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

[Pekka Enberg]

Hi Ingo,

On Tue, 2009-04-28 at 09:40 +0200, Andi Kleen wrote:
>> > > I think i have to NAK this kind of ad-hoc instrumentation of kernel
>> > > internals and statistics until we clear up why such instrumentation

* Pekka Enberg <penberg@xxxxxxxxxxxxxx> wrote:
>> > I think because it has zero fast path overhead and can be used
>> > any time without enabling anything special.

On Tue, Apr 28, 2009 at 12:15 PM, Ingo Molnar <mingo@xxxxxxx> wrote:
> ( That's a dubious claim in any case - tracepoints are very cheap.
>  And they could be made even cheaper and such efforts would benefit
>  all the tracepoint users so it's a prime focus of interest.
>  Andi is a SystemTap proponent, right? I saw him oppose pretty much
>  everything built-in kernel tracing related. I consider that a
>  pretty extreme position. )

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.

                                                Pekka
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