Struct mmtk::policy::immix::immixspace::ImmixSpaceArgs

pub struct ImmixSpaceArgs {
    pub unlog_object_when_traced: bool,
    pub reset_log_bit_in_major_gc: bool,
    pub mixed_age: bool,
}

Some arguments for Immix Space.

Fields

unlog_object_when_traced: bool

Mark an object as unlogged when we trace an object. Normally we set the log bit when we copy an object with crate::util::copy::CopySemantics::PromoteToMature. In sticky immix, we ‘promote’ an object to mature when we trace the object (no matter we copy an object or not). So we have to use PromoteToMature, and instead just set the log bit in the space when an object is traced.

reset_log_bit_in_major_gc: bool

Reset log bit at the start of a major GC. Normally we do not need to do this. When immix is used as the mature space, any object should be set as unlogged, and that bit does not need to be cleared even if the object is dead. But in sticky Immix, the mature object and the nursery object are in the same space, we will have to use the bit to differentiate them. So we reset all the log bits in major GCs, and unlogged the objects when they are traced (alive).

mixed_age: bool

Whether this ImmixSpace instance contains both young and old objects. This affects the updating of valid-object bits. If some lines or blocks of this ImmixSpace instance contain young objects, their VO bits need to be updated during this GC. Currently only StickyImmix is affected. GenImmix allocates young objects in a separete CopySpace nursery and its VO bits can be cleared in bulk.