Date: Tue, 26 Jun 2018 23:30:52 -0700 From: Mark Millard <marklmi@yahoo.com> To: bob prohaska <fbsd@www.zefox.net> Cc: freebsd-arm@freebsd.org Subject: Re: RPI3 swap experiments, was Re: GPT vs MBR for swap devices Message-ID: <CC72E766-03CB-476C-8F2B-DAAC266CE63D@yahoo.com> In-Reply-To: <20180627054027.GA22144@www.zefox.net> 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> <20180627054027.GA22144@www.zefox.net>
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On 2018-Jun-26, at 10:40 PM, bob prohaska <fbsd at www.zefox.net> wrote: > On Tue, Jun 26, 2018 at 07:09:09PM -0700, Mark Millard wrote: >>=20 >>=20 >> On 2018-Jun-26, at 3:28 PM, bob prohaska <fbsd at www.zefox.net> = wrote: >>=20 >>> 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: >>>>=20 >>>>> On Tue, Jun 26, 2018 at 07:37:59AM -0700, Mark Millard wrote: >>>>>>=20 >>>>>>=20 >>>>>> . . . >>>>>>=20 >>>>>> 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. >>>>>>=20 >>>>> 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. >>>>>=20 >>>>=20 >>>> 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: >>>>=20 >>>> 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). >>>>=20 >>>> exists. So I was remembering incorrectly. >>>>=20 >>>> 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. >>>>=20 >>>=20 >>> I just didn't bother to record successful runs. I'm logging one now. >>>=20 >>>> 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. >>>>=20 >>> 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".=20 >=20 >=20 >>>=20 >>> Are there other combinations I've overlooked? The first two don't = seem=20 >>> worth repeating, at least not often. >>=20 >> "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 ). >>=20 >> 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. >>=20 >> 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.) >>=20 >> 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). >=20 > 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=20 > too familiar to be interesting.=20 "crashes and /dev/da0 errors": A) Any examples of /dev/da0 errors without crashes? B) Any examples of crashes without /dev/da0 errors? C) All examples that do either also does the other (so both always go together)? (I've having trouble parsing a specific meaning for the reference. I did not go back trough all the logs again to identify the combinations recorded.) For (A), have you tried any examples of: sufficient swap on mmcsd0 (or other such) with no swap on da0 (but /usr and /var on /dev/da0)? If yes, did you check on if there were /dev/da0 errors logged? What, if any, /dev/da0 errors where logged? None? For (B), have you tried any examples of: insufficient swap on (say) mmcsd0 and no use of the /dev/da0 drive that has reported errors at all, /usr/ and /var not on mmcsd0 (or whatever was used for swap) either? Did some drive end up reporting errors? Which? Did the system still crash as well? Have such test-context combinations been tried? Without any logs to look at for such alternatives, I can not try to compare/contrast such to the others examples. >>=20 >> 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. >>=20 > =46rom what I've seen, OOMA isn't associated with da0 errors and = crashes. > To see the latter, OOMA must be avoided. =3D=3D=3D Mark Millard marklmi at yahoo.com ( dsl-only.net went away in early 2018-Mar)
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