Re: RLIMIT_RTTIME documentation for getrlimit.2

[Peter Zijlstra]

On Mon, 2008-04-28 at 13:44 +0200, Michael Kerrisk wrote:
> Hey Peter,
> 
> Ping!

Thanks for the reminder ;-)

> Cheers,
> 
> Michael
> 
> 
> ---------- Forwarded message ----------
> From: Michael Kerrisk <mtk.manpages@xxxxxxxxxxxxxx>
> Date: Fri, Apr 18, 2008 at 6:52 PM
> Subject: RLIMIT_RTTIME documentation for getrlimit.2
> To: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> Cc: Eugene Teo <eugeneteo@xxxxxxxxx>, linux-kernel@xxxxxxxxxxxxxxx,
> Neil Horman <nhorman@xxxxxxxxxxxxx>, Ingo Molnar <mingo@xxxxxxx>,
> linux-man@xxxxxxxxxxxxxxx
> 
> 
> Peter,
> 
> Below is the draft text that I will add to the getrlimit.2 man page to describe
> RLIMIT_RTTIME.  Does it look okay to you?  (I will add a pointer in
> sched_setscheduler.2 to this description in getrlimit.2.)
> 
>       RLIMIT_RTTIME (Since Linux 2.6.25)
>              Specifies a limit on the amount of CPU time that a
>              process  scheduled  under  a  real-time scheduling
>              policy may consume without making a blocking  sys-
>              tem  call.   For  the  purpose of this limit, each
>              time a process makes a blocking system  call,  the
>              count  of  its consumed CPU time is reset to zero.
>              The CPU time count is not  reset  if  the  process
>              continues  trying to use the CPU but is preempted,
>              its   time   slice   expires,    or    it    calls
>              sched_yield(2).
> 
>              Upon  reaching the soft limit, the process is sent
>              a SIGXCPU  signal.   If  the  process  catches  or
>              ignores  this  signal  and continues consuming CPU
>              time, then SIGXCPU will  be  generated  once  each
>              second  until  the hard limit is reached, at which
>              point the process is sent a SIGKILL signal.
> 
>              The intended use of this limit is to stop  a  run-
>              away real-time process from locking up the system.

Looks excellent, thanks!

Acked-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>

in so far that is applicable to man pages ;-)

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