feat: auto fit tensors across devices to guarantee optimal load (#1736)

docs/backend.md

@@ -115,6 +115,33 @@ Direct ("immediately") LoRA application cannot patch row-split tensors; with
 explicit `--lora-apply-mode immediately` skips the split tensors with a
 warning.
 
+## Automatic placement (`--auto-fit`)
+
+`--auto-fit` derives the `diffusion` / `te` / `vae` placements from the model
+metadata and the per-device memory budgets, then feeds them into the same
+backend assignment mechanism described above (the chosen specs are printed).
+`--backend` and `--params-backend` are ignored while auto-fit is enabled.
+
+```shell
+sd-cli -m model.safetensors -p "a cat" --auto-fit
+sd-cli -m model.safetensors -p "a cat" --auto-fit --max-vram cuda0=8,cuda1=14
+sd-cli -m model.safetensors -p "a cat" --auto-fit --split-mode row
+```
+
+Budgets reuse `--max-vram`: a positive per-device value caps what auto-fit
+plans with on that device, a negative value means "free memory minus that many
+GiB", and with no budget set each device's free memory minus a 512 MiB margin
+is used. (The same values still drive graph-cut segmented execution for
+modules that end up on a single device.)
+
+When everything fits resident, components are simply spread across the
+available GPUs. When it does not, auto-fit switches to time-share mode: the
+heavy components get `disk` params residency (loaded for their phase, freed
+after), and a component too large for any single device is split across all
+GPUs with the layer/row split mechanism (`--split-mode` selects which, layer
+by default). Components that fit nowhere fall back to the CPU. If a VAE decode
+still runs out of memory, tiling is enabled and the decode retried once.
+
 ## Modules
 
 | Module | Purpose | Accepted names |

examples/common/common.cpp

@@ -508,6 +508,12 @@ ArgOptions SDContextParams::get_options() {
          "--eager-load",
          "load all params into the params backend at model-load time instead of lazily on first use (defaults to false)",
          true, &eager_load},
+        {"",
+         "--auto-fit",
+         "pick the diffusion/te/vae device placements automatically from the model size and the per-device "
+         "memory budgets (--max-vram; defaults to free memory minus a small margin). Overrides --backend and "
+         "--params-backend; may split modules across GPUs (--split-mode still selects layer or row)",
+         true, &auto_fit},
         {"",
          "--force-sdxl-vae-conv-scale",
          "force use of conv scale on sdxl vae",
@@ -838,6 +844,7 @@ std::string SDContextParams::to_string() const {
         << "  backend: \"" << backend << "\",\n"
         << "  params_backend: \"" << params_backend << "\",\n"
         << "  split_mode: \"" << split_mode << "\",\n"
+        << "  auto_fit: " << (auto_fit ? "true" : "false") << ",\n"
         << "  enable_mmap: " << (enable_mmap ? "true" : "false") << ",\n"
         << "  control_net_cpu: " << (control_net_cpu ? "true" : "false") << ",\n"
         << "  clip_on_cpu: " << (clip_on_cpu ? "true" : "false") << ",\n"
@@ -919,6 +926,7 @@ sd_ctx_params_t SDContextParams::to_sd_ctx_params_t(bool taesd_preview) {
     sd_ctx_params.backend                         = effective_backend.c_str();
     sd_ctx_params.params_backend                  = effective_params_backend.c_str();
     sd_ctx_params.split_mode                      = split_mode.c_str();
+    sd_ctx_params.auto_fit                        = auto_fit;
     sd_ctx_params.rpc_servers                     = rpc_servers.c_str();
     return sd_ctx_params;
 }

examples/common/common.h

@@ -152,6 +152,7 @@ struct SDContextParams {
     std::string backend;
     std::string params_backend;
     std::string split_mode;
+    bool auto_fit = false;
     std::string rpc_servers;
     std::string effective_backend;
     std::string effective_params_backend;

include/stable-diffusion.h

@@ -228,6 +228,7 @@ typedef struct {
     const char* backend;
     const char* params_backend;
     const char* split_mode;  // weight distribution for multi-device modules: layer (default) or row, or per-module assignments e.g. "diffusion=row"
+    bool auto_fit;
     const char* rpc_servers;
 } sd_ctx_params_t;
 

src/core/backend_fit.cpp

@@ -0,0 +1,390 @@
+#include "backend_fit.h"
+
+#include <algorithm>
+#include <cctype>
+#include <cstdint>
+#include <utility>
+#include <vector>
+
+#include "core/ggml_extend_backend.h"
+#include "core/util.h"
+#include "ggml-backend.h"
+
+namespace sd::backend_fit {
+    namespace {
+
+        constexpr int64_t MiB = 1024ll * 1024;
+
+        enum class ComponentKind {
+            DIT         = 0,
+            VAE         = 1,
+            CONDITIONER = 2,
+        };
+
+        struct Component {
+            ComponentKind kind;
+            const char* name;
+            int64_t params_bytes  = 0;
+            int64_t reserve_bytes = 0;
+            bool splittable       = false;
+        };
+
+        struct Device {
+            ggml_backend_dev_t dev = nullptr;
+            std::string name;
+            std::string description;
+            int64_t free_bytes   = 0;
+            int64_t total_bytes  = 0;
+            int64_t budget_bytes = 0;
+        };
+
+        struct Decision {
+            ComponentKind kind;
+            bool on_cpu = false;
+            std::vector<size_t> device_idxs;
+        };
+
+        struct Plan {
+            bool valid      = false;
+            bool time_share = false;
+            std::vector<Decision> decisions;
+        };
+
+        bool classify_tensor(const std::string& name, ComponentKind& out) {
+            auto contains = [&](const char* s) { return name.find(s) != std::string::npos; };
+
+            if (contains("model.diffusion_model.") || contains("unet.")) {
+                out = ComponentKind::DIT;
+                return true;
+            }
+            if (contains("first_stage_model.") ||
+                name.rfind("vae.", 0) == 0 ||
+                name.rfind("tae.", 0) == 0) {
+                out = ComponentKind::VAE;
+                return true;
+            }
+            if (contains("text_encoders") ||
+                contains("cond_stage_model") ||
+                contains("te.text_model.") ||
+                contains("conditioner") ||
+                name.rfind("text_encoder.", 0) == 0 ||
+                name.rfind("text_embedding_projection.", 0) == 0 ||
+                contains(".aggregate_embed.")) {
+                out = ComponentKind::CONDITIONER;
+                return true;
+            }
+            return false;
+        }
+
+        std::vector<Component> estimate_components(ModelLoader& loader, ggml_type override_wtype) {
+            const auto& storage = loader.get_tensor_storage_map();
+
+            int64_t bytes[3] = {0, 0, 0};
+            for (const auto& [name, ts_const] : storage) {
+                TensorStorage ts = ts_const;
+                if (is_unused_tensor(ts.name)) {
+                    continue;
+                }
+                ComponentKind kind;
+                if (!classify_tensor(ts.name, kind)) {
+                    continue;
+                }
+                if (override_wtype != GGML_TYPE_COUNT &&
+                    loader.tensor_should_be_converted(ts, override_wtype)) {
+                    ts.type = override_wtype;
+                } else if (ts.expected_type != GGML_TYPE_COUNT && ts.expected_type != ts.type) {
+                    ts.type = ts.expected_type;
+                }
+                bytes[int(kind)] += (int64_t)ts.nbytes() + 64;
+            }
+
+            std::vector<Component> out;
+            out.push_back({ComponentKind::DIT, "DiT", bytes[int(ComponentKind::DIT)], 2048 * MiB, true});
+            out.push_back({ComponentKind::VAE, "VAE", bytes[int(ComponentKind::VAE)], 1024 * MiB, false});
+            out.push_back({ComponentKind::CONDITIONER, "Conditioner", bytes[int(ComponentKind::CONDITIONER)], 2048 * MiB, true});
+            return out;
+        }
+
+        std::vector<Device> enumerate_gpu_devices(const sd::ggml_graph_cut::MaxVramAssignment& budgets) {
+            std::vector<Device> out;
+            for (size_t i = 0; i < ggml_backend_dev_count(); i++) {
+                ggml_backend_dev_t dev = ggml_backend_dev_get(i);
+                if (ggml_backend_dev_type(dev) != GGML_BACKEND_DEVICE_TYPE_GPU) {
+                    continue;
+                }
+                Device d;
+                d.dev             = dev;
+                d.name            = ggml_backend_dev_name(dev);
+                d.description     = ggml_backend_dev_description(dev);
+                size_t free_bytes = 0, total_bytes = 0;
+                ggml_backend_dev_memory(dev, &free_bytes, &total_bytes);
+                d.free_bytes  = (int64_t)free_bytes;
+                d.total_bytes = (int64_t)total_bytes;
+
+                std::string budget_key = d.name;
+                std::transform(budget_key.begin(), budget_key.end(), budget_key.begin(),
+                               [](unsigned char c) { return (char)std::tolower(c); });
+                float gib = budgets.default_gib;
+                auto it   = budgets.backend_gib.find(budget_key);
+                if (it != budgets.backend_gib.end()) {
+                    gib = it->second;
+                }
+                if (gib > 0.f) {
+                    d.budget_bytes = std::min<int64_t>((int64_t)(gib * 1024.0 * 1024.0 * 1024.0), d.free_bytes);
+                } else if (gib < 0.f) {
+                    d.budget_bytes = d.free_bytes + (int64_t)(gib * 1024.0 * 1024.0 * 1024.0);
+                } else {
+                    d.budget_bytes = d.free_bytes - 512 * MiB;
+                }
+                d.budget_bytes = std::max<int64_t>(d.budget_bytes, 0);
+                out.push_back(d);
+            }
+            return out;
+        }
+
+        Plan compute_plan(const std::vector<Component>& components, const std::vector<Device>& devices) {
+            Plan plan;
+            if (devices.empty()) {
+                return plan;
+            }
+
+            std::vector<size_t> order(components.size());
+            for (size_t i = 0; i < order.size(); i++) {
+                order[i] = i;
+            }
+            std::sort(order.begin(), order.end(), [&](size_t a, size_t b) {
+                return components[a].params_bytes > components[b].params_bytes;
+            });
+
+            {
+                std::vector<int64_t> params_sum(devices.size(), 0);
+                std::vector<int64_t> max_reserve(devices.size(), 0);
+                std::vector<Decision> decisions(components.size());
+                bool ok = true;
+                for (size_t ci : order) {
+                    const Component& comp = components[ci];
+                    decisions[ci].kind    = comp.kind;
+                    if (comp.params_bytes == 0) {
+                        continue;
+                    }
+                    int best = -1;
+                    for (size_t di = 0; di < devices.size(); di++) {
+                        int64_t need = params_sum[di] + comp.params_bytes + std::max(max_reserve[di], comp.reserve_bytes);
+                        if (need <= devices[di].budget_bytes &&
+                            (best < 0 || devices[di].budget_bytes - params_sum[di] > devices[best].budget_bytes - params_sum[best])) {
+                            best = (int)di;
+                        }
+                    }
+                    if (best < 0) {
+                        ok = false;
+                        break;
+                    }
+                    params_sum[best] += comp.params_bytes;
+                    max_reserve[best] = std::max(max_reserve[best], comp.reserve_bytes);
+                    decisions[ci].device_idxs.push_back((size_t)best);
+                }
+                if (ok) {
+                    plan.valid      = true;
+                    plan.time_share = false;
+                    plan.decisions  = std::move(decisions);
+                    return plan;
+                }
+            }
+
+            plan.decisions.assign(components.size(), {});
+            for (size_t ci : order) {
+                const Component& comp = components[ci];
+                Decision& decision    = plan.decisions[ci];
+                decision.kind         = comp.kind;
+                if (comp.params_bytes == 0) {
+                    continue;
+                }
+                int best = -1;
+                for (size_t di = 0; di < devices.size(); di++) {
+                    if (comp.params_bytes + comp.reserve_bytes <= devices[di].budget_bytes &&
+                        (best < 0 || devices[di].budget_bytes > devices[best].budget_bytes)) {
+                        best = (int)di;
+                    }
+                }
+                if (best >= 0) {
+                    decision.device_idxs.push_back((size_t)best);
+                    continue;
+                }
+                if (comp.splittable && devices.size() > 1) {
+                    int64_t capacity = 0;
+                    for (const Device& d : devices) {
+                        capacity += std::max<int64_t>(d.budget_bytes - comp.reserve_bytes, 0);
+                    }
+                    if (comp.params_bytes <= capacity) {
+                        std::vector<size_t> idxs(devices.size());
+                        for (size_t i = 0; i < idxs.size(); i++) {
+                            idxs[i] = i;
+                        }
+                        std::sort(idxs.begin(), idxs.end(), [&](size_t a, size_t b) {
+                            return devices[a].budget_bytes > devices[b].budget_bytes;
+                        });
+                        decision.device_idxs = std::move(idxs);
+                        continue;
+                    }
+                }
+                decision.on_cpu = true;
+            }
+            plan.valid      = true;
+            plan.time_share = true;
+            return plan;
+        }
+
+        void print_plan(const Plan& plan,
+                        const std::vector<Component>& components,
+                        const std::vector<Device>& devices) {
+            LOG_INFO("auto-fit plan%s:", plan.time_share ? " (time-share: params load per phase and free after)" : "");
+            LOG_INFO("  devices:");
+            for (const Device& d : devices) {
+                LOG_INFO("    %-12s %-32s free %6lld MiB, budget %6lld MiB",
+                         d.name.c_str(), d.description.c_str(),
+                         (long long)(d.free_bytes / MiB), (long long)(d.budget_bytes / MiB));
+            }
+            LOG_INFO("  components:");
+            for (size_t ci = 0; ci < components.size(); ci++) {
+                const Component& comp    = components[ci];
+                const Decision& decision = plan.decisions[ci];
+                std::string target;
+                if (comp.params_bytes == 0) {
+                    target = "(not present)";
+                } else if (decision.on_cpu) {
+                    target = "CPU";
+                } else {
+                    for (size_t k = 0; k < decision.device_idxs.size(); k++) {
+                        if (k > 0) {
+                            target += " & ";
+                        }
+                        target += devices[decision.device_idxs[k]].name;
+                    }
+                    if (decision.device_idxs.size() > 1) {
+                        target += " (split)";
+                    }
+                }
+                LOG_INFO("    %-12s params %6lld MiB, compute reserve %5lld MiB -> %s",
+                         comp.name,
+                         (long long)(comp.params_bytes / MiB),
+                         (long long)(comp.reserve_bytes / MiB),
+                         target.c_str());
+            }
+        }
+
+        void append_assignment(std::string& spec, const char* key, const std::string& value) {
+            if (!spec.empty()) {
+                spec += ",";
+            }
+            spec += key;
+            spec += "=";
+            spec += value;
+        }
+
+        void append_component_decision(const std::vector<Component>& components,
+                                       const std::vector<Device>& devices,
+                                       const Plan& plan,
+                                       ComponentKind kind,
+                                       const char* module_key,
+                                       std::string& runtime_spec,
+                                       std::string& params_spec) {
+            for (size_t ci = 0; ci < components.size(); ci++) {
+                if (components[ci].kind != kind || components[ci].params_bytes == 0) {
+                    continue;
+                }
+                const Decision& decision = plan.decisions[ci];
+                if (decision.on_cpu) {
+                    append_assignment(runtime_spec, module_key, "cpu");
+                    return;
+                }
+                if (decision.device_idxs.empty()) {
+                    return;
+                }
+                std::string device_list;
+                for (size_t k = 0; k < decision.device_idxs.size(); k++) {
+                    if (k > 0) {
+                        device_list += "&";
+                    }
+                    device_list += devices[decision.device_idxs[k]].name;
+                }
+                append_assignment(runtime_spec, module_key, device_list);
+                if (plan.time_share) {
+                    append_assignment(params_spec, module_key, "disk");
+                }
+                return;
+            }
+        }
+
+    }  // namespace
+
+    bool derive_backend_specs(ModelLoader& loader,
+                              ggml_type override_wtype,
+                              sd::ggml_graph_cut::MaxVramAssignment& budgets,
+                              std::string& runtime_spec,
+                              std::string& params_spec) {
+        if (!runtime_spec.empty() || !params_spec.empty()) {
+            LOG_WARN("--auto-fit is enabled; ignoring --backend / --params-backend");
+        }
+
+        {
+            std::string error;
+            if (!budgets.canonicalize_backend_keys(&error)) {
+                LOG_ERROR("%s", error.c_str());
+                return false;
+            }
+        }
+
+        auto components = estimate_components(loader, override_wtype);
+        auto devices    = enumerate_gpu_devices(budgets);
+        auto plan       = compute_plan(components, devices);
+        if (!plan.valid) {
+            LOG_WARN("auto-fit: no usable GPU devices; using the default backend");
+            runtime_spec.clear();
+            params_spec.clear();
+            return true;
+        }
+
+        print_plan(plan, components, devices);
+
+        std::string derived_runtime_spec;
+        std::string derived_params_spec;
+        append_component_decision(components, devices, plan, ComponentKind::DIT, "diffusion", derived_runtime_spec, derived_params_spec);
+        append_component_decision(components, devices, plan, ComponentKind::CONDITIONER, "te", derived_runtime_spec, derived_params_spec);
+        append_component_decision(components, devices, plan, ComponentKind::VAE, "vae", derived_runtime_spec, derived_params_spec);
+
+        runtime_spec = std::move(derived_runtime_spec);
+        params_spec  = std::move(derived_params_spec);
+
+        LOG_INFO("auto-fit: --backend \"%s\"%s%s%s",
+                 runtime_spec.empty() ? "(default)" : runtime_spec.c_str(),
+                 params_spec.empty() ? "" : " --params-backend \"",
+                 params_spec.c_str(),
+                 params_spec.empty() ? "" : "\"");
+        return true;
+    }
+
+    bool prepare_vae_decode_retry_tiling(sd_tiling_params_t& tiling_params, bool prefer_temporal_tiling) {
+        if (prefer_temporal_tiling) {
+            if (tiling_params.temporal_tiling) {
+                return false;
+            }
+            tiling_params.temporal_tiling = true;
+        } else {
+            if (tiling_params.enabled) {
+                return false;
+            }
+            tiling_params.enabled = true;
+            if (tiling_params.tile_size_x <= 0) {
+                tiling_params.tile_size_x = 256;
+            }
+            if (tiling_params.tile_size_y <= 0) {
+                tiling_params.tile_size_y = 256;
+            }
+        }
+
+        LOG_WARN("auto-fit: VAE decode failed (likely out of memory); retrying with %s tiling",
+                 tiling_params.temporal_tiling ? "temporal" : "spatial");
+        return true;
+    }
+
+}  // namespace sd::backend_fit

src/core/backend_fit.h

@@ -0,0 +1,23 @@
+#ifndef __SD_BACKEND_FIT_H__
+#define __SD_BACKEND_FIT_H__
+
+#include <string>
+
+#include "core/ggml_graph_cut.h"
+#include "model_loader.h"
+#include "stable-diffusion.h"
+
+namespace sd::backend_fit {
+
+    bool derive_backend_specs(ModelLoader& loader,
+                              ggml_type override_wtype,
+                              sd::ggml_graph_cut::MaxVramAssignment& budgets,
+                              std::string& runtime_spec,
+                              std::string& params_spec);
+
+    bool prepare_vae_decode_retry_tiling(sd_tiling_params_t& tiling_params,
+                                         bool prefer_temporal_tiling);
+
+}  // namespace sd::backend_fit
+
+#endif  // __SD_BACKEND_FIT_H__

src/model_loader.h

@@ -27,6 +27,8 @@ struct MmapTensorStore {
     std::shared_ptr<struct ggml_backend_buffer> mmbuffer;
 };
 
+bool is_unused_tensor(const std::string& name);
+
 class ModelLoader {
 protected:
     SDVersion version_ = VERSION_COUNT;

src/stable-diffusion.cpp

@@ -20,6 +20,7 @@
 #include "stable-diffusion.h"
 
 #include "conditioning/conditioner.hpp"
+#include "core/backend_fit.h"
 #include "extensions/generation_extension.h"
 #include "model/adapter/lora.hpp"
 #include "model/diffusion/anima.hpp"
@@ -219,6 +220,7 @@ public:
     std::string backend_spec;
     std::string params_backend_spec;
     std::string split_mode_spec;
+    bool auto_fit_enabled = false;
 
     bool is_using_v_parameterization     = false;
     bool is_using_edm_v_parameterization = false;
@@ -586,6 +588,7 @@ public:
         backend_spec        = SAFE_STR(sd_ctx_params->backend);
         params_backend_spec = SAFE_STR(sd_ctx_params->params_backend);
         split_mode_spec     = SAFE_STR(sd_ctx_params->split_mode);
+        auto_fit_enabled    = sd_ctx_params->auto_fit;
         max_vram_assignment.reset(0.f);
         {
             std::string error;
@@ -611,21 +614,6 @@ public:
 
         ggml_log_set(ggml_log_callback_default, nullptr);
 
-        if (!init_backend()) {
-            return false;
-        }
-        {
-            std::string error;
-            if (!max_vram_assignment.canonicalize_backend_keys(&error)) {
-                LOG_ERROR("%s", error.c_str());
-                return false;
-            }
-        }
-        if (stream_layers && !backend_manager.params_backend_is_cpu(SDBackendModule::DIFFUSION)) {
-            LOG_WARN("--stream-layers has no effect unless diffusion params backend is cpu; ignoring");
-            stream_layers = false;
-        }
-
         model_manager = std::make_shared<ModelManager>();
         model_manager->set_n_threads(n_threads);
         model_manager->set_enable_mmap(enable_mmap);
@@ -773,6 +761,31 @@ public:
             model_loader.set_wtype_override(wtype, tensor_type_rules);
         }
 
+        if (auto_fit_enabled) {
+            if (!sd::backend_fit::derive_backend_specs(model_loader,
+                                                       wtype,
+                                                       max_vram_assignment,
+                                                       backend_spec,
+                                                       params_backend_spec)) {
+                return false;
+            }
+        }
+
+        if (!init_backend()) {
+            return false;
+        }
+        {
+            std::string error;
+            if (!max_vram_assignment.canonicalize_backend_keys(&error)) {
+                LOG_ERROR("%s", error.c_str());
+                return false;
+            }
+        }
+        if (stream_layers && !backend_manager.params_backend_is_cpu(SDBackendModule::DIFFUSION)) {
+            LOG_WARN("--stream-layers has no effect unless diffusion params backend is cpu; ignoring");
+            stream_layers = false;
+        }
+
         std::map<ggml_type, uint32_t> wtype_stat                 = model_loader.get_wtype_stat();
         std::map<ggml_type, uint32_t> conditioner_wtype_stat     = model_loader.get_conditioner_wtype_stat();
         std::map<ggml_type, uint32_t> diffusion_model_wtype_stat = model_loader.get_diffusion_model_wtype_stat();
@@ -2689,7 +2702,16 @@ public:
         }
         auto latents = first_stage_model->diffusion_to_vae_latents(x);
         first_stage_model->set_temporal_tiling_enabled(vae_tiling_params.temporal_tiling);
-        return first_stage_model->decode(n_threads, latents, vae_tiling_params, decode_video, circular_x, circular_y);
+        auto decoded = first_stage_model->decode(n_threads, latents, vae_tiling_params, decode_video, circular_x, circular_y);
+        if (decoded.empty() && auto_fit_enabled) {
+            bool prefer_temporal_tiling = decode_video && std::dynamic_pointer_cast<LTXVideoVAE>(first_stage_model) != nullptr;
+            if (sd::backend_fit::prepare_vae_decode_retry_tiling(vae_tiling_params, prefer_temporal_tiling)) {
+                first_stage_model->free_compute_buffer();
+                first_stage_model->set_temporal_tiling_enabled(vae_tiling_params.temporal_tiling);
+                decoded = first_stage_model->decode(n_threads, latents, vae_tiling_params, decode_video, circular_x, circular_y);
+            }
+        }
+        return decoded;
     }
 
     sd::Tensor<float> normalize_ltx_video_latents(const sd::Tensor<float>& x) {
@@ -3046,6 +3068,7 @@ void sd_ctx_params_init(sd_ctx_params_t* sd_ctx_params) {
     sd_ctx_params->backend              = nullptr;
     sd_ctx_params->params_backend       = nullptr;
     sd_ctx_params->split_mode           = nullptr;
+    sd_ctx_params->auto_fit             = false;
     sd_ctx_params->rpc_servers          = nullptr;
     sd_ctx_params->pulid_weights_path   = nullptr;
 }
@@ -3086,6 +3109,7 @@ char* sd_ctx_params_to_str(const sd_ctx_params_t* sd_ctx_params) {
              "backend: %s\n"
              "params_backend: %s\n"
              "split_mode: %s\n"
+             "auto_fit: %s\n"
              "flash_attn: %s\n"
              "diffusion_flash_attn: %s\n"
              "circular_x: %s\n"
@@ -3123,6 +3147,7 @@ char* sd_ctx_params_to_str(const sd_ctx_params_t* sd_ctx_params) {
              SAFE_STR(sd_ctx_params->backend),
              SAFE_STR(sd_ctx_params->params_backend),
              SAFE_STR(sd_ctx_params->split_mode),
+             BOOL_STR(sd_ctx_params->auto_fit),
              BOOL_STR(sd_ctx_params->flash_attn),
              BOOL_STR(sd_ctx_params->diffusion_flash_attn),
              BOOL_STR(sd_ctx_params->circular_x),