# top -m io missing documentation?



## tobiam (Mar 2, 2017)

Hello,

can it be that `top -m io` is missing documentation? I can' find out what the values


```
VCSW  IVCSW   READ  WRITE  FAULT  TOTAL PERCENT
```

actually mean. I can imagine the meaning of Read, Write, Total and Percent looking at them, but while in the CPU mode things seem documented, I don't see documentation for these. Also I could not find out how to order by writes for example.


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## tobiam (Mar 2, 2017)

Okay, so according to the source I'd say VCSW are IVCSW are voluntary context switches and involuntary context switches, which I find interesting, cause they seem to be CPU related, despite being in the IO mode of top?

And if I get this right the others refer to ru_inblock and ru_outblock from getrusage(2) is supposed to "number of times the file system had to perform input/output" and fault appears to be "the number of page faults serviced that required I/O activity"

EDIT: Oh the context switches might make sense, cause it might wait for IO.

Also strangely enough ordering seems to work as expected now.

I still think it would be nice to have it in the man page, or otherwise have getrusage(2) as a reference in the "SEE ALSO" section.


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## tobik@ (Mar 3, 2017)

tobiam said:


> I still think it would be nice to have it in the man page, or otherwise have getrusage(2) as a reference in the "SEE ALSO" section.


Indeed. Now that you have done the research already, submit a patch maybe? 

P.S.: There are open bugs for this already (PR 199637, PR 142917), but they seem to have gone nowhere. Judging by https://lists.freebsd.org/pipermail/freebsd-questions/2007-September/158479.html this has been known for quite a long time...


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## grahamperrin@ (Sep 12, 2021)

tobik@ said:


> … (PR 199637, PR 142917), but they seem to have gone nowhere. …



Both bugs are now _Closed FIXED_. 

<https://www.freebsd.org/cgi/man.cgi?query=top&sektion=1&manpath=FreeBSD+13.0-RELEASE#SEE_ALSO> under *top(1)* includes a reference to getrusage(2) with interpretations.


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