From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755934Ab1ISRwT (ORCPT ); Mon, 19 Sep 2011 13:52:19 -0400 Received: from mx1.redhat.com ([209.132.183.28]:16951 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755708Ab1ISRwP (ORCPT ); Mon, 19 Sep 2011 13:52:15 -0400 Date: Mon, 19 Sep 2011 19:51:59 +0200 From: Andrea Arcangeli To: Lin Ming Cc: fa.linux.kernel@googlegroups.com, slawomir.czarko@gmail.com, Linux Kernel Mailing List , Thomas Sattler , Johannes Weiner , Mel Gorman Subject: Re: iotop: khugepaged at 99.99% (2.6.38.3) Message-ID: <20110919175159.GL7800@redhat.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 15, 2011 at 02:43:32PM +0800, Lin Ming wrote: > # cat /proc/`pgrep khugepaged`/io > rchar: 0 > wchar: 0 > syscr: 0 > syscw: 0 > read_bytes: 0 > write_bytes: 0 > cancelled_write_bytes: 0 > > Andrea, > > From above output, all fields are zero. > Does it mean that transparent huge page was not triggered/used at all? Good idea to check it like that, yes that should confirm no ->writepage was called by khugepaged through compaction->migrate->writepage. It may have been used for migration, but the compaction code run by khugepaged didn't trigger writes, or the write_bytes should have been > 0. With regard to Slawomir's problem, the kernel kernel-PAE-2.6.40.4-5.fc15.i686 includes Mel's fix for the compaction scan to stay in the right zone. Slawomir could you run the command "cat /proc/`pgrep khugepaged`/io" as root, so see if there's significant writeout going from khugepaged? If there is you can try the patch in the below link. https://lkml.org/lkml/2011/7/26/103 But the fact it happens on top of VMplayer with a PAE guest, may also be a variable to take into account, migrate does quite some pagetable work. If VMplayer uses EPT/NTP (do you have EPT/NTP available as VT feature in the host /proc/cpuinfo?) it's hard to see how that could be related.