Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 19 Nov 2002 19:57:15 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 19 Nov 2002 19:57:15 -0500 Received: from e6.ny.us.ibm.com ([32.97.182.106]:28125 "EHLO e6.ny.us.ibm.com") by vger.kernel.org with ESMTP id ; Tue, 19 Nov 2002 19:57:14 -0500 To: Andrew Morton cc: vasya vasyaev , "Nakajima, Jun" , linux-kernel@vger.kernel.org Reply-To: Gerrit Huizenga From: Gerrit Huizenga Subject: Re: Machine's high load when HIGHMEM is enabled In-reply-to: Your message of Tue, 19 Nov 2002 01:40:31 PST. <3DDA070F.CF2047BF@digeo.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <18339.1037754225.1@us.ibm.com> Date: Tue, 19 Nov 2002 17:03:45 -0800 Message-Id: Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2541 Lines: 72 Oracle usually likes its SGA locked in memory, so if it is set to request 800 MG of RAM on a 1 GB machine, I think you have tuned Oracle to be requesting too much SGA for your hardware. gerrit In message <3DDA070F.CF2047BF@digeo.com>, > : Andrew Morton writes: > vasya vasyaev wrote: > > > > Hi again, > > > > Let me try to explain what is this all about... > > > > Box has 1 GB of RAM, it's running oracle database. > > After some disk activity disk cache has 400 Mb, so 600 > > Mb is free > > And the other 400 megabytes will be freed up on demand. > > > Oracle is tuned for using of 800 Mb of RAM for SGA (as > > shared memory segment), so Oracle needs 800 Mb of RAM > > to be free before it's start, right ? > > No... If that were so, you'd never be able to start any > applications. > > > So when oracle starts it can't allocate this 800 Mb > > for SGA and fails to start... > > Well, maybe Oracle is failing to start. But maybe that's > not for the reasons you are assuming. > > > Where is a problem - in kernel which can't reduce disk > > cache to allow allocating of shared memory segment or > > in oracle ? > > If Oracle requests 800 megabytes from the kernel, it will get it. > It won't be able to mlock it (I'm guessing here). > > > BTW, free doesn't show that shared memory is in use > > when oracle is started and requested shared memory > > segment is allocated (and ipcs shows it). > > Yup, the "shared" accounting is always zero. Maybe we should > fix that, or remove it. > > > We need to control disk cache to reduce it as much as > > possible because it's not needed for oracle, much > > better is to allow oracle to control the RAM > > for it's use. > > > > As to compare, on solaris we mount ufs with > > "forcedirectio" mount option, which tells not to use > > disk cache. > > Please ensure that the failure is not some Oracle-specific setup > thing, and then provide specific details on the problem which you > are observing. The assumptions which you are making may not be > correct. > > Thanks. > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/