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

[Ingo Molnar]

* KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> wrote:

> > 
> > * Pekka Enberg <penberg@xxxxxxxxxxxxxx> wrote:
> > 
> > > I have no idea how expensive tracepoints are but I suspect they 
> > > don't make too much sense for this particular scenario. After all, 
> > > kmemtrace is mainly interested in _allocation patterns_ whereas 
> > > this patch seems to be more interested in "memory layout" type of 
> > > things.
> > 
> > My point is that the allocation patterns can be derived from dynamic 
> > events. We can build a map of everything if we know all the events 
> > that led up to it. Doing:
> > 
> >   echo 3 > /proc/sys/vm/drop_caches
> > 
> > will clear 99% of the memory allocations, so we can build a new map 
> > from scratch just about anytime. (and if boot allocations are 
> > interesting they can be traced too)
> > 
> > _And_ via this angle we'll also have access to the dynamic events, 
> > in a different 'view' of the same tracepoints - which is obviously 
> > very useful for different purposes.
> 
> I am one of most strongly want guys to MM tracepoint. but No, many 
> cunstomer never permit to use drop_caches.

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.

But it has to be expressed in one framework that cares about the 
totality of the kernel - not just these splintered bits of 
instrumentation and pieces of statistics.

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