Date: Fri, 8 Jan 2016 09:07:05 -0500 From: Paul Mather <paul@gromit.dlib.vt.edu> To: Mark Millard <markmi@dsl-only.net> Cc: Hans Petter Selasky <hps@selasky.org>, Ian Lepore <ian@freebsd.org>, Warner Losh <imp@bsdimp.com>, freebsd-arm <freebsd-arm@freebsd.org> Subject: Re: FYI: various 11.0-CURRENT -r293227 (and older) hangs on arm (rpi2): a description of sorts Message-ID: <4F6FE513-088A-4B0F-9838-85A896758C13@gromit.dlib.vt.edu> In-Reply-To: <5D7C239F-6D43-4C7A-B7F2-88E7488418B2@dsl-only.net> References: <E0379BE9-308A-4219-A8AE-A5FFE828BA93@dsl-only.net> <1452183170.1215.4.camel@freebsd.org> <FB0D5486-AD27-44A7-86CA-68989AE08EC7@dsl-only.net> <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> <B7E8D0FD-B3A9-40DF-B0ED-9D3041F8B2A2@dsl-only.net> <D44C4EF3-0976-45E7-944A-A8F23D3D89BF@dsl-only.net> <CANCZdfqGUJ19Gbu=ermSGh1LJ5N9OPEyRYH9kPEAoaUmTuObdw@mail.gmail.com> <97E0840E-987C-4893-9E63-EA51741CFC75@dsl-only.net> <5D7C239F-6D43-4C7A-B7F2-88E7488418B2@dsl-only.net>
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On Jan 8, 2016, at 12:49 AM, Mark Millard <markmi@dsl-only.net> 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.
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