Date: Tue, 26 Jun 2018 22:40:27 -0700 From: bob prohaska <fbsd@www.zefox.net> To: Mark Millard <marklmi@yahoo.com> Cc: freebsd-arm@freebsd.org, bob prohaska <fbsd@www.zefox.net> Subject: Re: RPI3 swap experiments, was Re: GPT vs MBR for swap devices Message-ID: <20180627054027.GA22144@www.zefox.net> In-Reply-To: <28012DFB-37A0-461A-BB62-CD3EE61E82F0@yahoo.com> References: <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> <28012DFB-37A0-461A-BB62-CD3EE61E82F0@yahoo.com>
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On Tue, Jun 26, 2018 at 07:09:09PM -0700, Mark Millard wrote: > > > 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. ^^^^^^^^^^ OK, here's my error. The third case should have been "not enough swap on mmcsd0". > > > > 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). The only case where I've seen crashes and /dev/da0 errors is with insufficient swap on mmcsd0. I've come to ignore OOMA kills as too familiar to be interesting. > > 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. > >From what I've seen, OOMA isn't associated with da0 errors and crashes. To see the latter, OOMA must be avoided. Thanks for reading, bob prohaska
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