From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sd0208e0.au.ibm.com (d23rh904.au.ibm.com [202.81.18.202]) by ausmtp04.au.ibm.com (8.13.8/8.13.8) with ESMTP id l224Z5vA304400 for ; Fri, 2 Mar 2007 15:35:05 +1100 Received: from d23av03.au.ibm.com (d23av03.au.ibm.com [9.190.250.244]) by sd0208e0.au.ibm.com (8.13.8/8.13.8/NCO v8.2) with ESMTP id l224MEne184240 for ; Fri, 2 Mar 2007 15:22:14 +1100 Received: from d23av03.au.ibm.com (loopback [127.0.0.1]) by d23av03.au.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id l224Igmm029715 for ; Fri, 2 Mar 2007 15:18:43 +1100 Message-ID: <45E7A59E.6020004@in.ibm.com> Date: Fri, 02 Mar 2007 09:48:38 +0530 From: Balbir Singh Reply-To: balbir@in.ibm.com MIME-Version: 1.0 Subject: Re: The performance and behaviour of the anti-fragmentation related patches References: <20070301101249.GA29351@skynet.ie> <20070301160915.6da876c5.akpm@linux-foundation.org> <45E7835A.8000908@in.ibm.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Linus Torvalds Cc: Andrew Morton , Mel Gorman , npiggin@suse.de, clameter@engr.sgi.com, mingo@elte.hu, jschopp@austin.ibm.com, arjan@infradead.org, mbligh@mbligh.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: Linus Torvalds wrote: > > On Fri, 2 Mar 2007, Balbir Singh wrote: >>> My personal opinion is that while I'm not a huge fan of virtualization, >>> these kinds of things really _can_ be handled more cleanly at that layer, >>> and not in the kernel at all. Afaik, it's what IBM already does, and has >>> been doing for a while. There's no shame in looking at what already works, >>> especially if it's simpler. >> Could you please clarify as to what "that layer" means - is it the >> firmware/hardware for virtualization? or does it refer to user space? > > Virtualization in general. We don't know what it is - in IBM machines it's > a hypervisor. With Xen and VMware, it's usually a hypervisor too. With > KVM, it's obviously a host Linux kernel/user-process combination. > Thanks for clarifying. > The point being that in the guests, hotunplug is almost useless (for > bigger ranges), and we're much better off just telling the virtualization > hosts on a per-page level whether we care about a page or not, than to > worry about fragmentation. > > And in hosts, we usually don't care EITHER, since it's usually done in a > hypervisor. > >> It would also be useful to have a resource controller like per-container >> RSS control (container refers to a task grouping) within the kernel or >> non-virtualized environments as well. > > .. but this has again no impact on anti-fragmentation. > Yes, I agree that anti-fragmentation and resource management are independent of each other. I must admit to being a bit selfish here, in that my main interest is in resource management and we would love to see a well written and easy to understand resource management infrastructure and controllers to control CPU and memory usage. Since the issue of per-container RSS control came up, I wanted to ensure that we do not mix up resource control and anti-fragmentation. -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL -- 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