Re: perf monitoring triggers Was: Re: [tip:perf/core] perf bench: Print both of prefaulted and no prefaulted results by default

[Peter Zijlstra <a.p.zijlstra@chello.nl>]

On Mon, 2010-12-13 at 10:38 -0200, Arnaldo Carvalho de Melo wrote:
> Em Mon, Dec 13, 2010 at 12:14:33PM +0100, Peter Zijlstra escreveu:
> > On Sun, 2010-12-12 at 11:46 -0200, Arnaldo Carvalho de Melo wrote:
> > > Looks interesting, and also interesting would be to be able to place
> > > probes that would wake up it too, for unmodified binaries to have
> > > something similar.
> 
> > > Other kinds of triggers may be to hook on syscalls and when some
> > > expression matches, like connecting to host 1.2.3.4, start monitoring,
> > > stop when the socket is closed, i.e. monitor a connection lifetime, etc.
>  
> > Sounds to me like you want something like a library with self-monitoring
> > stuff.
> 
> Yeah, that could be a way, an LD_PRELOAD thingy that would intercept
> library calls, setup counters, start a monitoring thread, etc.
> 
> Along the lines of:
> 
> http://git.kernel.org/?p=linux/kernel/git/acme/libautocork.git;a=blob;f=libautocork.c
> 
> This one just intercepts calls, but the __init function could do the
> rest.
> 
> To make it easier we could move the counter setup we have in record/top
> to a library, etc.

Nah, I was more thinking of something along the lines of libPAPI and
libpfmon. A library that contains the needed building blocks for apps to
profile themselves.