night. > > Do we need to strengthen the memory allocator to try > harder for 16K? Can we even? The probability of success goes down exponentially in the order requested. Movable pages can help, of course, but still, there is a very real cost to this :( -hpa