[Toybox] New toy: vmstat

[Elie De Brauwer]

Hello all,

In attachment you can find a no-nonsense vmstat implementation. Meaning 
most of the special things (which I personally never bothered to use) 
are dropped. (vmstat -d however is still under consideration, please 
shout if you're waiting for a vmstat -d or any other options).

The information is gathered from procfs and assumes linux >2.6.x.  One 
last comment is vmstat's dreaded first line where it tries to average 
the counters (where possible) is imho just broken.

Observe the snippet below:
edb at lapedb:~/today$ cat /proc/stat | grep ctxt ; cat /proc/uptime ; vmstat
ctxt 3021508
2317.09 17079.93
procs -----------memory---------- ---swap-- -----io---- -system-- 
----cpu----
  r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy 
id wa
  0  0      0 5773748  71032 1915324    0    0   100    83  126  163  6 
  1 92  1

Here I would expect the summary line to display the number of context 
switchs per second which is 3021508/2317 = 1304. However vmstat states 
this as 163. Now let's do some magic 163*8 = 1304. (Where 8 is the 
number of cpu's my laptop shows). Hence the result they give is number 
per second per core. While consecutive runs show the total value per 
second. So I ended up implementing the first line as something which is 
(in imho) what is was supposed to be. I will throw this odd behavior of 
vmstat back upstream.

my 2 cents, feedback welcome.
gr
E.

-- 
Elie De Brauwer

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