From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756937Ab2AKLTp (ORCPT ); Wed, 11 Jan 2012 06:19:45 -0500 Received: from mail-qy0-f174.google.com ([209.85.216.174]:51283 "EHLO mail-qy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753905Ab2AKLTo (ORCPT ); Wed, 11 Jan 2012 06:19:44 -0500 Message-ID: <1326280780.2767.11.camel@edumazet-HP-Compaq-6005-Pro-SFF-PC> Subject: RE: Extermeley large PageTables over 500G on kernel 2.6.32.49 (SLES11 SP1) From: Eric Dumazet To: "Borzenkov, Andrey" Cc: "linux-kernel@vger.kernel.org" Date: Wed, 11 Jan 2012 12:19:40 +0100 In-Reply-To: References: <1326278196.2767.7.camel@edumazet-HP-Compaq-6005-Pro-SFF-PC> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.1- Content-Transfer-Encoding: 8bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le mercredi 11 janvier 2012 à 11:52 +0100, Borzenkov, Andrey a écrit : > Colleagues responsible for Oracle are reconfiguring it now. > OK. Since your hardware supports 1GB hugepages, you might try to use them as well. Not sure if your kernel is recent enough... cat /proc/cmdline ro root=LABEL=/ hugepagesz=1GB hugepages=512 > > If not, its normal to eat so much memory for page tables > > > > grep VmPTE /proc/*/status > > > > > > Forgive my ignorance. I thought that > > 1. PTE is 8 bytes per page, which is 4K which gives 2K per 1M of memory > 2. All processes sharing the same shared memory share the same page table It depends how oracle maps its SGA. It probably uses a method disallowing page table sharing. Anyway, hugetables for this kind of workload is a must.