Lethargic rpi3, but seemingly still running

[bob prohaska]

On Tue, Jul 23, 2019 at 05:19:27AM +0100, Jamie Landeg-Jones wrote:
> bob prohaska <fbsd at www.zefox.net> wrote:
> 
> > Here's a snippet of systat -v 1 output while un-tarring firefox files. 
> > %busy was close to zero, it looks like there's congestion or a deadlock
> > writing to the microSD card. At the time things like cd and ls were
> > very slow to respond (tens of seconds)
> >
> >                                                        28 pdpgs       cpu2:ast
> > Disks mmcsd   da0 pass0                                   intrn       cpu3:ast
> > KB/t  12.00  0.00  0.00                            152904 wire      9 cpu0:preem
> > tps       5     0     0                             80072 act      51 cpu1:preem
> > MB/s   0.06  0.00  0.00                            671344 inact    80 cpu2:preem
> > %busy   213     0     0                               120   21104  27 cpu3:preem
> 
> You say "close to zero", but it's 213(!) in the output you gave!
>
 
Sorry, I was referring the %idle number above the bargraph and inverting the 
fraction, without noticing the %busy in the Disks output.

At the moment the same machine is compiling clang8 with about 900M of swap in use,
here is another sample:
Disks mmcsd   da0 pass0                               264 intrn       cpu3:ast
KB/t   5.51  5.77  0.00                            169680 wire    641 cpu0:pree
tps     461   457     0                            645096 act    1612 cpu1:pree
MB/s   2.48  2.58  0.00                              2280 inact  1522 cpu2:pree
%busy    77    50     0 

Swap is on both mmcsd and da0 (Samsung Evo+ microsd and a Sandisk usb3 flash drive). 

> However, I suspected something like that - high %busy whilst little actual
> transfers taking place. I've seen it before, along with the characteristics
> you describe, but unfortunately I don't have a fix.
> 

So far I think the problem has only been obvious when bsdtar is running. If
there's another way to provoke it that might be interesting to try.

Thanks for reading more closely than I wrote!

bob prohaska