Re: [PATCH 5/5] proc: export more page flags in /proc/kpageflags

[Wu Fengguang <fengguang.wu@intel.com>]

On Tue, Apr 28, 2009 at 07:05:53PM +0800, Ingo Molnar wrote:
> 
> * Wu Fengguang <fengguang.wu@intel.com> wrote:
> 
> > > See my other mail i just sent: it would be a natural extension 
> > > of tracing to also dump all current object state when tracing is 
> > > turned on. That way no drop_caches is needed at all.
> > 
> > I can understand the merits here - I also did readahead 
> > tracing/accounting in _one_ piece of code. Very handy.
> > 
> > The readahead traces are now raw printks - converting to the 
> > ftrace framework would be a big win.
> > 
> > But. It's still not a fit-all solution. Imagine when full data 
> > _since_ booting is required, but the user cannot afford a reboot.
> 
> The above 'get object state' interface (which allows passive 
> sampling) - integrated into the tracing framework - would serve that 
> goal, agreed?

Agreed. That could in theory a good complement to dynamic tracings.

Then what will be the canonical form for all the 'get object state'
interfaces - "object.attr=value", or whatever? I'm afraid we will have
to sacrifice efficiency or human readability to have a normalized form.
Or to define two standard forms? One "key value" form and one "value1
value2 value3..." form?

Thanks,
Fengguang