Re: [PATCH 5/6] perf_counter: kerneltop: mmap_pages argument

From: Ingo Molnar
Date: Wed Mar 25 2009 - 08:54:29 EST



* Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> wrote:

> On Wed, 2009-03-25 at 13:35 +0100, Ingo Molnar wrote:
>
> > > Also, when mixing streams (events,mmap) is a single: you missed
> > > 'n' events still good?
> >
> > How would such mixing work? Multiple counters streaming into the
> > same mmap area?
>
> No basically having overflow events and mmap-vma changed events in
> a single output stream.

ah, and i missed the impact of variable size records - that too
makes it somewhat impractical to emit overflow records in situ. (the
kernel does not really know the precise start of the previous
record, typically.)

Ingo
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