From owner-freebsd-virtualization@freebsd.org Sat Dec 2 04:02:34 2017 Return-Path: Delivered-To: freebsd-virtualization@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 7F075DF1992 for ; Sat, 2 Dec 2017 04:02:34 +0000 (UTC) (envelope-from freebsd-rwg@pdx.rh.CN85.dnsmgr.net) Received: from pdx.rh.CN85.dnsmgr.net (br1.CN84in.dnsmgr.net [69.59.192.140]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 643F77FCCB for ; Sat, 2 Dec 2017 04:02:33 +0000 (UTC) (envelope-from freebsd-rwg@pdx.rh.CN85.dnsmgr.net) Received: from pdx.rh.CN85.dnsmgr.net (localhost [127.0.0.1]) by pdx.rh.CN85.dnsmgr.net (8.13.3/8.13.3) with ESMTP id vB242G4e032506; Fri, 1 Dec 2017 20:02:16 -0800 (PST) (envelope-from freebsd-rwg@pdx.rh.CN85.dnsmgr.net) Received: (from freebsd-rwg@localhost) by pdx.rh.CN85.dnsmgr.net (8.13.3/8.13.3/Submit) id vB242DaJ032505; Fri, 1 Dec 2017 20:02:13 -0800 (PST) (envelope-from freebsd-rwg) From: "Rodney W. Grimes" Message-Id: <201712020402.vB242DaJ032505@pdx.rh.CN85.dnsmgr.net> Subject: Re: bhyve uses all available memory during IO-intensive operations In-Reply-To: <5bb5649f-5785-7baf-6871-625d1f63bd8b@ShaneWare.Biz> To: Shane Ambler Date: Fri, 1 Dec 2017 20:02:13 -0800 (PST) CC: Dustin Wenz , freebsd-virtualization@freebsd.org X-Mailer: ELM [version 2.4ME+ PL121h (25)] MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII X-BeenThere: freebsd-virtualization@freebsd.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: "Discussion of various virtualization techniques FreeBSD supports." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 02 Dec 2017 04:02:34 -0000 > On 02/12/2017 08:11, Dustin Wenz wrote: > > > > The commit history shows that chyves defaults to -S if you are > > hosting from FreeBSD 10.3 or later. I'm sure they had a reason for > > doing that, but I don't know what that would be. It seems to an > > inefficient use of main memory if you need to run a lot of VMs. > > It sounds like a reasonable solution to a problem. If host memory is > full it swaps some out, so a bhyve might have free mem but some could be > swapped out by the host. If the bhyve is out of mem, it's system swaps > to it's disk, so the host swaps it back in so that the bhyve can then > swap it to its disk... > > Wiring bhyve ram might be a reasonable solution as long as the hosts > physical ram isn't over allocated by bhyve guests. > > The best solution would involve a host and guest talking to each other > about used mem, but that would break the whole virtual machine illusion. > At the least it would involve a system telling the hardware what memory > is used and what is not, which just isn't something any system does. > Maybe that is an idea for the vm guest aware systems of the future. Its actually old technology, its called the memory balloon driver, but bhyve does not have that functionality, yet. -- Rod Grimes rgrimes@freebsd.org