Fix loras having a weak effect when applied on fp8.

comfy/float.py

@@ -0,0 +1,51 @@
+import torch
+
+#Not 100% sure about this
+def manual_stochastic_round_to_float8(x, dtype):
+    if dtype == torch.float8_e4m3fn:
+        EXPONENT_BITS, MANTISSA_BITS, EXPONENT_BIAS = 4, 3, 7
+    elif dtype == torch.float8_e5m2:
+        EXPONENT_BITS, MANTISSA_BITS, EXPONENT_BIAS = 5, 2, 15
+    else:
+        raise ValueError("Unsupported dtype")
+
+    sign = torch.sign(x)
+    abs_x = x.abs()
+
+    # Combine exponent calculation and clamping
+    exponent = torch.clamp(
+        torch.floor(torch.log2(abs_x)).to(torch.int32) + EXPONENT_BIAS,
+        0, 2**EXPONENT_BITS - 1
+    )
+
+    # Combine mantissa calculation and rounding
+    mantissa = abs_x / (2.0 ** (exponent - EXPONENT_BIAS)) - 1.0
+    mantissa_scaled = mantissa * (2**MANTISSA_BITS)
+    mantissa_floor = mantissa_scaled.floor()
+    mantissa = torch.where(
+        torch.rand_like(mantissa_scaled) < (mantissa_scaled - mantissa_floor),
+        (mantissa_floor + 1) / (2**MANTISSA_BITS),
+        mantissa_floor / (2**MANTISSA_BITS)
+    )
+
+    # Combine final result calculation
+    result = sign * (2.0 ** (exponent - EXPONENT_BIAS)) * (1.0 + mantissa)
+
+    # Handle zero case
+    result = torch.where(abs_x == 0, torch.zeros_like(result), result)
+
+    return result.to(dtype=dtype)
+
+
+
+def stochastic_rounding(value, dtype):
+    if dtype == torch.float32:
+        return value.to(dtype=torch.float32)
+    if dtype == torch.float16:
+        return value.to(dtype=torch.float16)
+    if dtype == torch.bfloat16:
+        return value.to(dtype=torch.bfloat16)
+    if dtype == torch.float8_e4m3fn or dtype == torch.float8_e5m2:
+        return manual_stochastic_round_to_float8(value, dtype)
+
+    return value.to(dtype=dtype)

comfy/model_patcher.py

@@ -22,8 +22,10 @@ import inspect
 import logging
 import uuid
 import collections
+import math
 
 import comfy.utils
+import comfy.float
 import comfy.model_management
 from comfy.types import UnetWrapperFunction
 
@@ -327,7 +329,8 @@ class ModelPatcher:
             temp_weight = comfy.model_management.cast_to_device(weight, device_to, torch.float32, copy=True)
         else:
             temp_weight = weight.to(torch.float32, copy=True)
-        out_weight = self.calculate_weight(self.patches[key], temp_weight, key).to(weight.dtype)
+        out_weight = self.calculate_weight(self.patches[key], temp_weight, key)
+        out_weight = comfy.float.stochastic_rounding(out_weight, weight.dtype)
         if inplace_update:
             comfy.utils.copy_to_param(self.model, key, out_weight)
         else:
@@ -341,12 +344,16 @@ class ModelPatcher:
 
         if patch_weights:
             model_sd = self.model_state_dict()
+            keys_sort = []
             for key in self.patches:
                 if key not in model_sd:
                     logging.warning("could not patch. key doesn't exist in model: {}".format(key))
                     continue
+                keys_sort.append((math.prod(model_sd[key].shape), key))
 
-                self.patch_weight_to_device(key, device_to)
+            keys_sort.sort(reverse=True)
+            for ks in keys_sort:
+                self.patch_weight_to_device(ks[1], device_to)
 
             if device_to is not None:
                 self.model.to(device_to)
@@ -359,6 +366,7 @@ class ModelPatcher:
         mem_counter = 0
         patch_counter = 0
         lowvram_counter = 0
+        load_completely = []
         for n, m in self.model.named_modules():
             lowvram_weight = False
 
@@ -395,20 +403,28 @@ class ModelPatcher:
                         wipe_lowvram_weight(m)
 
                 if hasattr(m, "weight"):
-                    mem_counter += comfy.model_management.module_size(m)
-                    param = list(m.parameters())
-                    if len(param) > 0:
-                        weight = param[0]
-                        if weight.device == device_to:
-                            continue
-
-                    weight_to = None
-                    if full_load:#TODO
-                        weight_to = device_to
-                    self.patch_weight_to_device(weight_key, device_to=weight_to) #TODO: speed this up without OOM
-                    self.patch_weight_to_device(bias_key, device_to=weight_to)
-                    m.to(device_to)
-                    logging.debug("lowvram: loaded module regularly {} {}".format(n, m))
+                    mem_used = comfy.model_management.module_size(m)
+                    mem_counter += mem_used
+                    load_completely.append((mem_used, n, m))
+
+        load_completely.sort(reverse=True)
+        for x in load_completely:
+            n = x[1]
+            m = x[2]
+            weight_key = "{}.weight".format(n)
+            bias_key = "{}.bias".format(n)
+            param = list(m.parameters())
+            if len(param) > 0:
+                weight = param[0]
+                if weight.device == device_to:
+                    continue
+
+            self.patch_weight_to_device(weight_key, device_to=device_to)
+            self.patch_weight_to_device(bias_key, device_to=device_to)
+            logging.debug("lowvram: loaded module regularly {} {}".format(n, m))
+
+        for x in load_completely:
+            x[2].to(device_to)
 
         if lowvram_counter > 0:
             logging.info("loaded partially {} {} {}".format(lowvram_model_memory / (1024 * 1024), mem_counter / (1024 * 1024), patch_counter))