Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats

[Shailabh Nagar]

Andrew Morton wrote:

> On Fri, 23 Jun 2006 13:14:41 -0400
> Shailabh Nagar <nagar@xxxxxxxxxxxxxx> wrote:
>
>  
>
> > The results show that differential between tgid on and off
> > starts becoming significant once the exit rate crosses roughly 1000
> > threads/second. Below that exit rate, the difference is negligible.
> > Above it, the difference starts climbing rapidly.
> >
> > So I guess the question is whether this rate of exit is representative
> > enough of real life to warrant making any more changes to the existing
> > patchset, beyond the locking changes in 2. above.
> >
> > > From my limited experience, I think this is too high an exit rate
> > to be worrying about overhead.
> >
> >    
>
> 1000/sec isn't terribly high.  CGI servers, shell scripts.
>
> And kernel development ;) A `pushpatch 1500' here does 992 fork/exec/exit
> per second.
>  
Don't all of these create new tasks, not threads ?

Single-threaded tasks fork/exec/exit'ing is not a problem since per-tgid 
data is not sent in that
case (since it will be identical to the per-tid data).

> >        %ovhd of tgid on over off
> >        (higher is worse)
> >
> > Exit     User     Sys     Elapsed
> > Rate     Time     Time    Time
> >
> > 2283      25.76  649.41   -0.14
> > 1193     -10.53   88.81   -0.12
> > 963      -11.90    3.28   -0.10
> > 806       -8.54   -0.84    0.16
> > 694       -4.41    2.38    0.03
> >    
>
> Oh wow.  Something's gone quadratic there.
>  

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