[PATCH v2 0/4] perf script: fix duplicate symbols in db-export

[Chris Phlipot]

Changes since v1:
 - fixed scripts/checkpatch.pl errors

This patch set contains 3 fixes for duplicate symbol creation in the
db-export implementation and one new symbol API required for the fixes.

commit 9c7b37cd63d0 ("perf symbols: Fix handling of zero-length symbols.")
already removed the majority of duplicates, but these fixes take care of
the remaining corner cases.

each patch (except for the 1st, which is a dependency for patch 2) reduces
the number of duplicate symbols exported. When all patches are applied,
my test workload has no more duplicate symbols being exported.

Tests ran:

$perf record --call-graph=dwarf stress -c 2 -t 20
$perf script -s scripts/python/export-to-postgresql.py test all callchains
$psql test

To show the effect of the changes we run the following query before/after
the changes on a database created using the export-to-postgresql.py script
with callchains enabled. If this query returns any value greater than 1,
then it means that there are duplicates present. 


In the test workload, at least one symbol occurs 299 times before applying
the fixes:

  test=# select count(*) as cnt from symbols group by 
	sym_start,sym_end,dso_id order by cnt desc limit 1;
   cnt 
  -----
   299
  (1 row)

After applying the fixes no symbol occurs more than once:

  test=# select count(*) as cnt from symbols group by
	sym_start,sym_end,dso_id order by cnt desc limit 1;
   cnt 
  -----
     1
  (1 row)

Chris Phlipot (4):
  perf symbols: add dso__insert_symbol function
  perf script: fix symbol insertion behavior in db-export
  perf script: fix callchain addresses in db-export
  perf script: fix export of callchains with recursion in db-export

 tools/perf/util/db-export.c | 12 ++++++------
 tools/perf/util/symbol.c    | 12 ++++++++++++
 tools/perf/util/symbol.h    |  3 +++
 3 files changed, 21 insertions(+), 6 deletions(-)

-- 
2.7.4