Re: [PATCH 1/2] Add trace points to mmap, munmap, and brk

From: KOSAKI Motohiro
Date: Tue Jul 27 2010 - 07:17:15 EST

> On Wed, 21 Jul 2010, KOSAKI Motohiro wrote:
> > > This patch adds trace points to mmap, munmap, and brk that will report
> > > relevant addresses and sizes before each function exits successfully.
> > >
> > > Signed-off-by: Eric B Munson <emunson@xxxxxxxxx>
> >
> > I don't think this is good idea. if you need syscall result, you should
> > use syscall tracer. IOW, This tracepoint bring zero information.
> >
> > Please see perf_event_mmap() usage. Our kernel manage adress space by
> > vm_area_struct. we need to trace it if we need to know what kernel does.
> >
> > Thanks.
> The syscall tracer does not give you the address and size of the mmaped areas
> so this does provide information above simply tracing the enter/exit points
> for each call.

Why don't you fix this?

> perf_event_mmap does provide the information for mmap calls. Originally I sent
> a patch to add a trace point to munmap and Peter Z asked for corresponding points
> in the mmap family. If the consensus is that the trace point in munmap is the
> only one that should be added I can resend that patch.
> --
> Eric B Munson
> IBM Linux Technology Center
> ebmunson@xxxxxxxxxx

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