Date: Tue, 26 Jun 2018 19:09:09 -0700 From: Mark Millard <marklmi@yahoo.com> To: bob prohaska <fbsd@www.zefox.net> Cc: Jamie Landeg-Jones <jamie@catflap.org>, Warner Losh <imp@bsdimp.com>, freebsd-arm <freebsd-arm@freebsd.org> Subject: Re: RPI3 swap experiments, was Re: GPT vs MBR for swap devices Message-ID: <28012DFB-37A0-461A-BB62-CD3EE61E82F0@yahoo.com> In-Reply-To: <20180626222834.GA20270@www.zefox.net> References: <20180623143218.GA6905@www.zefox.net> <03C2D3C4-6E90-4054-AF79-BD7FE2B7958D@yahoo.com> <20180624231020.GA11132@www.zefox.net> <C87C40CF-15B2-4137-892C-F2ADBAB32418@yahoo.com> <20180626052451.GA17293@www.zefox.net> <CANCZdfpXyzxzOZ8pqcRtuFsxYx5Jjs9oSL1ok2sGVPHdiB0qVQ@mail.gmail.com> <201806261040.w5QAeBKq035183@donotpassgo.dyslexicfish.net> <A6986B21-FF6E-48F5-9F3A-06B3D2A92C55@yahoo.com> <20180626151843.GD17293@www.zefox.net> <3525D7C7-F848-45A1-BD85-2DAC895DF48C@yahoo.com> <20180626222834.GA20270@www.zefox.net>
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On 2018-Jun-26, at 3:28 PM, bob prohaska <fbsd at www.zefox.net> wrote: > On Tue, Jun 26, 2018 at 01:15:54PM -0700, Mark Millard wrote: >> On 2018-Jun-26, at 8:18 AM, bob prohaska <fbsd at www.zefox.net> wrote: >> >>> On Tue, Jun 26, 2018 at 07:37:59AM -0700, Mark Millard wrote: >>>> >>>> >>>> . . . >>>> >>>> As I remember, Bob P. Did reproduce drive errors even without >>>> the problem drive being used for swapping. This too suggests >>>> (A) as separate activity. >>>> >>> Indeed, it is a requirement. If the suspect device is used for swapping >>> OOMA kills prevent the test from progressing to the point of failure. >>> >> >> Looking back at http://www.zefox.net/~fbsd/rpi3/swaptests/ >> and information about /dev/da0 rive errors it does not >> appear that a combination with: >> >> A) sufficient swap (> 1.5 GiByte total?) but no use of swap on >> any partition on /dev/da0 >> and: >> B) use of /dev/da0 for /usr/ and /var/ >> and: >> C) Records from the console showing errors (or notes >> indicating lack of such errors). >> >> exists. So I was remembering incorrectly. >> >> I'm not claiming such a combination is the best direction for >> the next tests, but absent such tests there is no >> compare/contrast to know if /dev/da0 would still get errors >> despite the system having sufficient swap present on other >> drives. Thus, I would not go so far as "is a requirement" on >> the evidence available. >> > > I just didn't bother to record successful runs. I'm logging one now. > >> We do have evidence for the system having insufficient swap >> space: this context seems to have the current status "is >> sufficient but might not be necessary" for /dev/da0 >> getting drive errors. >> > Not sure I understand here. Basically there seem to be three cases: > Enough swap not on da0, -j4 buildworld completes. > Any swap on da0, -j4 buildworld is killed by OOMA > Not enough swap not on da0, -j4 buildworld crashes the machine eventually. > > Are there other combinations I've overlooked? The first two don't seem > worth repeating, at least not often. "buildworld completes with /dev/da0 errors" vs. "buildworld completes without /dev/da0 errors" (for: enough swap not on /dev/da0 with no swap on /dev/da0 ). That is a little simplistic, as there can be multiple retries before FreeBSD gives up. Normal is no retries needed. Going from rare single retries to frequent multiple retries but no giving-up to it giving up sometimes is all abnormal as I understand. But there are degrees of abnormal. And, yes, I have had past examples of significant drive reports during buildworld that let buildworld appear to complete. (Not that I trusted the result or the drive involved after such, at least as the drive was powered/connected at the time.) For "any swap on da0" and "not enough swap not on da0" (with no swap on da0) I'd add to your descriptions: "with /dev/da0 errors" (again simplistic). This goes along with my suggestion to split the /dev/da0 error investigation from the investigations of OMMA behavior and crashing-the-machine: avoiding any confounding. (For now I do not have access to a context for doing rpi3 examples myself.) === Mark Millard marklmi at yahoo.com ( dsl-only.net went away in early 2018-Mar)
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