[autoparallel] user-friendly API for CheckpointSolver. (#1879)

Merge for SC tutorial

colossalai/auto_parallel/checkpoint/ckpt_solver_base.py

@@ -2,6 +2,7 @@ from abc import ABC, abstractmethod
 from copy import deepcopy
 from typing import Any, List
 
+import torch
 from torch.fx import Graph, Node
 
 from colossalai.fx.codegen.activation_checkpoint_codegen import ActivationCheckpointCodeGen
@@ -17,13 +18,17 @@ def _copy_output(src: Graph, dst: Graph):
             n_dst.meta = n_src.meta
 
 
+def _get_param_size(module: torch.nn.Module):
+    """Get the size of the parameters in the module"""
+    return sum([p.numel() * torch.tensor([], dtype=p.dtype).element_size() for p in module.parameters()])
+
+
 class CheckpointSolverBase(ABC):
 
     def __init__(
         self,
         graph: Graph,
-        memory_budget: float = -1.0,
-        parameter_size: float = 0,
+        free_memory: float = -1.0,
         requires_linearize: bool = False,
         cnode: List[str] = None,
     ):
@@ -37,8 +42,7 @@ class CheckpointSolverBase(ABC):
 
         Args:
             graph (Graph): The computing graph to be optimized.
-            memory_budget (float): Memory constraint for the solution.
-            parameter_size (float): The size of parameter of this model. Use `parameter_size(model)` to estimate.
+            free_memory (float): Memory constraint for the solution.
             requires_linearize (bool): Whether the graph needs to be linearized.
             cnode (List[str], optional): Common node List, should be the subset of input. Default to None.
 
@@ -58,8 +62,8 @@ class CheckpointSolverBase(ABC):
             raise RuntimeError(
                 "Nodes meta information hasn't been prepared! Please run MetaInfoProp before constructing the solver!")
 
-        self.memory_budget = memory_budget
-        self.parameter_size = parameter_size
+        self.free_memory = free_memory
+        self.parameter_size = _get_param_size(self.graph.owning_module)
         self.cnode = cnode
         self.requires_linearize = requires_linearize
         if self.requires_linearize:

colossalai/auto_parallel/checkpoint/ckpt_solver_rotor.py

@@ -22,12 +22,7 @@ __all__ = ['CheckpointSolverRotor']
 
 class CheckpointSolverRotor(CheckpointSolverBase):
 
-    def __init__(self,
-                 graph: Graph,
-                 memory_budget: float = -1,
-                 parameter_size: float = 0,
-                 cnode: List[str] = None,
-                 memory_slots: int = 500):
+    def __init__(self, graph: Graph, free_memory: float = -1, cnode: List[str] = None, memory_slots: int = 500):
         """This is the simple implementation of dynamic programming algorithm rotor
         in https://hal.inria.fr/hal-02352969. Some code are adapted from
         https://gitlab.inria.fr/hiepacs/rotor.
@@ -36,22 +31,22 @@ class CheckpointSolverRotor(CheckpointSolverBase):
             Assume that we have a `GraphModule`, and we already applied the `MetaInfoProp`
             to the graph to retrieve all information needed, then we could use the following
             code to find a solution using `CheckpointSolverRotor`:
-            >>> solver = CheckpointSolverRotor(gm.graph, memory_budget=memory_budget, parameter_size=parameter_size)
+            >>> solver = CheckpointSolverRotor(gm.graph, free_memory=torch.cuda.mem_get_info(device=0)[0])
             >>> rotor_graph = solver.solve(force_python=True)   # otherwise use C solver
             >>> gm.graph = rotor_graph    # set the graph to a new graph
 
         Args:
             graph (Graph): The computing graph to be optimized.
-            memory_budget (float, optional): Memory constraint for the solution, unit is byte.
-            parameter_size (float, optional): The size of parameter of this model, unit is byte. Use `parameter_size(model)` to estimate.
+            free_memory (float, optional): Memory constraint for the solution, unit is byte.
+                Use ``torch.cuda.mem_get_info(device=0)[0]`` to estimate the free_memory. Defaults to -1.
             cnode (List[str], optional): Common node List, should be the subset of input. Defaults to None.
             memory_slots (int, optional): Number of slots for discretizing memory budget. Defaults to 500.
         """
-        super().__init__(graph, memory_budget, parameter_size, True, cnode)
+        super().__init__(graph, free_memory, True, cnode)
         self.memory_slots = memory_slots
 
         # construct chain
-        unit = self.memory_budget // self.memory_slots
+        unit = self.free_memory // self.memory_slots
         self.chain = self._construct_chain(self.graph, self.node_list)
         self.chain.discretize_all(unit)