Improve zygote heap sharing.
[ This is bhayes change 9488 in external "master" ]
Lots of ClassObject structures are unshared [and thus make whole pages
unshared]. A big contributor to this is the initializing class loader
logic, which has two writable words in a ClassObject and does indeed
seem to write them a lot.
Class which are created "early" have a low serial number and are
probably being created by the zygote, and would benefit from better
sharing. This change move the two words for classes with a low serial
number to a global, making the two words in those ClassObjects unused,
and thus more likely to be shared across apps.
Measured increase in sharing is c 100K per app, at a cost of c 32K
increase in unshared globals.
This might be better as a Set<Pair<Class,ClassLoader>> or
something. Many ClassObjects have zero loaders, and the typical count
seems to be very small. It should be possible to remove the two words
from the ClassObject and at the same time have a smaller global data
structure.
Respond to reviewer's comments.
Moved the "external" InitiatingLoaderList[] from gDvm to allocated storage.
Made the warning for the "const" go away.
Remove "vm/Init.c" from the commit
Revert Globals.h to not contain ZYGOTE_CLASS_CUTOFF
Use calloc rather than malloc/clear
3 files changed