More additions to Kron

timm/optim/kron.py

@@ -15,15 +15,6 @@ from typing import Any, Callable, Dict, Optional, Tuple, Union
 import numpy as np
 import torch
 
-try:
-    # NOTE opt_einsum needed to avoid blowing up memory with einsum ops
-    import opt_einsum
-    opt_einsum.enabled = True
-    opt_einsum.strategy = "auto-hq"
-    import torch.backends.opt_einsum
-    has_opt_einsum = True
-except ImportError:
-    has_opt_einsum = False
 
 try:
     torch._dynamo.config.cache_size_limit = 1_000_000
@@ -67,19 +58,20 @@ class Kron(torch.optim.Optimizer):
         params: Iterable of parameters to optimize or dicts defining parameter groups.
         lr: Learning rate.
         momentum: Momentum parameter.
-        weight_decay: Weight decay (L2 penalty).
+        weight_decay: Weight decay.
         preconditioner_update_probability: Probability of updating the preconditioner.
             If None, defaults to a schedule that anneals from 1.0 to 0.03 by 4000 steps.
         max_size_triangular: Max size for dim's preconditioner to be triangular.
         min_ndim_triangular: Minimum number of dimensions a layer needs to have triangular preconditioners.
-        memory_save_mode: 'one_diag', or 'all_diag', None is default
+        memory_save_mode: 'one_diag', 'smart_one_diag', or 'all_diag', None is default
             to set all preconditioners to be triangular, 'one_diag' sets the largest
             or last dim to be diagonal per layer, and 'all_diag' sets all preconditioners to be diagonal.
         momentum_into_precond_update: whether to send momentum into preconditioner
             update instead of raw gradients.
         mu_dtype: Dtype of the momentum accumulator.
         precond_dtype: Dtype of the preconditioner.
-        decoupled_decay: AdamW style decoupled-decay.
+        decoupled_decay: AdamW style decoupled weight decay
+        flatten_dim: Flatten dim >= 2 instead of relying on expressions
         deterministic: Deterministic behaviour across save / load (resume). FIXME slow, needs work
     """
 
@@ -97,10 +89,18 @@ class Kron(torch.optim.Optimizer):
         mu_dtype: Optional[torch.dtype] = None,
         precond_dtype: Optional[torch.dtype] = None,
         decoupled_decay: bool = False,
+        flatten_dim: bool = False,
         deterministic: bool = False,
     ):
-        if not has_opt_einsum:
+        try:
+            # NOTE opt_einsum needed to avoid blowing up memory with einsum ops
+            import opt_einsum
+            opt_einsum.enabled = True
+            opt_einsum.strategy = "auto-hq"
+            import torch.backends.opt_einsum
+        except ImportError:
             warnings.warn("It is highly recommended to have 'opt_einsum' installed for this optimizer." )
+
         if not 0.0 <= lr:
             raise ValueError(f"Invalid learning rate: {lr}")
         if not 0.0 <= momentum < 1.0:
@@ -122,10 +122,11 @@ class Kron(torch.optim.Optimizer):
             mu_dtype=mu_dtype,
             precond_dtype=precond_dtype,
             decoupled_decay=decoupled_decay,
+            flatten_dim=flatten_dim,
         )
         super(Kron, self).__init__(params, defaults)
 
-        self._param_exprs = {}
+        self._param_exprs = {}  # cache for einsum expr
         self._tiny = torch.finfo(torch.bfloat16).tiny
         self.rng = random.Random(1337)
         if deterministic:
@@ -165,20 +166,21 @@ class Kron(torch.optim.Optimizer):
 
     def load_state_dict(self, state_dict: Dict[str, Any]) -> None:
         # Extract and remove the RNG state from the state dict
-        rng_state = state_dict.pop('rng_state', None)
-        torch_rng_state = state_dict.pop('torch_rng_state', None)
+        rng_states = {}
+        if 'rng_state' in state_dict:
+            rng_states['rng_state'] = state_dict.pop('rng_state')
+        if 'torch_rng_state' in state_dict:
+            rng_states['torch_rng_state'] = state_dict.pop('torch_rng_state')
 
         # Load the optimizer state
         super().load_state_dict(state_dict)
+        state_dict.update(rng_states)  # add back
 
         # Restore the RNG state if it exists
-        if rng_state is not None:
-            self.rng.setstate(rng_state)
-            state_dict['rng_state'] = rng_state  # put it back if caller still using state_dict
-        if torch_rng_state is not None:
-            if self.torch_rng is not None:
-                self.torch_rng.set_state(torch_rng_state)
-            state_dict['torch_rng_state'] = torch_rng_state  # put it back if caller still using state_dict
+        if 'rng_state' in rng_states:
+            self.rng.setstate(rng_states['rng_state'])
+        if 'torch_rng_state' in rng_states:
+            self.torch_rng.set_state(rng_states['torch_rng_state'])
 
     def __setstate__(self, state):
         super().__setstate__(state)
@@ -208,13 +210,16 @@ class Kron(torch.optim.Optimizer):
 
                 grad = p.grad
                 state = self.state[p]
+                if group['flatten_dim']:
+                    grad = grad.view(grad.size(0), -1)
 
                 if len(state) == 0:
                     state["step"] = 0
                     state["update_counter"] = 0
-                    state["momentum_buffer"] = torch.zeros_like(p, dtype=mu_dtype or p.dtype)
+                    state["momentum_buffer"] = torch.zeros_like(grad, dtype=mu_dtype or grad.dtype)
+                    # init Q and einsum expressions on first step
                     state["Q"], exprs = _init_Q_exprs(
-                        p,
+                        grad,
                         group["precond_init_scale"],
                         group["max_size_triangular"],
                         group["min_ndim_triangular"],
@@ -234,8 +239,9 @@ class Kron(torch.optim.Optimizer):
                     total_precond_size += precond_size
                     total_precond_mb += precond_mb
                 elif p not in self._param_exprs:
+                    # init only the einsum expressions, called after state load, Q are loaded from state_dict
                     exprs = _init_Q_exprs(
-                        p,
+                        grad,
                         group["precond_init_scale"],
                         group["max_size_triangular"],
                         group["min_ndim_triangular"],
@@ -245,6 +251,7 @@ class Kron(torch.optim.Optimizer):
                     )
                     self._param_exprs[p] = exprs
                 else:
+                    # retrieve cached expressions
                     exprs = self._param_exprs[p]
 
                 # update preconditioners all together deterministically
@@ -315,6 +322,8 @@ class Kron(torch.optim.Optimizer):
 
                 # RMS of pre_grad should be 1.0, so let's cap at 1.1
                 pre_grad.mul_(torch.clamp(1.1 / (pre_grad.square().mean().sqrt_() + 1e-8), max=1.0))
+                if group['flatten_dim']:
+                    pre_grad = pre_grad.view(p.shape)
 
                 # Apply weight decay
                 if group["weight_decay"] != 0:
@@ -369,9 +378,10 @@ def _init_Q_exprs(
             dim_diag = [False for _ in shape]
             dim_diag[rev_sorted_dims[0]] = True
         elif memory_save_mode == "smart_one_diag":
-            dim_diag = [False for _ in shape]
+            # addition proposed by Lucas Nestler
             rev_sorted_dims = np.argsort(shape)[::-1]
             sorted_shape = sorted(shape)
+            dim_diag = [False for _ in shape]
             if len(shape) >= 2 and sorted_shape[-1] > sorted_shape[-2]:
                 dim_diag[rev_sorted_dims[0]] = True
         elif memory_save_mode == "all_diag":