RPI3 swap experiments (r338342 with vm.pageout_oom_seq="1024")
Ronald Klop
ronald-lists at klop.ws
Sun Sep 2 17:57:02 UTC 2018
On Sun, 02 Sep 2018 17:27:17 +0200, bob prohaska <fbsd at www.zefox.net>
wrote:
> On Sun, Sep 02, 2018 at 06:57:15AM -0700, Mark Millard wrote:
>> Was this with or without (presuming a ufs file system):
>>
>> tunefs: trim: (-t) enabled
>>
>> ? If enabled, with or without:
>>
>> sysctl vfs.ffs.dotrimcons=1
>>
>> In other words: was "consolidation of TRIM / BIO_DELETE
>> commands to the UFS/FFS filesystem" enabled? Disabled?
>>
>
> No, it was not. By all accounts TRIM enabling won't affect USB2.0
> devices,
> and it's fairly clear the bottleneck is in USB, not microSD. Trim is
> enabled
> for mmcsd0s2a, but sysctl vfs.ffs.dotrimcons=1 hasn't been invoked. I'll
> turn
Sysctl vfs.ffs.dotrimcons is about FFS/UFS. Not about swap.
So unless there is UFS on the same device as swap, the sysctl will not
have any effect.
Regards,
Ronald.
> it on later, to check for bad side effects, but there's no obvious
> reason to
> think it'll help.
>
> At the moment the diskscript is reporting:
>
> dT: 10.005s 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 5.2 0 0
> 0.0 0.2 mmcsd0
> 10 0 0 0 0.0 0 2 13790 0 0
> 0.0 89.9 da0
> 0 0 0 0 0.0 0 2 3.9 0 0
> 0.0 0.1 mmcsd0s2b
> 0 0 0 0 0.0 0 9 5.2 0 0
> 0.0 0.2 mmcsd0s2
> 9 0 0 0 0.0 0 2 13790 0 0
> 0.0 89.9 da0b
> Sun Sep 2 08:17:14 PDT 2018
> Device 1K-blocks Used Avail Capacity
> /dev/da0b 1048576 494352 554224 47%
> /dev/mmcsd0s2b 1048576 478860 569716 46%
> Total 2097152 973212 1123940 46%
> Sep 2 08:14:38 www kernel: swap_pager: indefinite wait buffer: bufobj:
> 0, blkno: 1649558, size: 4096
> Sep 2 08:14:38 www kernel: swap_pager: indefinite wait buffer: bufobj:
> 0, blkno: 1654590, size: 16384
>
> Top is reporting ~10-50% idle time, not surprising given delays writing
> to da0b.
> I was hoping the pager might favor microSD given the much faster I/O
> times,
> but evidently not. Seems to be a strict round-robin division of labor.
>
> Thanks for reading!
>
> bob prohaska
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