From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Theurer Subject: Re: [PATCH] Optimizing x86-64 xenlinux using global pagesfor user mode (take 2) Date: Wed, 30 Aug 2006 10:26:32 -0500 Message-ID: <44F5AE28.20902@us.ibm.com> References: <8FFF7E42E93CC646B632AB40643802A8D3A302@scsmsx412.amr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <8FFF7E42E93CC646B632AB40643802A8D3A302@scsmsx412.amr.corp.intel.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: "Nakajima, Jun" Cc: Ian Pratt , xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org Nakajima, Jun wrote: > Andrew Theurer wrote: > >> Ian Pratt wrote: >> >>>> The previous patch had a problem with the builder, which constructs >>>> the initial page tables with the USER bit on. And Xen couldn't >>>> distinguish kernel or use pages. It was partially checked avoiding >>>> the bug, and it's finished with this patch. >>>> >>> Thanks. Have you any updated benchmark numbers as the bug could have >>> been giving quite a performance boost before. >>> > > Looks like part of the boost was realized by the bug, but I still see > consistent and visible improvements with lmbench. If I turn on the > global bits for the kernel pages as well, I see more improvements, which > are comparable with or better than before. I think we need to do macro > benchmarks to see how this helps. > > >> FWIW, I had been running more extensive testing on changeset 11225 >> (before global-bit) and 11229 (global-bit with revert/fix for dom0 >> builder), and they do not match the initial testing I did with rev >> 11118 + global_1 patch. In fact, I am not seeing really any >> improvement. I am not sure what is wrong. Should I just test >> xen-unstable-tip+newest_patch and see where we stand? >> >> > > Yes, please. You shouldn't have observed any performance difference > between 11225 and 11229 because the changeset 11226 did not enable the > global bit. OK, then that would explain it :) I'll run tip+ your latest patch. -Andrew Theurer