Revert "llama : Async DirectIO model loading on Linux (ggml-org#18012)"

LostRuins · LostRuins · commit a45fc5ee8820 · 2025-12-19T19:06:30.000+08:00
This reverts commit 4d4f4ca.
diff --git a/src/llama-mmap.cpp b/src/llama-mmap.cpp
@@ -13,10 +13,9 @@
 #ifdef __has_include
     #if __has_include(<unistd.h>)
         #include <unistd.h>
-        #include <fcntl.h>
-        #include <sys/stat.h>
         #if defined(_POSIX_MAPPED_FILES)
             #include <sys/mman.h>
+            #include <fcntl.h>
         #endif
         #if defined(_POSIX_MEMLOCK_RANGE)
             #include <sys/resource.h>
@@ -75,7 +74,7 @@ struct llama_file::impl {
         return ret;
     }
 
-    impl(const char * fname, const char * mode, [[maybe_unused]] const bool use_direct_io = false) {
+    impl(const char * fname, const char * mode) {
         fp = ggml_fopen(fname, mode);
         if (fp == NULL) {
             throw std::runtime_error(format("failed to open %s: %s", fname, strerror(errno)));
@@ -154,40 +153,13 @@ struct llama_file::impl {
         write_raw(&val, sizeof(val));
     }
 
-    void read_aligned_chunk(size_t offset, void * dest, size_t size) const {
-        throw std::runtime_error("DirectIO is not implemented on Windows.");
-    }
-
     ~impl() {
         if (fp) {
             std::fclose(fp);
         }
     }
 #else
-    impl(const char * fname, const char * mode, [[maybe_unused]] const bool use_direct_io = false) {
-#ifdef __linux__
-        // Try unbuffered I/O for read only
-        if (use_direct_io && std::strcmp(mode, "rb") == 0) {
-            fd = open(fname, O_RDONLY | O_DIRECT);
-
-            if (fd != -1) {
-                struct stat file_stats{};
-                fstat(fd, &file_stats);
-
-                size = file_stats.st_size;
-                alignment = file_stats.st_blksize;
-
-                off_t ret = lseek(fd, 0, SEEK_SET);
-                if (ret == -1) {
-                    throw std::runtime_error(format("seek error: %s", strerror(errno)));
-                }
-                return;
-            }
-
-            LLAMA_LOG_WARN("Failed to open model %s with error: %s. Falling back to buffered I/O",
-                fname, strerror(errno));
-        }
-#endif
+    impl(const char * fname, const char * mode) {
         fp = ggml_fopen(fname, mode);
         if (fp == NULL) {
             throw std::runtime_error(format("failed to open %s: %s", fname, strerror(errno)));
@@ -198,30 +170,27 @@ struct llama_file::impl {
     }
 
     size_t tell() const {
-        if (fd == -1) {
-            long ret = std::ftell(fp);
-            if (ret == -1) {
-                throw std::runtime_error(format("ftell error: %s", strerror(errno)));
-            }
-
-            return (size_t) ret;
+// TODO: this ifdef is never true?
+#ifdef _WIN32
+        __int64 ret = _ftelli64(fp);
+#else
+        long ret = std::ftell(fp);
+#endif
+        if (ret == -1) {
+            throw std::runtime_error(format("ftell error: %s", strerror(errno)));
         }
 
-        off_t pos = lseek(fd, 0, SEEK_CUR);
-        if (pos == -1) {
-            throw std::runtime_error(format("lseek error: %s", strerror(errno)));
-        }
-        return (size_t) pos;
+        return (size_t) ret;
     }
 
     void seek(size_t offset, int whence) const {
-        off_t ret = 0;
-        if (fd == -1) {
-            ret = std::fseek(fp, (long) offset, whence);
-        } else {
-            ret = lseek(fd, offset, whence);
-        }
-        if (ret == -1) {
+// TODO: this ifdef is never true?
+#ifdef _WIN32
+        int ret = _fseeki64(fp, (__int64) offset, whence);
+#else
+        int ret = std::fseek(fp, (long) offset, whence);
+#endif
+        if (ret != 0) {
             throw std::runtime_error(format("seek error: %s", strerror(errno)));
         }
     }
@@ -231,55 +200,13 @@ struct llama_file::impl {
             return;
         }
         errno = 0;
-        if (fd == -1) {
-            std::size_t ret = std::fread(ptr, len, 1, fp);
-            if (ferror(fp)) {
-                throw std::runtime_error(format("read error: %s", strerror(errno)));
-            }
-            if (ret != 1) {
-                throw std::runtime_error("unexpectedly reached end of file");
-            }
-        } else {
-            bool successful = false;
-            while (!successful) {
-                off_t ret = read(fd, ptr, len);
-
-                if (ret == -1) {
-                    if (errno == EINTR) {
-                        continue;  // Interrupted by signal, retry
-                    }
-                    throw std::runtime_error(format("read error: %s", strerror(errno)));
-                }
-                if (ret == 0) {
-                    throw std::runtime_error("unexpectedly reached end of file");
-                }
-
-                successful = true;
-            }
+        std::size_t ret = std::fread(ptr, len, 1, fp);
+        if (ferror(fp)) {
+            throw std::runtime_error(format("read error: %s", strerror(errno)));
         }
-    }
-
-    void read_aligned_chunk(size_t offset, void * dest, size_t size) const {
-        off_t aligned_offset = offset & ~(alignment - 1);
-        off_t offset_from_alignment = offset - aligned_offset;
-        size_t bytes_to_read = (offset_from_alignment + size + alignment - 1) & ~(alignment - 1);
-
-        void * raw_buffer = nullptr;
-        int ret = posix_memalign(&raw_buffer, alignment, bytes_to_read);
-        if (ret != 0) {
-            throw std::runtime_error(format("posix_memalign failed with error %d", ret));
+        if (ret != 1) {
+            throw std::runtime_error("unexpectedly reached end of file");
         }
-
-        struct aligned_buffer_deleter {
-            void operator()(void * p) const { free(p); }
-        };
-        std::unique_ptr<void, aligned_buffer_deleter> buffer(raw_buffer);
-
-        seek(aligned_offset, SEEK_SET);
-        read_raw(buffer.get(), bytes_to_read);
-
-        uintptr_t actual_data = reinterpret_cast<uintptr_t>(buffer.get()) + offset_from_alignment;
-        memcpy(dest, reinterpret_cast<void *>(actual_data), size);
     }
 
     uint32_t read_u32() const {
@@ -304,43 +231,22 @@ struct llama_file::impl {
     }
 
     ~impl() {
-        if (fd != -1) {
-            close(fd);
-        } else {
+        if (fp) {
             std::fclose(fp);
         }
     }
-    int fd = -1;
 #endif
 
-    void read_raw_at(void * ptr, size_t len, size_t offset) const {
-        if (alignment != 1) {
-            read_aligned_chunk(offset, ptr, len);
-        } else {
-            seek(offset, SEEK_SET);
-            read_raw(ptr, len);
-        }
-    }
-
-    size_t read_alignment() const {
-        return alignment;
-    }
-
-    size_t alignment = 1;
-
-    FILE * fp{};
-    size_t size{};
+    FILE * fp;
+    size_t size;
 };
 
-llama_file::llama_file(const char * fname, const char * mode, const bool use_direct_io) :
-    pimpl(std::make_unique<impl>(fname, mode, use_direct_io)) {}
+llama_file::llama_file(const char * fname, const char * mode) : pimpl(std::make_unique<impl>(fname, mode)) {}
 llama_file::~llama_file() = default;
 
 size_t llama_file::tell() const { return pimpl->tell(); }
 size_t llama_file::size() const { return pimpl->size; }
 
-size_t llama_file::read_alignment() const { return pimpl->read_alignment(); }
-
 int llama_file::file_id() const {
 #ifdef _WIN32
     return _fileno(pimpl->fp);
@@ -355,7 +261,6 @@ int llama_file::file_id() const {
 
 void llama_file::seek(size_t offset, int whence) const { pimpl->seek(offset, whence); }
 void llama_file::read_raw(void * ptr, size_t len) const { pimpl->read_raw(ptr, len); }
-void llama_file::read_raw_at(void * ptr, size_t len, size_t offset) const { pimpl->read_raw_at(ptr, len, offset); }
 
 uint32_t llama_file::read_u32() const { return pimpl->read_u32(); }
 
diff --git a/src/llama-mmap.h b/src/llama-mmap.h
@@ -3,7 +3,6 @@
 #include <cstdint>
 #include <memory>
 #include <vector>
-#include <cstdio>
 
 struct llama_file;
 struct llama_mmap;
@@ -14,7 +13,7 @@ using llama_mmaps  = std::vector<std::unique_ptr<llama_mmap>>;
 using llama_mlocks = std::vector<std::unique_ptr<llama_mlock>>;
 
 struct llama_file {
-    llama_file(const char * fname, const char * mode, bool use_direct_io = false);
+    llama_file(const char * fname, const char * mode);
     ~llama_file();
 
     size_t tell() const;
@@ -25,14 +24,11 @@ struct llama_file {
     void seek(size_t offset, int whence) const;
 
     void read_raw(void * ptr, size_t len) const;
-    void read_raw_at(void * ptr, size_t len, size_t offset) const;
-    void read_aligned_chunk(size_t offset, void * dest, size_t size) const;
     uint32_t read_u32() const;
 
     void write_raw(const void * ptr, size_t len) const;
     void write_u32(uint32_t val) const;
 
-    size_t read_alignment() const;
 private:
     struct impl;
     std::unique_ptr<impl> pimpl;
diff --git a/src/llama-model-loader.cpp b/src/llama-model-loader.cpp
@@ -508,7 +508,7 @@ llama_model_loader::llama_model_loader(
     get_key(llm_kv(LLM_KV_GENERAL_ARCHITECTURE), arch_name, false);
     llm_kv = LLM_KV(llm_arch_from_string(arch_name));
 
-    files.emplace_back(new llama_file(fname.c_str(), "rb", !use_mmap));
+    files.emplace_back(new llama_file(fname.c_str(), "rb"));
     contexts.emplace_back(ctx);
 
     // Save tensors data offset of the main file.
@@ -576,7 +576,7 @@ llama_model_loader::llama_model_loader(
                 }
             }
 
-            files.emplace_back(new llama_file(fname_split, "rb", !use_mmap));
+            files.emplace_back(new llama_file(fname_split, "rb"));
             contexts.emplace_back(ctx);
 
             // Save tensors data offset info of the shard.
@@ -958,15 +958,7 @@ bool llama_model_loader::load_all_data(
     // 4 staging buffers for async uploads, each sized 1MB seems to be a good default for single NVMe drives.
     // NVMe raid configurations might require more / larger buffers.
     constexpr size_t n_buffers = 4;
-
-    size_t alignment = 1;
-    for (const auto & file : files) {
-        alignment = std::max(file->read_alignment(), alignment);
-    }
-
-    // Buffer size: balance between memory usage and I/O efficiency
-    // 64MB works well for NVMe drives
-    const size_t buffer_size = alignment != 1 ? 64 * 1024 * 1024 + 2 * alignment : 1 * 1024 * 1024;
+    constexpr size_t buffer_size = 1 * 1024 * 1024; // 1MB
 
     std::vector<ggml_backend_buffer_t> host_buffers;
     std::vector<ggml_backend_event_t> events;
@@ -1016,7 +1008,6 @@ bool llama_model_loader::load_all_data(
         // If the backend is supported, create pinned memory buffers and events for synchronisation.
         for (size_t idx = 0; idx < n_buffers; ++idx) {
             auto * buf = ggml_backend_buft_alloc_buffer(host_buft, buffer_size);
-
             if (!buf) {
                 LLAMA_LOG_DEBUG("%s: failed to allocate host buffer for async uploads for device %s\n", func,
                     ggml_backend_dev_name(dev));
@@ -1098,9 +1089,9 @@ bool llama_model_loader::load_all_data(
             }
         } else {
             const auto & file = files.at(weight->idx);
-
             if (ggml_backend_buffer_is_host(cur->buffer)) {
-                file->read_raw_at(cur->data, n_size, weight->offs);
+                file->seek(weight->offs, SEEK_SET);
+                file->read_raw(cur->data, n_size);
                 if (check_tensors) {
                     validation_result.emplace_back(std::async(std::launch::async, [cur, n_size] {
                         return std::make_pair(cur, ggml_validate_row_data(cur->type, cur->data, n_size));
@@ -1109,60 +1100,26 @@ bool llama_model_loader::load_all_data(
             } else {
                 // If upload_backend is valid load the tensor in chunks to pinned memory and upload the buffers asynchronously to the GPU.
                 if (upload_backend) {
-                    auto offset = (off_t) weight->offs;
-                    alignment = file->read_alignment();
-                    off_t aligned_offset = offset & ~(alignment - 1);
-                    off_t offset_from_alignment = offset - aligned_offset;
-                    file->seek(aligned_offset, SEEK_SET);
-
-                    // Calculate aligned read boundaries
-                    size_t read_start = aligned_offset;
-                    size_t read_end = (offset + n_size + alignment - 1) & ~(alignment - 1);
+                    file->seek(weight->offs, SEEK_SET);
 
                     size_t bytes_read = 0;
-                    size_t data_read = 0;  // Actual tensor data copied (excluding padding)
-
-                    while (bytes_read < read_end - read_start) {
-                        size_t read_size = std::min<size_t>(buffer_size, read_end - read_start - bytes_read);
 
-                        // Align the destination pointer within the pinned buffer
-                        uintptr_t ptr_dest_aligned = (reinterpret_cast<uintptr_t>(host_ptrs[buffer_idx]) + alignment - 1) & ~(alignment - 1);
+                    while (bytes_read < n_size) {
+                        size_t read_iteration = std::min<size_t>(buffer_size, n_size - bytes_read);
 
-                        // Wait for previous upload to complete before reusing buffer
                         ggml_backend_event_synchronize(events[buffer_idx]);
-
-                        // Read aligned chunk from file
-                        file->read_raw(reinterpret_cast<void *>(ptr_dest_aligned), read_size);
-
-                        // Calculate actual data portion (excluding alignment padding)
-                        uintptr_t ptr_data = ptr_dest_aligned;
-                        size_t data_to_copy = read_size;
-
-                        // Skip alignment padding at start of first chunk
-                        if (bytes_read == 0) {
-                            ptr_data += offset_from_alignment;
-                            data_to_copy -= offset_from_alignment;
-                        }
-
-                        // Trim alignment padding at end of last chunk
-                        if (aligned_offset + bytes_read + read_size > offset + n_size) {
-                            data_to_copy -= (read_end - (offset + n_size));
-                        }
-
-                        // Async upload actual data to GPU
-                        ggml_backend_tensor_set_async(upload_backend, cur,
-                                                      reinterpret_cast<void *>(ptr_data), data_read, data_to_copy);
+                        file->read_raw(host_ptrs[buffer_idx], read_iteration);
+                        ggml_backend_tensor_set_async(upload_backend, cur, host_ptrs[buffer_idx], bytes_read, read_iteration);
                         ggml_backend_event_record(events[buffer_idx], upload_backend);
 
-                        data_read += data_to_copy;
-                        bytes_read += read_size;
-
+                        bytes_read += read_iteration;
                         ++buffer_idx;
                         buffer_idx %= n_buffers;
                     }
                 } else {
                     read_buf.resize(n_size);
-                    file->read_raw_at(read_buf.data(), n_size, weight->offs);
+                    file->seek(weight->offs, SEEK_SET);
+                    file->read_raw(read_buf.data(), n_size);
                     ggml_backend_tensor_set(cur, read_buf.data(), 0, n_size);
                     if (check_tensors && !ggml_validate_row_data(cur->type, read_buf.data(), n_size)) {
                         throw std::runtime_error(format("tensor '%s' has invalid data", ggml_get_name(cur)));
