Move android_ids from .data.rel.ro to .rodata
Pages in .data.rel.ro are always dirty. Move whatever we can to
.rodata so that we reduce memory pressure.
The size of rodata, text, and data.rel.ro sections of libc on cuttlefish
before/after this change:
rodata: 0xfd70 -> 0x101d0 (+1120 bytes)
text: 0xb5715 -> 0xb56e5 (-48 bytes)
data.rel.ro: 0x57e0 -> 0x5230 (-1456 bytes)
While this change alone doesn't reduce the number of dirty pages
from data.rel.ro on cuttlefish, it is a step in that direction.
Test: Build and boot cuttlefish
Change-Id: Iff8203940495109dd01c40f31b034cfb2882e7f4
diff --git a/tools/fs_config/fs_config_generator.py b/tools/fs_config/fs_config_generator.py
index cd534ec..f7e3eb2 100755
--- a/tools/fs_config/fs_config_generator.py
+++ b/tools/fs_config/fs_config_generator.py
@@ -1108,9 +1108,14 @@
_INCLUDE = '#include <private/android_filesystem_config.h>'
+ # Note that the android_id name field is of type 'const char[]' instead of
+ # 'const char*'. While this seems less straightforward as we need to
+ # calculate the max length of all names, this allows the entire android_ids
+ # table to be placed in .rodata section instead of .data.rel.ro section,
+ # resulting in less memory pressure.
_STRUCT_FS_CONFIG = textwrap.dedent("""
struct android_id_info {
- const char *name;
+ const char name[%d];
unsigned aid;
};""")
@@ -1132,12 +1137,13 @@
def __call__(self, args):
hdr = AIDHeaderParser(args['hdrfile'])
+ max_name_length = max(len(aid.friendly) + 1 for aid in hdr.aids)
print AIDArrayGen._GENERATED
print
print AIDArrayGen._INCLUDE
print
- print AIDArrayGen._STRUCT_FS_CONFIG
+ print AIDArrayGen._STRUCT_FS_CONFIG % max_name_length
print
print AIDArrayGen._OPEN_ID_ARRAY