From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail6.bemta12.messagelabs.com (mail6.bemta12.messagelabs.com [216.82.250.247]) by kanga.kvack.org (Postfix) with ESMTP id A99486B002D for ; Fri, 28 Oct 2011 14:43:43 -0400 (EDT) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <20138.62532.493295.522948@quad.stoffel.home> Date: Fri, 28 Oct 2011 14:28:20 -0400 From: "John Stoffel" Subject: RE: [GIT PULL] mm: frontswap (for 3.2 window) In-Reply-To: References: <75efb251-7a5e-4aca-91e2-f85627090363@default> <20111027215243.GA31644@infradead.org> <1319785956.3235.7.camel@lappy> <552d2067-474d-4aef-a9a4-89e5fd8ef84f@default> Sender: owner-linux-mm@kvack.org List-ID: To: Dan Magenheimer Cc: Johannes Weiner , Pekka Enberg , Cyclonus J , Sasha Levin , Christoph Hellwig , David Rientjes , Linus Torvalds , linux-mm@kvack.org, LKML , Andrew Morton , Konrad Wilk , Jeremy Fitzhardinge , Seth Jennings , ngupta@vflare.org, Chris Mason , JBeulich@novell.com, Dave Hansen , Jonathan Corbet >>>>> "Dan" == Dan Magenheimer writes: Dan> Second, have you read http://lwn.net/Articles/454795/ ? Dan> If not, please do. If yes, please explain what you don't Dan> see as convincing or tangible or documented. All of this Dan> exists today as working publicly available code... it's Dan> not marketing material. I was vaguely interested, so I went and read the LWN article, and it didn't really provide any useful information on *why* this is such a good idea. Particularly, I didn't see any before/after numbers which compared the kernel running various loads both with and without these transcendental memory patches applied. And of course I'd like to see numbers when they patches are applied, but there's no TM (Transcendental Memory) in actual use, so as to quantify the overhead. Your article would also be helped with a couple of diagrams showing how this really helps. Esp in the cases where the system just endlessly says "no" to all TM requests and the kernel or apps need to them fall back to the regular paths. In my case, $WORK is using linux with large memory to run EDA simulations, so if we swap, performance tanks and we're out of luck. So for my needs, I don't see how this helps. For my home system, I run an 8Gb RAM box with a couple of KVM VMs, NFS file service to two or three clients (not counting the VMs which mount home dirs from there as well) as well as some light WWW developement and service. How would TM benefit me? I don't use Xen, don't want to play with it honestly because I'm busy enough as it is, and I just don't see the hard benefits. So the onus falls on *you* and the other TM developers to sell this code and it's benefits (and to acknowledge it's costs) to the rest of the Kernel developers, esp those who hack on the VM. If you can't come up with hard numbers and good examples with good numbers, then you're out of luck. Thanks, John -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org