So that we don't have to pass it around to the several methods that
needs it, simplifying usage.

There is one case where we don't have the thread/cpu map in advance,
which is in the parsing routines used by top, stat, record, that we have
to wait till all options are parsed to know if a cpu or thread list was
passed to then create those maps.

For that case consolidate the cpu and thread map creation via
perf_evlist__create_maps() out of the code in top and record, while also
providing a perf_evlist__set_maps() for cases where multiple evlists
share maps or for when maps that represent CPU sockets, for instance,
get crafted out of topology information or subsets of threads in a
particular application are to be monitored, providing more granularity
in specifying which cpus and threads to monitor.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

First clarifying that this kind of binding is not a replacement or an
equivalent to the 'perf script' way of using python with perf.

The 'perf script' way is to process events and look at a given script
for some python function that matches the events to pass each event for
processing.

This is a python module, i.e. everything is driven from the python
script, that merely uses "import perf" or "from perf import".

perf script is focused on tracepoints, this binding is focused on profiling as
an initial target. More work is needed to make available tracepoint specific
variables as event variables accessible via this binding.

There is one example of such usage model, in
tools/perf/python/twatch.py, a tool to watch "cycles" events together
with task (fork, exit) and comm perf events.

For now, due to me not being able to grok how python distutils cope with
building C extensions outside the sources dir the install target just
builds it, I'm using it as:

[root@emilia linux]# export PYTHONPATH=~acme/git/build/perf/lib.linux-x86_64-2.6/
[root@emilia linux]# tools/perf/python/twatch.py
cpu:  4, pid: 30126, tid: 30126 { type: mmap, pid: 30126, tid: 30126, start: 0x4, length: 0x82e9ca03, offset: 0, filename:  }
cpu:  6, pid:   47, tid:   47 { type: mmap, pid: 47, tid: 47, start: 0x6, length: 0xbef87c36, offset: 0, filename:  }
cpu:  1, pid:    0, tid:    0 { type: mmap, pid: 0, tid: 0, start: 0x1, length: 0x775d1904, offset: 0, filename:  }
cpu:  7, pid:    0, tid:    0 { type: mmap, pid: 0, tid: 0, start: 0x7, length: 0xc750aeb6, offset: 0, filename:  }
cpu:  5, pid: 2255, tid: 2255 { type: mmap, pid: 2255, tid: 2255, start: 0x5, length: 0x76669635, offset: 0, filename:  }
cpu:  0, pid:    0, tid:    0 { type: mmap, pid: 0, tid: 0, start: 0, length: 0x6422ef6b, offset: 0, filename:  }
cpu:  2, pid: 2255, tid: 2255 { type: mmap, pid: 2255, tid: 2255, start: 0x2, length: 0xe078757a, offset: 0, filename:  }
cpu:  1, pid: 5769, tid: 5769 { type: fork, pid: 30127, ppid: 5769, tid: 30127, ptid: 5769, time: 103893991270534}
cpu:  6, pid: 30127, tid: 30127 { type: comm, pid: 30127, tid: 30127, comm: ls }
cpu:  6, pid: 30127, tid: 30127 { type: exit, pid: 30127, ppid: 30127, tid: 30127, ptid: 30127, time: 103893993273024}

The first 8 mmap events in this 8 way machine are a mistery that is still being
investigated.

More of the tools/perf/util/ APIs will be exposed via this python binding as
the need arises. For now the focus is on creating events and processing them,
symbol resolution is an obvious next step, with tracepoint variables as a close
second step.

Cc: Clark Williams <williams@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>