Question

As I know Dalvik VM does not support generational GC as default.

But, I found “WITH_OBJECT_HEADERS” compilation flag which could be related with generational GC from HeapInternal.h file.

typedef struct DvmHeapChunk {
#if WITH_OBJECT_HEADERS
    u4 header;
    const Object *parent;
    const Object *parentOld;
    const Object *markFinger;
    const Object *markFingerOld;
    u2 birthGeneration;
    u2 markCount;
    u2 scanCount;
    u2 oldMarkGeneration;
    u2 markGeneration;
    u2 oldScanGeneration;
    u2 scanGeneration;
#endif

Does anyone try to build Dalvik with this option enabled? Do you know anything about generational GC support from Dalvik?

Answer 1

This was part of an experiment. There is no generational GC support in the current release. Improvements to the GC will be part of a future release.