From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755167Ab1J0WVy (ORCPT ); Thu, 27 Oct 2011 18:21:54 -0400 Received: from acsinet15.oracle.com ([141.146.126.227]:53407 "EHLO acsinet15.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754569Ab1J0WVx convert rfc822-to-8bit (ORCPT ); Thu, 27 Oct 2011 18:21:53 -0400 MIME-Version: 1.0 Message-ID: Date: Thu, 27 Oct 2011 15:21:39 -0700 (PDT) From: Dan Magenheimer To: Christoph Hellwig Cc: David Rientjes , Linus Torvalds , linux-mm@kvack.org, LKML , Andrew Morton , Konrad Wilk , Jeremy Fitzhardinge , Seth Jennings , ngupta@vflare.org, levinsasha928@gmail.com, Chris Mason , JBeulich@novell.com, Dave Hansen , Jonathan Corbet , Neo Jia Subject: RE: [GIT PULL] mm: frontswap (for 3.2 window) References: <75efb251-7a5e-4aca-91e2-f85627090363@default 20111027215243.GA31644@infradead.org> In-Reply-To: <20111027215243.GA31644@infradead.org> X-Priority: 3 X-Mailer: Oracle Beehive Extensions for Outlook 2.0.1.4.1.0 (410211) [OL 12.0.6562.5003] Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8BIT X-Source-IP: ucsinet22.oracle.com [156.151.31.94] X-CT-RefId: str=0001.0A020205.4EA9D976.00AE,ss=1,re=0.000,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > From: Christoph Hellwig [mailto:hch@infradead.org] > Subject: Re: [GIT PULL] mm: frontswap (for 3.2 window) > > On Thu, Oct 27, 2011 at 02:49:31PM -0700, Dan Magenheimer wrote: > > If Linux truly subscribes to the "code rules" mantra, no core > > VM developer has proposed anything -- even a design, let alone > > working code -- that comes close to providing the functionality > > and flexibility that frontswap (and cleancache) provides, and > > frontswap provides it with a very VERY small impact on existing > > kernel code AND has been posted and working for 2+ years. > > (And during that 2+ years, excellent feedback has improved the > > "kernel-ness" of the code, but NONE of the core frontswap > > design/hooks have changed... because frontswap _just works_!) > > It might work for whatever defintion of work, but you certainly couldn't > convince anyone that matters that it's actually sexy and we'd actually > need it. Only actually working on Xen of course doesn't help. > > In the end it's a bunch of really ugly hooks over core code, without > a clear defintion of how they work or a killer use case. Hi Christoph -- You might find it useful to read the whole base email and/or the lwn article referenced. Frontswap and cleancache have now gone far beyond X-e-n** and even beyond virtualization. That's why my talk at Linuxcon was titled "Transcendent Memory: Not Just for Virtualization Anymore". (And I stated at that talk that I have personally not written a line of X-e-n code in over a year now.) The same frontswap hooks _just work_ for zcache, RAMster and (soon) KVM too... and there's more uses coming. Those that take the time to understand its use model DO find frontswap useful. Is "sexy" or "killer use case" a requirement for Linus to merge code now? If so, he can plan to spend a lot more time diving as I'll bet there isn't much code that measures up. Thanks, Dan ** /me suspects that Christoph has a /dev/null filter for email containing that word so has cleverly spelled it out to defeat that filter :-)