From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with SMTP id 1808E60021B for ; Mon, 28 Dec 2009 15:51:26 -0500 (EST) Date: Mon, 28 Dec 2009 21:51:03 +0100 From: Pavel Machek Subject: Re: Tmem [PATCH 0/5] (Take 3): Transcendent memory Message-ID: <20091228205102.GC1637@ucw.cz> References: <20091225191848.GB8438@elf.ucw.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org To: Dan Magenheimer Cc: Nitin Gupta , Nick Piggin , Andrew Morton , jeremy@goop.org, xen-devel@lists.xensource.com, tmem-devel@oss.oracle.com, Rusty Russell , Rik van Riel , dave.mccracken@oracle.com, sunil.mushran@oracle.com, Avi Kivity , Schwidefsky , Balbir Singh , Marcelo Tosatti , Alan Cox , chris.mason@oracle.com, linux-mm , linux-kernel List-ID: Hi! > > achive this using > > > > some existing infrastructure in kernel. > > > > > > Hi Nitin -- > > > > > > Sorry if I sounded overly negative... too busy around the holidays. > > > > > > I'm definitely OK with exploring alternatives. I just think that > > > existing kernel mechanisms are very firmly rooted in the notion > > > that either the kernel owns the memory/cache or an asynchronous > > > device owns it. Tmem falls somewhere in between and is very > > > > Well... compcache seems to be very similar to preswap: in preswap case > > you don't know if hypervisor will have space, in ramzswap you don't > > know if data are compressible. > > Hi Pavel -- > > Yes there are definitely similarities too. In fact, I started > prototyping preswap (now called frontswap) with Nitin's > compcache code. IIRC I ran into some problems with compcache's > difficulties in dealing with failed "puts" due to dynamic > changes in size of hypervisor-available-memory. > > Nitin may have addressed this in later versions of ramzswap. That would be cool to find out. > One feature of frontswap which is different than ramzswap is > that frontswap acts as a "fronting store" for all configured > swap devices, including SAN/NAS swap devices. It doesn't > need to be separately configured as a "highest priority" swap > device. In many installations and depending on how ramzswap Ok, I'd call it a bug, not a feature :-). Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- 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