micropython · dpgeorge · Sep 15, 2023 · Sep 5, 2023 · Sep 5, 2023 · Sep 5, 2023
diff --git a/docs/library/esp32.rst b/docs/library/esp32.rst
@@ -56,15 +56,6 @@ Functions
     two most useful ones are predefined as `esp32.HEAP_DATA` for data heap regions and
     `esp32.HEAP_EXEC` for executable regions as used by the native code emitter.
 
-    Free IDF heap memory in the `esp32.HEAP_DATA` region is available to be
-    automatically added to the MicroPython heap to prevent a MicroPython
-    allocation from failing. However, the information returned here is otherwise
-    *not* useful to troubleshoot Python allocation failures, use
-    `micropython.mem_info()` instead. The "max new split" value in
-    `micropython.mem_info()` output corresponds to the largest free block of
-    ESP-IDF heap that could be automatically added on demand to the MicroPython
-    heap.
-
     The return value is a list of 4-tuples, where each 4-tuple corresponds to one heap
     and contains: the total bytes, the free bytes, the largest free block, and
     the minimum free seen over time.
@@ -75,6 +66,21 @@ Functions
         [(240, 0, 0, 0), (7288, 0, 0, 0), (16648, 4, 4, 4), (79912, 35712, 35512, 35108),
          (15072, 15036, 15036, 15036), (113840, 0, 0, 0)]
 
+    .. note:: Free IDF heap memory in the `esp32.HEAP_DATA` region is available
+       to be automatically added to the MicroPython heap to prevent a
+       MicroPython allocation from failing. However, the information returned
+       here is otherwise *not* useful to troubleshoot Python allocation
+       failures. :func:`micropython.mem_info()` and :func:`gc.mem_free()` should
+       be used instead:
+
+       The "max new split" value in :func:`micropython.mem_info()` output
+       corresponds to the largest free block of ESP-IDF heap that could be
+       automatically added on demand to the MicroPython heap.
+
+       The result of :func:`gc.mem_free()` is the total of the current "free"
+       and "max new split" values printed by :func:`micropython.mem_info()`.
+
+
 Flash partitions
 ----------------
 

diff --git a/docs/library/gc.rst b/docs/library/gc.rst
@@ -24,7 +24,7 @@ Functions
 
 .. function:: mem_alloc()
 
-   Return the number of bytes of heap RAM that are allocated.
+   Return the number of bytes of heap RAM that are allocated by Python code.
 
    .. admonition:: Difference to CPython
       :class: attention
@@ -33,8 +33,8 @@ Functions
 
 .. function:: mem_free()
 
-   Return the number of bytes of available heap RAM, or -1 if this amount
-   is not known.
+   Return the number of bytes of heap RAM that is available for Python
+   code to allocate, or -1 if this amount is not known.
 
    .. admonition:: Difference to CPython
       :class: attention

diff --git a/py/gc.c b/py/gc.c
@@ -701,6 +701,11 @@ void gc_info(gc_info_t *info) {
 
     info->used *= BYTES_PER_BLOCK;
     info->free *= BYTES_PER_BLOCK;
+
+    #if MICROPY_GC_SPLIT_HEAP_AUTO
+    info->max_new_split = gc_get_max_new_split();
+    #endif
+
     GC_EXIT();
 }
 
@@ -1159,7 +1164,7 @@ void gc_dump_info(const mp_print_t *print) {
     mp_printf(print, "GC: total: %u, used: %u, free: %u",
         (uint)info.total, (uint)info.used, (uint)info.free);
     #if MICROPY_GC_SPLIT_HEAP_AUTO
-    mp_printf(print, ", max new split: %u", (uint)gc_get_max_new_split());
+    mp_printf(print, ", max new split: %u", (uint)info.max_new_split);
     #endif
     mp_printf(print, "\n No. of 1-blocks: %u, 2-blocks: %u, max blk sz: %u, max free sz: %u\n",
         (uint)info.num_1block, (uint)info.num_2block, (uint)info.max_block, (uint)info.max_free);

diff --git a/py/gc.h b/py/gc.h
@@ -75,6 +75,9 @@ typedef struct _gc_info_t {
     size_t num_1block;
     size_t num_2block;
     size_t max_block;
+    #if MICROPY_GC_SPLIT_HEAP_AUTO
+    size_t max_new_split;
+    #endif
 } gc_info_t;
 
 void gc_info(gc_info_t *info);

diff --git a/py/modgc.c b/py/modgc.c
@@ -64,7 +64,12 @@ MP_DEFINE_CONST_FUN_OBJ_0(gc_isenabled_obj, gc_isenabled);
 STATIC mp_obj_t gc_mem_free(void) {
     gc_info_t info;
     gc_info(&info);
+    #if MICROPY_GC_SPLIT_HEAP_AUTO
+    // Include max_new_split value here as a more useful heuristic
+    return MP_OBJ_NEW_SMALL_INT(info.free + info.max_new_split);
+    #else
     return MP_OBJ_NEW_SMALL_INT(info.free);
+    #endif
 }
 MP_DEFINE_CONST_FUN_OBJ_0(gc_mem_free_obj, gc_mem_free);