* Mel Gorman <mel@csn.ul.ie> wrote:

quoted text
> > > Nice one Ingo - got it first try. The problem commit was 
> > > dd41f596cda0d7d6e4a8b139ffdfabcefdd46528 and it's clear that the 
> > > code removed in this commit is put back by this latest patch.  
> > > When applied, profile=sleep works as long as CONFIG_SCHEDSTAT is 
> > > set.
> > > 
> > And if it isn't set? I can easily see building a new kernel with 
> > stats off and forgetting to change the boot options.
> 
> If CONFIG_SCHEDSTAT is off and profile=sleep is set, you see with 
> Ingo's patch and readprofile;
> 
>      0 *unknown*
>      0 total                                      0.0000
> 
> That is a tad confusing hence my follow-up patch which would say 
> "/proc/profile" doesn't exist when readprofile is used and the warning 
> in dmesg.

yep - that's the best we can do for the stable release.

We could improve quality of behavior here by not offering /proc/profile 
in that case and by printk-ing something if profile=sleep is specified 
on a !CONFIG_SCHEDSTATS kernel. I'm willing to apply patches that do 
that :)

	Ingo
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