GPT vs MBR for swap devices
Mark Millard
marklmi at yahoo.com
Mon Jun 18 23:42:25 UTC 2018
On 2018-Jun-18, at 4:04 PM, bob prohaska <fbsd at www.zefox.net> wrote:
> On Sat, Jun 16, 2018 at 04:03:06PM -0700, Mark Millard wrote:
>>
>> Since the "multiple swap partitions across multiple
>> devices" context (my description) is what has problems,
>> it would be interesting to see swapinfo information
>> from around the time frame of the failures: how much is
>> used vs. available on each swap partition? Is only one
>> being (significantly) used? The small one (1 GiByte)?
>>
> There are some preliminary observations at
>
> http://www.zefox.net/~fbsd/rpi3/swaptests/newtests/1gbusbflash_1gbsdflash_swapinfo/1gbusbflash_1gbsdflash_swapinfo.log
>
> If you search for 09:44: (the time of the OOM kills) it looks like
> both swap partitions are equally used, but only 8% full.
>
> At this point I'm wondering if the gstat interval (presently 10 seconds)
> might well be shortened and the ten second sleep eliminated. On the runs
> that succeed swap usage changes little in twenty seconds, but the failures
> seem to to culminate rather briskly.
One thing I find interesting somewhat before the OOM activity is
the 12355 ms/w and 12318 ms/w on da0 and da0d that goes along
with having 46 or 33 L(q) and large %busy figures in the same
lines --and 0 w/s on every line:
Mon Jun 18 09:42:05 PDT 2018
Device 1K-blocks Used Avail Capacity
/dev/da0b 1048576 3412 1045164 0%
/dev/mmcsd0s3b 1048576 3508 1045068 0%
Total 2097152 6920 2090232 0%
dT: 10.043s w: 10.000s
L(q) ops/s r/s kBps ms/r w/s kBps ms/w d/s kBps ms/d %busy Name
0 0 0 0 0.0 0 9 10.8 0 0 0.0 0.1 mmcsd0
46 0 0 0 0.0 0 16 12355 0 0 0.0 85.9 da0
0 0 0 0 0.0 0 9 10.8 0 0 0.0 0.1 mmcsd0s3
0 0 0 0 0.0 0 9 10.8 0 0 0.0 0.1 mmcsd0s3a
33 0 0 0 0.0 0 22 12318 0 0 0.0 114.1 da0d
Mon Jun 18 09:42:25 PDT 2018
Device 1K-blocks Used Avail Capacity
/dev/da0b 1048576 3412 1045164 0%
/dev/mmcsd0s3b 1048576 3508 1045068 0%
Total 2097152 6920 2090232 0%
The kBps figures for the writes are not very big above.
There is an earlier example of something similar, again for
da0 and da0d having the large ms/w (and ms/r here):
Mon Jun 18 09:32:00 PDT 2018
Device 1K-blocks Used Avail Capacity
/dev/da0b 1048576 3516 1045060 0%
/dev/mmcsd0s3b 1048576 3604 1044972 0%
Total 2097152 7120 2090032 0%
dT: 10.010s w: 10.000s
L(q) ops/s r/s kBps ms/r w/s kBps ms/w d/s kBps ms/d %busy Name
0 1 0 0 0.0 1 8 5.4 0 0 0.0 0.2 mmcsd0
6 1 0 1 373.9 1 18 1070 0 0 0.0 73.6 da0
0 0 0 0 0.0 0 7 6.1 0 0 0.0 0.1 mmcsd0s2
0 0 0 0 0.0 0 7 6.1 0 0 0.0 0.1 ufs/rootfs
4 1 0 1 373.9 1 18 1243 0 0 0.0 73.6 da0d
Mon Jun 18 09:32:20 PDT 2018
Device 1K-blocks Used Avail Capacity
/dev/da0b 1048576 3516 1045060 0%
/dev/mmcsd0s3b 1048576 3604 1044972 0%
Total 2097152 7120 2090032 0%
===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)
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