lkml.org 
[lkml]   [2006]   [Apr]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: PREEMPT_RT : 2.6.16-rt12 and boot : BUG ?
Date
mercredi 12 Avril 2006 08:25, you wrote/vous avez écrit :
>
> * Steven Rostedt <rostedt@goodmis.org> wrote:
>
> > > Why do we need such a size ?
> >
> > It seems that the -rt kernel has increased the size of structures that
> > are used in modules and are defined per cpu.
>
> i'm still wondering what that could be. The most drastic increase is the
> size of locks (spinlocks, mutexes, etc.), especially with debugging
> enabled - maybe one of the drivers uses a big per-CPU array of locks?
>
> ah. One thing that takes up _alot_ of per-CPU space is the
> latency-histogram stuff. I made the latency tracer itself use
> non-per-cpu constructs to avoid overflowing the per-cpu-area, but the
> latency-histogram code still uses PER_CPU:
>
...
>
> where MAX_ENTRY_NUM is 10240 right now. So the space used up is
> 10240*3*8 - roughly +256K per-cpu space!
I use effectively CONFIG_WAKEUP_LATENCY_HIST.
>
> I think that explains it. So the rule for -rt is, +256K more per-cpu
> area is needed if the latency histograms are turned on.
OK.
>
> Ingo

--
Serge Noiraud
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2006-04-12 09:25    [W:0.044 / U:0.696 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site