From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f198.google.com (mail-pf0-f198.google.com [209.85.192.198]) by kanga.kvack.org (Postfix) with ESMTP id 2C7206B007E for ; Fri, 15 Apr 2016 15:15:51 -0400 (EDT) Received: by mail-pf0-f198.google.com with SMTP id u190so203453454pfb.0 for ; Fri, 15 Apr 2016 12:15:51 -0700 (PDT) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id lq6si5690740pab.140.2016.04.15.12.15.50 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 15 Apr 2016 12:15:50 -0700 (PDT) Date: Fri, 15 Apr 2016 12:15:49 -0700 From: Andrew Morton Subject: Re: [Bug 107771] New: Single process tries to use more than 1/2 physical RAM, OS starts thrashing Message-Id: <20160415121549.47e404e3263c71564929884e@linux-foundation.org> In-Reply-To: References: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: bugzilla-daemon@bugzilla.kernel.org, Rik van Riel , Johannes Weiner , Mel Gorman , theosib@gmail.com (switched to email. Please respond via emailed reply-to-all, not via the bugzilla web interface). This is ... interesting. On Thu, 12 Nov 2015 18:46:35 +0000 bugzilla-daemon@bugzilla.kernel.org wrote: > https://bugzilla.kernel.org/show_bug.cgi?id=107771 > > Bug ID: 107771 > Summary: Single process tries to use more than 1/2 physical > RAM, OS starts thrashing > Product: Memory Management > Version: 2.5 > Kernel Version: 4.3.0-040300-generic (Ubuntu) > Hardware: All > OS: Linux > Tree: Mainline > Status: NEW > Severity: normal > Priority: P1 > Component: Page Allocator > Assignee: akpm@linux-foundation.org > Reporter: theosib@gmail.com > Regression: No > > I have a 24-core (48 thread) system with 64GB of RAM. > > When I run multiple processes, I can use all of physical RAM before swapping > starts. However, if I'm running only a *single* process, the system will start > swapping after I've exceeded only 1/2 of available physical RAM. Only after > swap fills does it start using more of the physical RAM. > > I can't find any ulimit settings or anything else that would cause this to > happen intentionally. > > I had originally filed this against Ubuntu, but I'm now running a more recent > kernel, and the problem persists, so I think it's more appropriate to file > here. There are some logs that they had me collect, so if you want to see > them, the are here: > > https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1513673 > > I don't recall this problem happening with older kernels (whatever came with > Ubuntu 15.04), although I may just not have noticed. By swapping early, I'm > limited by the speed of my SSD, which is moving only about 20MB/sec in each > direction, and that makes what I'm running take 10 times as long to complete. > > -- > You are receiving this mail because: > You are the assignee for the bug. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org