[Toybox] ps and top (and Android)

[enh]

On Fri, Apr 29, 2016 at 5:45 PM, Rob Landley <rob at landley.net> wrote:
> On 04/29/2016 04:06 PM, enh wrote:
>> sorry, hadn't had time to look until now. notes:
>>
>> * the tid column seems very wrong. in particular, i see a lot of
>> duplicate tids. ah, the pid/tid columns don't auto-expand and are
>> truncating...
>>
>> GNU: 147139 130820 ?        00:00:00 default_ThreadM
>> toybox: 14713 13082 ?        00:00:00 default_ThreadM
>
> Hmmm, this sounds like a problem for PIDs too.

(yeah, sorry --- you can see that in my example above but i forgot to
actually call it out.)

> Let's see...
>
> $ ps -o pid:3,user:3,cmd:3
> PID USER CMD
> 18748 la+ bash
> 19147 la+ ps -o pid:3,user:3,cmd:3
>
> Ok,  I need to mark some columns as "expand this regardless" and others
> to indicate when they get truncated, and yet it truncates the cmdline at
> the right edge of the screen without indicating truncation...
>
> Hmmm... It's not quite obvious to me what the correct behavior is.
> (Numeric fields expand, command lines are silently truncated,
> non-command string fields do the + thing...? Maybe?)
>
>> * your -T is (like the desktop) showing the process name for each
>> thread. Android shows the thread name, which is probably what you want
>> if you're asking to see the threads in the first place.
>
> There's a thread name? Ah, the stat[2] field gets rewritten.

in the pthread implementation we read/write /proc/self/task/%d/comm.
toolbox's ps shows the text between ()s in the stat file. since you
have to read that anyway, that probably makes sense.

> How about if I treat PID != TID the same as kernel threads? [stat2name]
> in square brackets?

i reserve the right to come back later with strong negative feedback
from users, but that sounds good to me. it might actually be useful to
have a visible "not the main thread" distinction that doesn't require
skipping back to the pid/tid columns.

>> * you say 0 for BIT when you don't know, rather than leaving it blank
>> (like Android) or using '-' (like some other ps fields). i don't think
>> this matters, but i've attached a patch anyway.
>
> Applied.
>
>> * there's a whitespace mixup in the help text for -O. patch attached.
>
> Applied.
>
>> * i need to send you the Android-specific cruft for scheduling policy.
>
> Woot.

you say that because you haven't seen it yet :-)

attached. i kept the #ifs in lib/portability.* because there was no
obvious way to just say "this field isn't useful outside of Android".

>> other than that, i went through my old notes and i think everything
>> else is now done. i'll get AOSP synced this afternoon (must be friday
>> again!) and send you a patch for the scheduling policy names.
>
> I'll try to figure out what to do about column expansion. (Mental note:
> how does this impact top not wrapping lines and thus scrolling the
> screen...)
>
> Rob



-- 
Elliott Hughes - http://who/enh - http://jessies.org/~enh/
Android native code/tools questions? Mail me/drop by/add me as a reviewer.
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