[PATCH] perf diff: bug fix, donot overwrite valid build id

[PATCH] perf diff: bug fix, donot overwrite valid build id

[kan.liang]

From: Kan Liang <kan.liang@intel.com>

Fixes a perf diff regression issue which was introduced by
commit 5baecbcd9c9a ("perf symbols: we can now read separate debug-info
files based on a build ID")

The binary name could be same when perf diff different binaries. Build
id is used to distinguish between them.
However, the previous patch assumes the same binary name has same build
id. So it overwrites the build id according to the binary name,
regardless of whether the build id is set or not.

Check the has_build_id in dso__load. If the build id is already set, use
it.

Before the fix applies,
 sudo ./perf diff 1.perf.data 2.perf.data
 # Event 'cycles'
 #
 # Baseline    Delta  Shared Object     Symbol
 # ........  .......  ................  .............................
 #
    99.83%  -99.80%  tchain_edit       [.] f2
     0.12%  +99.81%  tchain_edit       [.] f3
     0.02%   -0.01%  [ixgbe]           [k] ixgbe_read_reg

After the fix applies,
 sudo ./perf diff 1.perf.data 2.perf.data
 # Event 'cycles'
 #
 # Baseline    Delta  Shared Object     Symbol
 # ........  .......  ................  .............................
 #
    99.83%   +0.10%  tchain_edit       [.] f3
     0.12%   -0.08%  tchain_edit       [.] f2

Signed-off-by: Kan Liang <kan.liang@intel.com>
---
 tools/perf/util/symbol.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index df2482b..dc93940 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1459,7 +1459,8 @@ int dso__load(struct dso *dso, struct map *map)
 	 * Read the build id if possible. This is required for
 	 * DSO_BINARY_TYPE__BUILDID_DEBUGINFO to work
 	 */
-	if (is_regular_file(dso->long_name) &&
+	if (!dso->has_build_id &&
+	    is_regular_file(dso->long_name) &&
 	    filename__read_build_id(dso->long_name, build_id, BUILD_ID_SIZE) > 0)
 		dso__set_build_id(dso, build_id);
 
-- 
2.4.3

RE: [PATCH] perf diff: bug fix, donot overwrite valid build id

[Liang, Kan]

Hi Arnaldo,

Ping

Are you OK with the fix?

Thanks,
Kan

> 
> From: Kan Liang <kan.liang@intel.com>
> 
> Fixes a perf diff regression issue which was introduced by commit
> 5baecbcd9c9a ("perf symbols: we can now read separate debug-info files
> based on a build ID")
> 
> The binary name could be same when perf diff different binaries. Build id is
> used to distinguish between them.
> However, the previous patch assumes the same binary name has same
> build id. So it overwrites the build id according to the binary name,
> regardless of whether the build id is set or not.
> 
> Check the has_build_id in dso__load. If the build id is already set, use it.
> 
> Before the fix applies,
>  sudo ./perf diff 1.perf.data 2.perf.data  # Event 'cycles'
>  #
>  # Baseline    Delta  Shared Object     Symbol
>  # ........  .......  ................  .............................
>  #
>     99.83%  -99.80%  tchain_edit       [.] f2
>      0.12%  +99.81%  tchain_edit       [.] f3
>      0.02%   -0.01%  [ixgbe]           [k] ixgbe_read_reg
> 
> After the fix applies,
>  sudo ./perf diff 1.perf.data 2.perf.data  # Event 'cycles'
>  #
>  # Baseline    Delta  Shared Object     Symbol
>  # ........  .......  ................  .............................
>  #
>     99.83%   +0.10%  tchain_edit       [.] f3
>      0.12%   -0.08%  tchain_edit       [.] f2
> 
> Signed-off-by: Kan Liang <kan.liang@intel.com>
> ---
>  tools/perf/util/symbol.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c index
> df2482b..dc93940 100644
> --- a/tools/perf/util/symbol.c
> +++ b/tools/perf/util/symbol.c
> @@ -1459,7 +1459,8 @@ int dso__load(struct dso *dso, struct map *map)
>  	 * Read the build id if possible. This is required for
>  	 * DSO_BINARY_TYPE__BUILDID_DEBUGINFO to work
>  	 */
> -	if (is_regular_file(dso->long_name) &&
> +	if (!dso->has_build_id &&
> +	    is_regular_file(dso->long_name) &&
>  	    filename__read_build_id(dso->long_name, build_id,
> BUILD_ID_SIZE) > 0)
>  		dso__set_build_id(dso, build_id);
> 
> --
> 2.4.3

Re: [PATCH] perf diff: bug fix, donot overwrite valid build id

[acme]

Em Mon, Dec 19, 2016 at 02:53:30PM +0000, Liang, Kan escreveu:
> Hi Arnaldo,
> 
> Ping
> 
> Are you OK with the fix?

Yeah, looks ok, will merge it.

- Arnaldo
 
> Thanks,
> Kan
> 
> > 
> > From: Kan Liang <kan.liang@intel.com>
> > 
> > Fixes a perf diff regression issue which was introduced by commit
> > 5baecbcd9c9a ("perf symbols: we can now read separate debug-info files
> > based on a build ID")
> > 
> > The binary name could be same when perf diff different binaries. Build id is
> > used to distinguish between them.
> > However, the previous patch assumes the same binary name has same
> > build id. So it overwrites the build id according to the binary name,
> > regardless of whether the build id is set or not.
> > 
> > Check the has_build_id in dso__load. If the build id is already set, use it.
> > 
> > Before the fix applies,
> >  sudo ./perf diff 1.perf.data 2.perf.data  # Event 'cycles'
> >  #
> >  # Baseline    Delta  Shared Object     Symbol
> >  # ........  .......  ................  .............................
> >  #
> >     99.83%  -99.80%  tchain_edit       [.] f2
> >      0.12%  +99.81%  tchain_edit       [.] f3
> >      0.02%   -0.01%  [ixgbe]           [k] ixgbe_read_reg
> > 
> > After the fix applies,
> >  sudo ./perf diff 1.perf.data 2.perf.data  # Event 'cycles'
> >  #
> >  # Baseline    Delta  Shared Object     Symbol
> >  # ........  .......  ................  .............................
> >  #
> >     99.83%   +0.10%  tchain_edit       [.] f3
> >      0.12%   -0.08%  tchain_edit       [.] f2
> > 
> > Signed-off-by: Kan Liang <kan.liang@intel.com>
> > ---
> >  tools/perf/util/symbol.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c index
> > df2482b..dc93940 100644
> > --- a/tools/perf/util/symbol.c
> > +++ b/tools/perf/util/symbol.c
> > @@ -1459,7 +1459,8 @@ int dso__load(struct dso *dso, struct map *map)
> >  	 * Read the build id if possible. This is required for
> >  	 * DSO_BINARY_TYPE__BUILDID_DEBUGINFO to work
> >  	 */
> > -	if (is_regular_file(dso->long_name) &&
> > +	if (!dso->has_build_id &&
> > +	    is_regular_file(dso->long_name) &&
> >  	    filename__read_build_id(dso->long_name, build_id,
> > BUILD_ID_SIZE) > 0)
> >  		dso__set_build_id(dso, build_id);
> > 
> > --
> > 2.4.3

[tip:perf/urgent] perf diff: Do not overwrite valid build id

[tip-bot for Kan Liang]

Commit-ID:  ed6c166cc7dc329736cace3affd2df984fb22ec8
Gitweb:     http://git.kernel.org/tip/ed6c166cc7dc329736cace3affd2df984fb22ec8
Author:     Kan Liang <kan.liang@intel.com>
AuthorDate: Tue, 13 Dec 2016 10:29:44 -0500
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Tue, 20 Dec 2016 12:00:38 -0300

perf diff: Do not overwrite valid build id

Fixes a perf diff regression issue which was introduced by commit
5baecbcd9c9a ("perf symbols: we can now read separate debug-info files
based on a build ID")

The binary name could be same when perf diff different binaries. Build
id is used to distinguish between them.
However, the previous patch assumes the same binary name has same build
id. So it overwrites the build id according to the binary name,
regardless of whether the build id is set or not.

Check the has_build_id in dso__load. If the build id is already set, use
it.

Before the fix:

  $ perf diff 1.perf.data 2.perf.data
  # Event 'cycles'
  #
  # Baseline    Delta  Shared Object     Symbol
  # ........  .......  ................  .............................
  #
    99.83%  -99.80%  tchain_edit       [.] f2
     0.12%  +99.81%  tchain_edit       [.] f3
     0.02%   -0.01%  [ixgbe]           [k] ixgbe_read_reg

  After the fix:
  $ perf diff 1.perf.data 2.perf.data
  # Event 'cycles'
  #
  # Baseline    Delta  Shared Object     Symbol
  # ........  .......  ................  .............................
  #
    99.83%   +0.10%  tchain_edit       [.] f3
     0.12%   -0.08%  tchain_edit       [.] f2

Signed-off-by: Kan Liang <kan.liang@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
CC: Dima Kogan <dima@secretsauce.net>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Fixes: 5baecbcd9c9a ("perf symbols: we can now read separate debug-info files based on a build ID")
Link: http://lkml.kernel.org/r/1481642984-13593-1-git-send-email-kan.liang@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/symbol.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index df2482b..dc93940 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1459,7 +1459,8 @@ int dso__load(struct dso *dso, struct map *map)
 	 * Read the build id if possible. This is required for
 	 * DSO_BINARY_TYPE__BUILDID_DEBUGINFO to work
 	 */
-	if (is_regular_file(dso->long_name) &&
+	if (!dso->has_build_id &&
+	    is_regular_file(dso->long_name) &&
 	    filename__read_build_id(dso->long_name, build_id, BUILD_ID_SIZE) > 0)
 		dso__set_build_id(dso, build_id);