From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 8 Feb 2001 15:26:42 -0700 From: Cort Dougan To: David Edelsohn Cc: paulus@linuxcare.com.au, Dan Malek , Gabriel Paubert , tom_gall@vnet.ibm.com, linuxppc-commit@hq.fsmlabs.com, linuxppc-dev Subject: Re: context overflow Message-ID: <20010208152641.P24312@hq.fsmlabs.com> References: <200102082208.RAA22218@mal-ach.watson.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <200102082208.RAA22218@mal-ach.watson.ibm.com>; from David Edelsohn on Thu, Feb 08, 2001 at 05:08:32PM -0500 Sender: owner-linuxppc-dev@lists.linuxppc.org List-Id: } statements about which VMM design is best. You can create a wonderful } engineer solution, but are you solving the problem or simply masking a } symptom? Would you characterize AIX as an OS that takes advantage of the VMM design of the PowerPC? From the benchmarks I did it appeared to suffer the same problem that Linux/PPC did at that time. The problem being, a straightforward implementation of the software side of the VM design of the PowerPC. After some general improvements in the MM system of Linux/PPC we sped things up by a large amount by doing what you claim is a mistake. We widened the gap between Linux/PPC and what was probably the best example of what VM design can come from knowledge of the PPC architecture (in AIX). AIX can't claim to be doing it better. I was unable to look under the hood of AIX, of course, but my benchmarks did show that the _ONLY_ thing that mattered - wall clock time of user apps - was improved. Doing things that non-PPC way is not a flaw if it results in better performance. I do stand by our design, and the choices we made, but I'm open to suggestion for better ways to do it. I can certainly believe there's a lot of room for improvement. This is linux, though - actual working code speaks more loudly and clearly than anything else. Do you have an example of a better way of doing a VM system in Linux/PPC? We can't change the page table layout. That's something we're stuck with, in one form or another, in Linux no matter what (not our decision). What does Kitchewan do for a VM subsystem? Can you give me an overview of the design? ** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/