• Damien George's avatar
    py: Improve allocation policy of qstr data. · ade9a052
    Damien George authored
    Previous to this patch all interned strings lived in their own malloc'd
    chunk.  On average this wastes N/2 bytes per interned string, where N is
    the number-of-bytes for a quanta of the memory allocator (16 bytes on 32
    bit archs).
    With this patch interned strings are concatenated into the same malloc'd
    chunk when possible.  Such chunks are enlarged inplace when possible,
    and shrunk to fit when a new chunk is needed.
    RAM savings with this patch are highly varied, but should always show an
    improvement (unless only 3 or 4 strings are interned).  New version
    typically uses about 70% of previous memory for the qstr data, and can
    lead to savings of around 10% of total memory footprint of a running
    Costs about 120 bytes code size on Thumb2 archs (depends on how many
    calls to gc_realloc are made).