LGTM - even though this is a somewhat scary path...
Maybe we should consider putting this behind a flag but have it default to true. This makes it easy to turn it off for testing. The problematic part is that we will never compact the heap again nor free any pages after map space has out-grown the size where map pointers cannot be encoded. We should consider adding compacting of map space (in a new CL) if the number of live maps after a mark-sweep is below the threshold. Kevin has a idea of how to do this: 1. Move maps into the first pages of the map space leaving a forwarding pointer in the moved maps. This can be done using one pointer starting at the beginning of map space and another pointer starting at the end. Sweeping backwards is possible as we know exactly the what is in map space, however the linked list of pages adds some complications. 2. Sweep the heap to make map pointers pointing to a forwarded map point to the new location. 3. Free all the unused pages of map space. http://codereview.chromium.org/507025 -- v8-dev mailing list [email protected] http://groups.google.com/group/v8-dev
