commit 42a82886e1fa1548ceae835e05cf3a503b73695d
author Emily Tucci <etucci@google.com> Wed May 15 21:35:53 2024 +0000
committer CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com> Wed May 15 21:35:53 2024 +0000
tree 45c3c0fef26727d89ce917e24d92734ae3e076cc
parent c7128f5797ce9d44a75ddaa9cd5ce21f02eb2b72

pw_bloat: Add padding to utilization

Used space will increase as multiples of the largest alignment
used in a linker script because padding is added to conform to
the alignment requirements. The new Padding definition should
allow developers to monitor application size change that is
to small to cause realignment.

Test: Included the changes in local project, rebuilt host_gn, and
confirmed Padding was part of the size report generated as part
of local build.
Bug:276370736

Change-Id: Ia9f58f7a6eb4539335d49c4c92979d682bc9278b
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/209972
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
Commit-Queue: Emily Tucci <etucci@google.com>
Reviewed-by: Alexei Frolov <frolv@google.com>

pw_bloat/docs.rst

diff --git a/pw_bloat/docs.rst b/pw_bloat/docs.rst
index ddf08be..f391993 100644
--- a/pw_bloat/docs.rst
+++ b/pw_bloat/docs.rst
@@ -342,6 +342,9 @@
 
 The generated ``utilization`` data source will work with any ELF file, where
 ``Used Space`` is reported for the sum of virtual memory size of all sections.
+``Padding`` captures the amount of memory that is utilized to enfore alignment
+requirements. Tracking ``Padding`` size can help monitor application growth
+for changes that are too small to force realignment.
 
 In order for ``Free Space`` to be reported, your linker scripts must include
 properly aligned sections which span the unused remaining space for the relevant

pw_bloat/py/bloaty_config_test.py

diff --git a/pw_bloat/py/bloaty_config_test.py b/pw_bloat/py/bloaty_config_test.py
index 07c3fe1..0af8e25 100644
--- a/pw_bloat/py/bloaty_config_test.py
+++ b/pw_bloat/py/bloaty_config_test.py
@@ -101,6 +101,10 @@
                 '    replacement:"Free space"',
                 '  }',
                 '  rewrite: {',
+                '    pattern:"^\\\\[LOAD"',
+                '    replacement:"Padding"',
+                '  }',
+                '  rewrite: {',
                 '    pattern:".*"',
                 '    replacement:"Used space"',
                 '  }',

pw_bloat/py/pw_bloat/bloaty_config.py

diff --git a/pw_bloat/py/pw_bloat/bloaty_config.py b/pw_bloat/py/pw_bloat/bloaty_config.py
index 1e3ce31..f149095 100644
--- a/pw_bloat/py/pw_bloat/bloaty_config.py
+++ b/pw_bloat/py/pw_bloat/bloaty_config.py
@@ -341,6 +341,10 @@
     output.append('    replacement:"Free space"')
     output.append('  }')
     output.append('  rewrite: {')
+    output.append('    pattern:"^\\\\[LOAD"')
+    output.append('    replacement:"Padding"')
+    output.append('  }')
+    output.append('  rewrite: {')
     output.append('    pattern:".*"')
     output.append('    replacement:"Used space"')
     output.append('  }')