From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Theurer Subject: Re: Why is 'emulate' as good as writable PT's? Date: Tue, 06 Jun 2006 17:02:02 -0500 Message-ID: <4485FB5A.6020903@us.ibm.com> References: <4485E557.2020005@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Keir Fraser Cc: Ian Pratt , Xen development list , Rolf Neugebauer List-Id: xen-devel@lists.xenproject.org Keir Fraser wrote: > > On 6 Jun 2006, at 21:28, Andrew Theurer wrote: > >> Yes, we definitely have a problem here. Tons of flushes with >> modified=1, and lots with <=10. The three benchmarks all seem to hit >> the same areas. Here is the output from running SDET, with snippets >> from System.map mixed in: > > Is this PAE? SMP guest? > > Do you know much about the SDET benchmark? For example, do you know > how big the mprotect() calls it makes are likely to be? If vma's are > small and fairly sparse then the writable pagetable batching won't be > a win. 1-way SMP kernel, PAE. not sure about the mprotect() calls. SDET basically calls a lot of utilities like ps, gcc, ispell, etc. Is it feasible to "xen-ify" unmap_vmas() and copy_page_range(), such that we use explicit hypercalls instead of faulting on the writes? -Andrew