doc: Update CHANGES.rst

CHANGES.rst

@@ -21,6 +21,33 @@ fellow
 
   .. https://gitlab.com/uplex/varnish/slash/-/commit/
 
+* The ``ioerr_obj=purge`` and ``allocerr_obj=purge`` tunables are now
+  fully implemented. The statistics counter ``c_mem_obj_fail`` as been
+  added to track the number of times a failed object is hit.
+
+* Reading cache objects has been made more asynchronous: Segment lists
+  for extended (non-embedded) segments are now read only on demand and
+  in a separate thread.
+
+* Even more memory and disk space allocating functions have been
+  rewritten to use asynchronous allocations to lower latencies.
+
+* Dramatically increased memory efficiency. This change may lead to
+  more memory being shown as free than before, and users of
+  SLASH/fellow may wonder why memory is kept unused: This is a
+  consequence of a deliberate decision in the buddy memory allocator
+  to allocate objects only at multiples of their (rounded up) size,
+  which helps to keep the allocator efficient.
+
+.. _#41: https://gitlab.com/uplex/varnish/slash/-/issues/41
+
+* Dramatically increased stability with minimal memory cache size
+  configurations as long as a correct *objsize_hint* parameter is
+  given (it needs to be *smaller* than the actual average object
+  size). A zero *memsz* argument can now be given to configure the
+  minimal memory cache size, which is NOT RECOMMENDED (the more memory
+  the better). Motivated by `#41`_
+
 * Fixed many bugs
 
 * Improved code coverage and added Coverity for additional linting.