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

* KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote:

> >
> > * Pekka Enberg <penberg@cs.helsinki.fi> 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


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