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Improve performance on NUMA systems
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Allow for NUMA memory replication for NNUE weights.  Bind threads to ensure execution on a specific NUMA node.

This patch introduces NUMA memory replication, currently only utilized for the NNUE weights. Along with it comes all machinery required to identify NUMA nodes and bind threads to specific processors/nodes. It also comes with small changes to Thread and ThreadPool to allow easier execution of custom functions on the designated thread. Old thread binding (WinProcGroup) machinery is removed because it's incompatible with this patch. Small changes to unrelated parts of the code were made to ensure correctness, like some classes being made unmovable, raw pointers replaced with unique_ptr. etc.

Windows 7 and Windows 10 is partially supported. Windows 11 is fully supported. Linux is fully supported, with explicit exclusion of Android. No additional dependencies.

-----------------

A new UCI option `NumaPolicy` is introduced. It can take the following values:
```
system - gathers NUMA node information from the system (lscpu or windows api), for each threads binds it to a single NUMA node
none - assumes there is 1 NUMA node, never binds threads
auto - this is the default value, depends on the number of set threads and NUMA nodes, will only enable binding on multinode systems and when the number of threads reaches a threshold (dependent on node size and count)
[[custom]] -
  // ':'-separated numa nodes
  // ','-separated cpu indices
  // supports "first-last" range syntax for cpu indices,
  for example '0-15,32-47:16-31,48-63'
```

Setting `NumaPolicy` forces recreation of the threads in the ThreadPool, which in turn forces the recreation of the TT.

The threads are distributed among NUMA nodes in a round-robin fashion based on fill percentage (i.e. it will strive to fill all NUMA nodes evenly). Threads are bound to NUMA nodes, not specific processors, because that's our only requirement and the OS can schedule them better.

Special care is made that maximum memory usage on systems that do not require memory replication stays as previously, that is, unnecessary copies are avoided.

On linux the process' processor affinity is respected. This means that if you for example use taskset to restrict Stockfish to a single NUMA node then the `system` and `auto` settings will only see a single NUMA node (more precisely, the processors included in the current affinity mask) and act accordingly.

-----------------

We can't ensure that a memory allocation takes place on a given NUMA node without using libnuma on linux, or using appropriate custom allocators on windows (https://learn.microsoft.com/en-us/windows/win32/memory/allocating-memory-from-a-numa-node), so to avoid complications the current implementation relies on first-touch policy. Due to this we also rely on the memory allocator to give us a new chunk of untouched memory from the system. This appears to work reliably on linux, but results may vary.

MacOS is not supported, because AFAIK it's not affected, and implementation would be problematic anyway.

Windows is supported since Windows 7 (https://learn.microsoft.com/en-us/windows/win32/api/processtopologyapi/nf-processtopologyapi-setthreadgroupaffinity). Until Windows 11/Server 2022 NUMA nodes are split such that they cannot span processor groups. This is because before Windows 11/Server 2022 it's not possible to set thread affinity spanning processor groups. The splitting is done manually in some cases (required after Windows 10 Build 20348). Since Windows 11/Server 2022 we can set affinites spanning processor group so this splitting is not done, so the behaviour is pretty much like on linux.

Linux is supported, **without** libnuma requirement. `lscpu` is expected.

-----------------

Passed 60+1 @ 256t 16000MB hash: https://tests.stockfishchess.org/tests/view/6654e443a86388d5e27db0d8
```
LLR: 2.95 (-2.94,2.94) <0.00,10.00>
Total: 278 W: 110 L: 29 D: 139
Ptnml(0-2): 0, 1, 56, 82, 0
```

Passed SMP STC: https://tests.stockfishchess.org/tests/view/6654fc74a86388d5e27db1cd
```
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 67152 W: 17354 L: 17177 D: 32621
Ptnml(0-2): 64, 7428, 18408, 7619, 57
```

Passed STC: https://tests.stockfishchess.org/tests/view/6654fb27a86388d5e27db15c
```
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 131648 W: 34155 L: 34045 D: 63448
Ptnml(0-2): 426, 13878, 37096, 14008, 416
```

fixes official-stockfish#5253
closes official-stockfish#5285

No functional change
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@Sopel97 @Disservin
Sopel97 authored and Disservin committed May 28, 2024
1 parent b0287dc commit bb822b6
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1 change: 1 addition & 0 deletions .github/ci/libcxx17.imp
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Expand Up @@ -7,6 +7,7 @@
{ include: [ "<__fwd/sstream.h>", private, "<iosfwd>", public ] },
{ include: [ "<__fwd/streambuf.h>", private, "<iosfwd>", public ] },
{ include: [ "<__fwd/string_view.h>", private, "<string_view>", public ] },
{ include: [ "<__system_error/errc.h>", private, "<system_error>", public ] },

# Mappings for includes between public headers
{ include: [ "<ios>", public, "<iostream>", public ] },
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2 changes: 1 addition & 1 deletion src/Makefile
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Expand Up @@ -63,7 +63,7 @@ HEADERS = benchmark.h bitboard.h evaluate.h misc.h movegen.h movepick.h \
nnue/layers/sqr_clipped_relu.h nnue/nnue_accumulator.h nnue/nnue_architecture.h \
nnue/nnue_common.h nnue/nnue_feature_transformer.h position.h \
search.h syzygy/tbprobe.h thread.h thread_win32_osx.h timeman.h \
tt.h tune.h types.h uci.h ucioption.h perft.h nnue/network.h engine.h score.h
tt.h tune.h types.h uci.h ucioption.h perft.h nnue/network.h engine.h score.h numa.h

OBJS = $(notdir $(SRCS:.cpp=.o))

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88 changes: 70 additions & 18 deletions src/engine.cpp
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Expand Up @@ -18,15 +18,15 @@

#include "engine.h"

#include <cassert>
#include <deque>
#include <iosfwd>
#include <memory>
#include <ostream>
#include <sstream>
#include <string_view>
#include <utility>
#include <vector>
#include <sstream>
#include <iosfwd>
#include <cassert>

#include "evaluate.h"
#include "misc.h"
Expand All @@ -48,10 +48,14 @@ constexpr auto StartFEN = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq -

Engine::Engine(std::string path) :
binaryDirectory(CommandLine::get_binary_directory(path)),
numaContext(NumaConfig::from_system()),
states(new std::deque<StateInfo>(1)),
networks(NN::Networks(
NN::NetworkBig({EvalFileDefaultNameBig, "None", ""}, NN::EmbeddedNNUEType::BIG),
NN::NetworkSmall({EvalFileDefaultNameSmall, "None", ""}, NN::EmbeddedNNUEType::SMALL))) {
threads(),
networks(
numaContext,
NN::Networks(
NN::NetworkBig({EvalFileDefaultNameBig, "None", ""}, NN::EmbeddedNNUEType::BIG),
NN::NetworkSmall({EvalFileDefaultNameSmall, "None", ""}, NN::EmbeddedNNUEType::SMALL))) {
pos.set(StartFEN, false, &states->back());
capSq = SQ_NONE;
}
Expand All @@ -74,7 +78,7 @@ void Engine::stop() { threads.stop = true; }
void Engine::search_clear() {
wait_for_search_finished();

tt.clear(options["Threads"]);
tt.clear(threads);
threads.clear();

// @TODO wont work with multiple instances
Expand Down Expand Up @@ -124,40 +128,71 @@ void Engine::set_position(const std::string& fen, const std::vector<std::string>

// modifiers

void Engine::resize_threads() { threads.set({options, threads, tt, networks}, updateContext); }
void Engine::set_numa_config_from_option(const std::string& o) {
if (o == "auto" || o == "system")
{
numaContext.set_numa_config(NumaConfig::from_system());
}
else if (o == "none")
{
numaContext.set_numa_config(NumaConfig{});
}
else
{
numaContext.set_numa_config(NumaConfig::from_string(o));
}

// Force reallocation of threads in case affinities need to change.
resize_threads();
}

void Engine::resize_threads() {
threads.wait_for_search_finished();
threads.set(numaContext.get_numa_config(), {options, threads, tt, networks}, updateContext);

// Reallocate the hash with the new threadpool size
set_tt_size(options["Hash"]);
}

void Engine::set_tt_size(size_t mb) {
wait_for_search_finished();
tt.resize(mb, options["Threads"]);
tt.resize(mb, threads);
}

void Engine::set_ponderhit(bool b) { threads.main_manager()->ponder = b; }

// network related

void Engine::verify_networks() const {
networks.big.verify(options["EvalFile"]);
networks.small.verify(options["EvalFileSmall"]);
networks->big.verify(options["EvalFile"]);
networks->small.verify(options["EvalFileSmall"]);
}

void Engine::load_networks() {
load_big_network(options["EvalFile"]);
load_small_network(options["EvalFileSmall"]);
networks.modify_and_replicate([this](NN::Networks& networks_) {
networks_.big.load(binaryDirectory, options["EvalFile"]);
networks_.small.load(binaryDirectory, options["EvalFileSmall"]);
});
threads.clear();
}

void Engine::load_big_network(const std::string& file) {
networks.big.load(binaryDirectory, file);
networks.modify_and_replicate(
[this, &file](NN::Networks& networks_) { networks_.big.load(binaryDirectory, file); });
threads.clear();
}

void Engine::load_small_network(const std::string& file) {
networks.small.load(binaryDirectory, file);
networks.modify_and_replicate(
[this, &file](NN::Networks& networks_) { networks_.small.load(binaryDirectory, file); });
threads.clear();
}

void Engine::save_network(const std::pair<std::optional<std::string>, std::string> files[2]) {
networks.big.save(files[0].first);
networks.small.save(files[1].first);
networks.modify_and_replicate([&files](NN::Networks& networks_) {
networks_.big.save(files[0].first);
networks_.small.save(files[1].first);
});
}

// utility functions
Expand All @@ -169,7 +204,7 @@ void Engine::trace_eval() const {

verify_networks();

sync_cout << "\n" << Eval::trace(p, networks) << sync_endl;
sync_cout << "\n" << Eval::trace(p, *networks) << sync_endl;
}

OptionsMap& Engine::get_options() { return options; }
Expand All @@ -184,4 +219,21 @@ std::string Engine::visualize() const {
return ss.str();
}

std::vector<std::pair<size_t, size_t>> Engine::get_bound_thread_count_by_numa_node() const {
auto counts = threads.get_bound_thread_count_by_numa_node();
const NumaConfig& cfg = numaContext.get_numa_config();
std::vector<std::pair<size_t, size_t>> ratios;
NumaIndex n = 0;
for (; n < counts.size(); ++n)
ratios.emplace_back(counts[n], cfg.num_cpus_in_numa_node(n));
if (!counts.empty())
for (; n < cfg.num_numa_nodes(); ++n)
ratios.emplace_back(0, cfg.num_cpus_in_numa_node(n));
return ratios;
}

std::string Engine::get_numa_config_as_string() const {
return numaContext.get_numa_config().to_string();
}

}
31 changes: 22 additions & 9 deletions src/engine.h
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Expand Up @@ -35,6 +35,7 @@
#include "thread.h"
#include "tt.h"
#include "ucioption.h"
#include "numa.h"

namespace Stockfish {

Expand All @@ -47,6 +48,13 @@ class Engine {
using InfoIter = Search::InfoIteration;

Engine(std::string path = "");

// Can't be movable due to components holding backreferences to fields
Engine(const Engine&) = delete;
Engine(Engine&&) = delete;
Engine& operator=(const Engine&) = delete;
Engine& operator=(Engine&&) = delete;

~Engine() { wait_for_search_finished(); }

std::uint64_t perft(const std::string& fen, Depth depth, bool isChess960);
Expand All @@ -63,6 +71,7 @@ class Engine {

// modifiers

void set_numa_config_from_option(const std::string& o);
void resize_threads();
void set_tt_size(size_t mb);
void set_ponderhit(bool);
Expand All @@ -83,23 +92,27 @@ class Engine {

// utility functions

void trace_eval() const;
OptionsMap& get_options();
std::string fen() const;
void flip();
std::string visualize() const;
void trace_eval() const;
OptionsMap& get_options();
std::string fen() const;
void flip();
std::string visualize() const;
std::vector<std::pair<size_t, size_t>> get_bound_thread_count_by_numa_node() const;
std::string get_numa_config_as_string() const;

private:
const std::string binaryDirectory;

NumaReplicationContext numaContext;

Position pos;
StateListPtr states;
Square capSq;

OptionsMap options;
ThreadPool threads;
TranspositionTable tt;
Eval::NNUE::Networks networks;
OptionsMap options;
ThreadPool threads;
TranspositionTable tt;
NumaReplicated<Eval::NNUE::Networks> networks;

Search::SearchManager::UpdateContext updateContext;
};
Expand Down
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