perf userspace tools fixes for Ubuntu / linaro

[Dave Martin]

Hi there,

I worked on a few patches to the help the userspace perf tools do
better at loading debug symbols -- this is particularly of interest on
Ubuntu and Linaro where separated debug symbols in .ddebs are
typically not loaded even when present.  Note that even with the
patches, the contents of .ddebs are still not cached by perf along
with the other profiled binaries, so you will still lose the symbols
if you uninstall/upgrade your ddebs in the meantime.  This should get
fixed in the future.

Due to mailserver issues, Arnaldo kindly helped merge these patches
for me.  The patches are now merged to the linux-2.6-tip master
branch.


You can find details of the commits here:

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/608775


[ Nico: WIll says he's going to pull these patches into his linaro
branch, if it's more convenient for you to pull from there. ]

Covering notes explaining the changes follow.

Cheers
---Dave


>From c1cb454cc818d367e6b679600bbe7c2fc6d75c2c Mon Sep 17 00:00:00 2001
From: Dave Martin <dave.martin at linaro.org>
Date: Tue, 27 Jul 2010 16:44:36 +0100
Subject: [PATCH 0/2] tools/perf: Fix debug symbol lookup issues for some OSes

On Ubuntu (and some other OSes) debug symbols for most of the binaries are
split out into separately-installable files under /usr/lib/debug or elsewhere.

perf already supports this setup, but as a side-effect of abbreviating the
prefix of paths beneath the current directory to './' for display purposes,
the paths constructed to search for the separate debug images are incorrect.

As a result, symbols may not be found even if they are available.

The simplest fix seems to be just to remove the cwd abbreviation feature; this
makes all displayed paths absolute in e.g., perf report -v, but otherwise
appears harmless.

Dave Martin (2):
  tools/perf: Don't abbreviate file paths relative to the cwd
  tools/perf: Remove unneeded code for tracking the cwd in perf
    sessions

 tools/perf/util/event.c   |    2 +-
 tools/perf/util/map.c     |   22 +---------------------
 tools/perf/util/map.h     |    2 +-
 tools/perf/util/session.c |   22 +---------------------
 4 files changed, 4 insertions(+), 44 deletions(-)


>From fa6c691b767bfcdf9a704aeab58ddc6f618b9be8 Mon Sep 17 00:00:00 2001
From: Dave Martin <dave.martin at linaro.org>
Date: Fri, 30 Jul 2010 12:31:46 +0100
Subject: [PATCH 0/3] perf tools: Better image search for separated debug images

The perf tools' buildid cache functionality currently interferes with
loading the correct symbols in environments which use separated debug
images (Ubuntu, Fedora, ...)

This patch set modifies the image search behaviour to perform 2 passes:
no image without a full symtab is considered for loading unless no
image with a symtab is available at all.  This avoids loading images
from the buildid cache if a better image is available elsewhere.  As a
consequence, perf report and friends should now load the correct
symbols on Ubuntu and friends, at the cost of an extra image loading
pass.

This patch set does not change the way files get cached, but ought to
be OK as the basis for further refactoring to replicate the same search
behaviour in the caching code so all relevant images get cached.

The extra image loading pass should not need to occur on the common path
once the caching behaviour modifications are done.

Dave Martin (3):
  perf tools: Factor out buildid reading and make it implicit in
    dso__load
  perf tools: remove extra build-id check factored into dso__load
  perf tools: improve debug image search when loading symbols

 tools/perf/util/symbol.c |  206 +++++++++++++++++++++++++--------------------
 1 files changed, 114 insertions(+), 92 deletions(-)