llama : add `use_direct_io` flag for model loading (#18166)

* Adding --direct-io flag for model loading

* Fixing read_raw() calls

* Fixing Windows read_raw_at

* Changing type off_t to size_t for windows and Renaming functions

* disable direct io when mmap is explicitly enabled

* Use read_raw_unsafe when upload_backend is available, not functional on some devices with Vulkan and SYCL

* Fallback to std::fread in case O_DIRECT fails due to bad address

* Windows: remove const keywords and unused functions

* Update src/llama-mmap.cpp

Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>

---------

Co-authored-by: jtischbein <jtischbein@gmail.com>
Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>
This commit is contained in:
Julius Tischbein 2026-01-08 07:35:30 +01:00 committed by GitHub
parent 568371a726
commit 2038101bd9
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
12 changed files with 118 additions and 53 deletions

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@ -2088,11 +2088,22 @@ common_params_context common_params_parser_init(common_params & params, llama_ex
add_opt(common_arg(
{"--mmap"},
{"--no-mmap"},
string_format("whether to memory-map model (if disabled, slower load but may reduce pageouts if not using mlock) (default: %s)", params.use_mmap ? "enabled" : "disabled"),
string_format("whether to memory-map model. Explicitly enabling mmap disables direct-io. (if mmap disabled, slower load but may reduce pageouts if not using mlock) (default: %s)", params.use_mmap ? "enabled" : "disabled"),
[](common_params & params, bool value) {
params.use_mmap = value;
if (value) {
params.use_direct_io = false; // disable direct io when mmap is explicitly enabled
}
}
).set_env("LLAMA_ARG_MMAP"));
add_opt(common_arg(
{"-dio", "--direct-io"},
{"-ndio", "--no-direct-io"},
string_format("use DirectIO if available. Takes precedence over --mmap (default: %s)", params.use_direct_io ? "enabled" : "disabled"),
[](common_params & params, bool value) {
params.use_direct_io = value;
}
).set_env("LLAMA_ARG_DIO"));
add_opt(common_arg(
{"--numa"}, "TYPE",
"attempt optimizations that help on some NUMA systems\n"

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@ -1366,6 +1366,7 @@ struct llama_model_params common_model_params_to_llama(common_params & params) {
mparams.split_mode = params.split_mode;
mparams.tensor_split = params.tensor_split;
mparams.use_mmap = params.use_mmap;
mparams.use_direct_io = params.use_direct_io;
mparams.use_mlock = params.use_mlock;
mparams.check_tensors = params.check_tensors;
mparams.use_extra_bufts = !params.no_extra_bufts;

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@ -428,7 +428,8 @@ struct common_params {
bool kv_unified = false; // enable unified KV cache
bool input_prefix_bos = false; // prefix BOS to user inputs, preceding input_prefix
bool use_mmap = true; // use mmap for faster loads
bool use_mmap = true; // enable mmap to use filesystem cache
bool use_direct_io = true; // read from disk without buffering for faster model loading
bool use_mlock = false; // use mlock to keep model in memory
bool verbose_prompt = false; // print prompt tokens before generation
bool display_prompt = true; // print prompt before generation

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@ -553,6 +553,7 @@ int main(int argc, char ** argv) {
model_params.n_gpu_layers = params.n_gpu_layers;
model_params.devices = params.devices.data();
model_params.use_mmap = params.use_mmap;
model_params.use_direct_io = params.use_direct_io;
model_params.use_mlock = params.use_mlock;
model_params.check_tensors = params.check_tensors;

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@ -309,6 +309,7 @@ extern "C" {
// Keep the booleans together to avoid misalignment during copy-by-value.
bool vocab_only; // only load the vocabulary, no weights
bool use_mmap; // use mmap if possible
bool use_direct_io; // use direct io, takes precedence over use_mmap
bool use_mlock; // force system to keep model in RAM
bool check_tensors; // validate model tensor data
bool use_extra_bufts; // use extra buffer types (used for weight repacking)

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@ -110,7 +110,7 @@ struct llama_file::impl {
}
}
void read_raw(void * ptr, size_t len) const {
void read_raw(void * ptr, size_t len) {
size_t bytes_read = 0;
while (bytes_read < len) {
size_t chunk_size = std::min<size_t>(len - bytes_read, 64*1024*1024);
@ -127,7 +127,7 @@ struct llama_file::impl {
}
}
uint32_t read_u32() const {
uint32_t read_u32() {
uint32_t val;
read_raw(&val, sizeof(val));
return val;
@ -154,8 +154,8 @@ 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.");
bool has_direct_io() const {
return true;
}
~impl() {
@ -164,33 +164,45 @@ struct llama_file::impl {
}
}
#else
impl(const char * fname, const char * mode, [[maybe_unused]] const bool use_direct_io = false) {
impl(const char * fname, const char * mode, [[maybe_unused]] const bool use_direct_io = false) : fname(fname) {
#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)));
}
if (init_fd()) {
return;
}
LLAMA_LOG_WARN("Failed to open model %s with error: %s. Falling back to buffered I/O",
fname, strerror(errno));
LLAMA_LOG_WARN("Failed to open file '%s' with error: %s. Falling back to buffered I/O",
fname, strerror(errno));
}
#endif
fp = ggml_fopen(fname, mode);
init_fp(mode);
}
#ifdef __linux__
bool init_fd() {
fd = open(fname.c_str(), 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 true;
}
return false;
}
#endif
void init_fp(const char * mode) {
fp = ggml_fopen(fname.c_str(), mode);
if (fp == NULL) {
throw std::runtime_error(format("failed to open %s: %s", fname, strerror(errno)));
throw std::runtime_error(format("failed to open %s: %s", fname.c_str(), strerror(errno)));
}
seek(0, SEEK_END);
size = tell();
@ -226,7 +238,7 @@ struct llama_file::impl {
}
}
void read_raw(void * ptr, size_t len) const {
void read_raw_unsafe(void * ptr, size_t len) {
if (len == 0) {
return;
}
@ -249,6 +261,17 @@ struct llama_file::impl {
if (errno == EINTR) {
continue; // Interrupted by signal, retry
}
// Fallback to std::fread in case the DMA controller cannot access the buffer
if (errno == EFAULT) {
auto curr_off = tell();
close(fd);
fd = -1;
alignment = 1;
init_fp("rb");
seek(curr_off, SEEK_SET);
read_raw_unsafe(ptr, len);
return;
}
throw std::runtime_error(format("read error: %s", strerror(errno)));
}
if (ret == 0) {
@ -266,7 +289,8 @@ struct llama_file::impl {
}
}
void read_aligned_chunk(size_t offset, void * dest, size_t size) const {
void read_aligned_chunk(void * dest, size_t size) {
size_t offset = tell();
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);
@ -283,13 +307,21 @@ struct llama_file::impl {
std::unique_ptr<void, aligned_buffer_deleter> buffer(raw_buffer);
seek(aligned_offset, SEEK_SET);
read_raw(buffer.get(), bytes_to_read);
read_raw_unsafe(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 {
void read_raw(void * ptr, size_t len) {
if (has_direct_io()) {
read_aligned_chunk(ptr, len);
} else {
read_raw_unsafe(ptr, len);
}
}
uint32_t read_u32() {
uint32_t ret;
read_raw(&ret, sizeof(ret));
return ret;
@ -310,6 +342,10 @@ struct llama_file::impl {
write_raw(&val, sizeof(val));
}
bool has_direct_io() const {
return fd != -1 && alignment > 1;
}
~impl() {
if (fd != -1) {
close(fd);
@ -318,17 +354,9 @@ struct llama_file::impl {
}
}
int fd = -1;
std::string fname;
#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;
}
@ -347,6 +375,7 @@ 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(); }
bool llama_file::has_direct_io() const { return pimpl->has_direct_io(); }
int llama_file::file_id() const {
#ifdef _WIN32
@ -361,10 +390,14 @@ 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); }
void llama_file::read_raw(void * ptr, size_t len) { pimpl->read_raw(ptr, len); }
#ifdef _WIN32
void llama_file::read_raw_unsafe(void * ptr, size_t len) { pimpl->read_raw(ptr, len); }
#else
void llama_file::read_raw_unsafe(void * ptr, size_t len) { pimpl->read_raw_unsafe(ptr, len); }
#endif
uint32_t llama_file::read_u32() const { return pimpl->read_u32(); }
uint32_t llama_file::read_u32() { return pimpl->read_u32(); }
void llama_file::write_raw(const void * ptr, size_t len) const { pimpl->write_raw(ptr, len); }
void llama_file::write_u32(uint32_t val) const { pimpl->write_u32(val); }

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@ -24,15 +24,16 @@ 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 read_raw(void * ptr, size_t len);
void read_raw_unsafe(void * ptr, size_t len);
void read_aligned_chunk(void * dest, size_t size);
uint32_t read_u32();
void write_raw(const void * ptr, size_t len) const;
void write_u32(uint32_t val) const;
size_t read_alignment() const;
bool has_direct_io() const;
private:
struct impl;
std::unique_ptr<impl> pimpl;

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@ -495,6 +495,7 @@ llama_model_loader::llama_model_loader(
const std::string & fname,
std::vector<std::string> & splits,
bool use_mmap,
bool use_direct_io,
bool check_tensors,
bool no_alloc,
const llama_model_kv_override * param_overrides_p,
@ -527,9 +528,17 @@ 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", use_direct_io));
contexts.emplace_back(ctx);
use_direct_io = use_direct_io && files.back()->has_direct_io();
// Disable mmap in case Direct I/O is enabled and available
if (use_direct_io && use_mmap) {
use_mmap = false;
LLAMA_LOG_WARN("%s: direct I/O is enabled, disabling mmap\n", __func__);
}
// Save tensors data offset of the main file.
// For subsidiary files, `meta` tensor data offset must not be used,
// so we build a unified tensors index for weights.
@ -595,7 +604,7 @@ 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", use_direct_io));
contexts.emplace_back(ctx);
// Save tensors data offset info of the shard.
@ -739,6 +748,7 @@ llama_model_loader::llama_model_loader(
}
this->use_mmap = use_mmap;
this->use_direct_io = use_direct_io;
this->check_tensors = check_tensors;
this->no_alloc = no_alloc;
}
@ -1100,7 +1110,8 @@ bool llama_model_loader::load_all_data(
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));
@ -1132,7 +1143,7 @@ bool llama_model_loader::load_all_data(
ggml_backend_event_synchronize(events[buffer_idx]);
// Read aligned chunk from file
file->read_raw(reinterpret_cast<void *>(ptr_dest_aligned), read_size);
file->read_raw_unsafe(reinterpret_cast<void *>(ptr_dest_aligned), read_size);
// Calculate actual data portion (excluding alignment padding)
uintptr_t ptr_data = ptr_dest_aligned;
@ -1162,7 +1173,8 @@ bool llama_model_loader::load_all_data(
}
} 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)));

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@ -70,6 +70,7 @@ struct llama_model_loader {
size_t n_bytes = 0;
bool use_mmap = false;
bool use_direct_io = false;
bool check_tensors;
bool no_alloc;
@ -97,6 +98,7 @@ struct llama_model_loader {
const std::string & fname,
std::vector<std::string> & splits, // optional, only need if the split does not follow naming scheme
bool use_mmap,
bool use_direct_io,
bool check_tensors,
bool no_alloc,
const llama_model_kv_override * param_overrides_p,

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@ -2440,7 +2440,8 @@ bool llama_model::load_tensors(llama_model_loader & ml) {
const bool use_mmap_buffer = true;
LLAMA_LOG_INFO("%s: loading model tensors, this can take a while... (mmap = %s)\n", __func__, ml.use_mmap ? "true" : "false");
LLAMA_LOG_INFO("%s: loading model tensors, this can take a while... (mmap = %s, direct_io = %s)\n",
__func__, ml.use_mmap ? "true" : "false", ml.use_direct_io ? "true" : "false");
// build a list of buffer types for the CPU and GPU devices
pimpl->cpu_buft_list = make_cpu_buft_list(devices, params.use_extra_bufts, params.no_host);
@ -7973,6 +7974,7 @@ llama_model_params llama_model_default_params() {
/*.kv_overrides =*/ nullptr,
/*.vocab_only =*/ false,
/*.use_mmap =*/ true,
/*.use_direct_io =*/ true,
/*.use_mlock =*/ false,
/*.check_tensors =*/ false,
/*.use_extra_bufts =*/ true,

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@ -596,7 +596,7 @@ static void llama_model_quantize_impl(const std::string & fname_inp, const std::
}
std::vector<std::string> splits = {};
llama_model_loader ml(fname_inp, splits, use_mmap, /*check_tensors*/ true, /*no_alloc*/ false, kv_overrides, nullptr);
llama_model_loader ml(fname_inp, splits, use_mmap, /*use_direct_io*/ true, /*check_tensors*/ true, /*no_alloc*/ false, kv_overrides, nullptr);
ml.init_mappings(false); // no prefetching
llama_model model(llama_model_default_params());

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@ -794,7 +794,7 @@ static int llama_model_load(const std::string & fname, std::vector<std::string>
model.t_start_us = tm.t_start_us;
try {
llama_model_loader ml(fname, splits, params.use_mmap, params.check_tensors, params.no_alloc, params.kv_overrides, params.tensor_buft_overrides);
llama_model_loader ml(fname, splits, params.use_mmap, params.use_direct_io, params.check_tensors, params.no_alloc, params.kv_overrides, params.tensor_buft_overrides);
ml.print_info();