From owner-freebsd-arm@freebsd.org Thu Jun 14 21:10:24 2018 Return-Path: Delivered-To: freebsd-arm@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id A2CED100723C for ; Thu, 14 Jun 2018 21:10:24 +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 C1B9482821 for ; Thu, 14 Jun 2018 21:10:23 +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 w5ELALDw046841; Thu, 14 Jun 2018 14:10:21 -0700 (PDT) (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 w5ELAL0N046840; Thu, 14 Jun 2018 14:10:21 -0700 (PDT) (envelope-from freebsd-rwg) From: "Rodney W. Grimes" Message-Id: <201806142110.w5ELAL0N046840@pdx.rh.CN85.dnsmgr.net> Subject: Re: GPT vs MBR for swap devices In-Reply-To: <20180614175622.GC35161@www.zefox.net> To: bob prohaska Date: Thu, 14 Jun 2018 14:10:21 -0700 (PDT) CC: Tom Vijlbrief , "freebsd-arm@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-arm@freebsd.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: "Porting FreeBSD to ARM processors." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 14 Jun 2018 21:10:24 -0000 > On Thu, Jun 14, 2018 at 09:53:57AM -0700, Rodney W. Grimes wrote: > > > > I would be very interested in seeing if resizing the swap partition > > in the example that greatly exceeds what the system expects as a > > max total swap helps to bring the OOM issue under control. > > > The swap partitions at my immediate disposal are > 1 GB USB flash > 1 GB microSD flash > 2 GB microSD flash > 3 GB USB mechanical > > What combination is apt to be most informative? My original intent > was to use 1 GB USB flash plus 1 GB microSD flash in hopes of a speed > gain from interleaving, but maybe that's no longer realistic. Anything > over 3 GB total causes the "too much swap" warning and I've never observed > more than about 1.2 GB of swap in use. Well if you do a swapon to the 3 GB USB Mechanical that should be all that is usable, so we could infact test the theory by doing that one first and adding anything to it and find out if it started to use the others. Or someone that knows the current code could tell us :-) It might be interesting to do in order the swapon commands to 1G USB flash, 1G SD flash, 2G SD flash, that should if what I think happens yeild a pretty even 1G of each usable, with 1G wasted on the 2G SD flash. > > I think the state of things is such that if you use up the > > max usable swap space on the first swap device, only that > > swap device well ever be used. I do not believe there is > > any attempts what so ever to split the allocation up so > > that you use the first fraction of each device. > > > > Swap usage seem to be spread among active partitions, though > how they're weighted is unclear to me. In days of yore there > was a little note about "interleaved" in swapinfo reports, but > I don't recall seeing that for a loong time. Maybe that feature > has gone away..... > > Thanks for reading, > > bob prohaska > > > > -- Rod Grimes rgrimes@freebsd.org