From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bernhard Schmidt Subject: hugetlbfs and KSM Date: Thu, 8 Apr 2010 19:29:03 +0000 (UTC) Message-ID: To: kvm@vger.kernel.org Return-path: Received: from lo.gmane.org ([80.91.229.12]:39694 "EHLO lo.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933354Ab0DHT3O (ORCPT ); Thu, 8 Apr 2010 15:29:14 -0400 Received: from list by lo.gmane.org with local (Exim 4.69) (envelope-from ) id 1NzxPc-0004BL-GD for kvm@vger.kernel.org; Thu, 08 Apr 2010 21:29:12 +0200 Received: from ppp-88-217-17-22.dynamic.mnet-online.de ([88.217.17.22]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Thu, 08 Apr 2010 21:29:12 +0200 Received: from berni by ppp-88-217-17-22.dynamic.mnet-online.de with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Thu, 08 Apr 2010 21:29:12 +0200 Sender: kvm-owner@vger.kernel.org List-ID: Hi, running Debian Squeeze with a 2.6.32-3-amd64 kernel and qemu-kvm 0.12.3 I enabled hugetlbfs on a rather small box with about five similar VMs today (all Debian Squeeze amd64, but different services) Pro: * system load on the host has gone way down (by about 50%) Contra: * KSM seems to be largely ineffective (100MB saved -> 1.3MB saved) Am I doing something wrong? Is this a bug? Is this generally impossible with large pages (which might explain the lower load on the host, if large pages are not scanned)? Or is it just way less likely to have identical pages at that size? Bernhard