From owner-freebsd-arm@freebsd.org Fri Jan 8 14:14:14 2016 Return-Path: Delivered-To: freebsd-arm@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 600F9A67A5F for ; Fri, 8 Jan 2016 14:14:14 +0000 (UTC) (envelope-from paul@gromit.dlib.vt.edu) Received: from gromit.dlib.vt.edu (gromit.dlib.vt.edu [128.173.126.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "gromit.dlib.vt.edu", Issuer "Chumby Certificate Authority" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 3A6C4178F; Fri, 8 Jan 2016 14:14:14 +0000 (UTC) (envelope-from paul@gromit.dlib.vt.edu) Received: from gromit.chumby.lan (c-71-63-91-41.hsd1.va.comcast.net [71.63.91.41]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by gromit.dlib.vt.edu (Postfix) with ESMTPSA id BB6AE260; Fri, 8 Jan 2016 09:07:04 -0500 (EST) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 9.2 \(3112\)) Subject: Re: FYI: various 11.0-CURRENT -r293227 (and older) hangs on arm (rpi2): a description of sorts From: Paul Mather In-Reply-To: <5D7C239F-6D43-4C7A-B7F2-88E7488418B2@dsl-only.net> Date: Fri, 8 Jan 2016 09:07:05 -0500 Cc: Hans Petter Selasky , Ian Lepore , Warner Losh , freebsd-arm Content-Transfer-Encoding: quoted-printable Message-Id: <4F6FE513-088A-4B0F-9838-85A896758C13@gromit.dlib.vt.edu> References: <1452183170.1215.4.camel@freebsd.org> <1452196099.1215.12.camel@freebsd.org> <568EC4D8.7010106@selasky.org> <8B728C93-9C90-4821-A607-5D157F028812@dsl-only.net> <568ED810.8010309@selasky.org> <568ED92C.9070602@selasky.org> <97E0840E-987C-4893-9E63-EA51741CFC75@dsl-only.net> <5D7C239F-6D43-4C7A-B7F2-88E7488418B2@dsl-only.net> To: Mark Millard X-Mailer: Apple Mail (2.3112) X-BeenThere: freebsd-arm@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: "Porting FreeBSD to ARM processors." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 08 Jan 2016 14:14:14 -0000 On Jan 8, 2016, at 12:49 AM, Mark Millard wrote: > Top post of a major conclusion: >=20 > I have isolated a working vs. failing context for the hangs issue: > (Note that everything for world and ports and such is on the SSD root = partition in my examples.) >=20 > A) Using a swap file on the root partition as the swap space leads to = hangs when the space gets sufficient activity >=20 > vs. >=20 > B) Using a swap partition as the swap space works without hangs >=20 > It is the same SSD as before both ways. (I had to dump, repartition, = restore since I'd not provided space for a swap partition earlier.) >=20 > A swap partition on the sdcard as the swap space also works. >=20 >=20 > So it appears there is a problem with using swapfiles --at least when = they are on otherwise sometimes-also-busy file systems but possibly more = generally. (As the SSD has a USB SSD interface to the RPI2, swapfiles do = not provide trim support any more than swap partitions would.) >=20 > The SSD is likely noticeably faster in various respects and so may be = more of a challenge for swapfile handling in some way (via extra = file-system/IO/resource load with less time between various activities), = at least on rpi2's. This meshes with recent experience I have been having with CURRENT on a = BeagleBone Black. I use a swapfile on the SD card (which also hosts all = the OS file systems) and the system would regularly lock up, with GEOM = complaining on the console about I/O errors to the mmcsd0 device. In the past, too, I have experienced panics (on all my arm systems) when = the system attempts to page in from swap. For now, on the BeagleBone Black, I have attached an external USB hard = drive and am using a swap partition on there to see if it "solves" the = swap problem. The good news is that it hasn't locked up so far. = (Usually, the nightly periodic jobs are enough to provoke the problem.) It's good to hear, though, that a swap partition on the SD card also = works in your testing. I will try that next. Cheers, Paul.