From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 2 May 2006 13:24:09 +0200 From: Ingo Molnar Subject: Re: [patch 00/14] remap_file_pages protection support Message-ID: <20060502112409.GA28159@elte.hu> References: <20060430172953.409399000@zion.home.lan> <4456D5ED.2040202@yahoo.com.au> <4456D85E.6020403@yahoo.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4456D85E.6020403@yahoo.com.au> Sender: owner-linux-mm@kvack.org Return-Path: To: Nick Piggin Cc: blaisorblade@yahoo.it, Andrew Morton , linux-kernel@vger.kernel.org, Linux Memory Management List-ID: * Nick Piggin wrote: > >Let's try get back to the good old days when people actually reported > >their bugs (togther will *real* numbers) to the mailing lists. That way, > >everybody gets to think about and discuss the problem. > > Speaking of which, let's see some numbers for UML -- performance and > memory. I don't doubt your claims, but I (and others) would be > interested to see. firstly, thanks for the review feedback! originally i tested this feature with some minimal amount of RAM simulated by UML 128MB or so. That's just 32 thousand pages, but still the improvement was massive: context-switch times in UML were cut in half or more. Process-creation times improved 10-fold. With this feature included I accidentally (for the first time ever!) confused an UML shell prompt with a real shell prompt. (before that UML was so slow [even in "skas mode"] that you'd immediately notice it by the shell's behavior) the 'have 1 vma instead of 32,000 vmas' thing is a really, really big plus. It makes UML comparable to Xen, in rough terms of basic VM design. Now imagine a somewhat larger setup - 16 GB RAM UML instance with 4 million vmas per UML process ... Frankly, without sys_remap_file_pages_prot() the UML design is still somewhat of a toy. Ingo -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org