Load kernel modules in parallel
First, we load independent module in parallel, then we singly load
modules which have soft-dependencies. then remove them from dependency
list of other modules. Repeat these steps until all modules are loaded.
Bug: 180676019
Test: boot successfully, and save more than 400 ms on Pixel 6 Pro.
Signed-off-by: chungkai <chungkai@google.com>
Change-Id: Ib844cfee72d4049bd951528692c818b4fa6c8e8f
diff --git a/libmodprobe/libmodprobe.cpp b/libmodprobe/libmodprobe.cpp
index 1a9d364..3054d2b 100644
--- a/libmodprobe/libmodprobe.cpp
+++ b/libmodprobe/libmodprobe.cpp
@@ -21,8 +21,10 @@
#include <sys/syscall.h>
#include <algorithm>
+#include <map>
#include <set>
#include <string>
+#include <thread>
#include <vector>
#include <android-base/chrono_utils.h>
@@ -437,6 +439,97 @@
return module_blocklist_.count(canonical_name) > 0;
}
+// Another option to load kernel modules. load in independent modules in parallel
+// and then load modules which only have soft dependency, third update dependency list of other
+// remaining modules, repeat these steps until all modules are loaded.
+bool Modprobe::LoadModulesParallel(int num_threads) {
+ bool ret = true;
+ std::map<std::string, std::set<std::string>> mod_with_deps;
+ std::map<std::string, std::set<std::string>> mod_with_softdeps;
+
+ // Get dependencies
+ for (const auto& module : module_load_) {
+ auto dependencies = GetDependencies(MakeCanonical(module));
+
+ for (auto dep = dependencies.rbegin(); dep != dependencies.rend(); dep++) {
+ mod_with_deps[module].emplace(*dep);
+ }
+ }
+
+ // Get soft dependencies
+ for (const auto& [it_mod, it_softdep] : module_pre_softdep_) {
+ mod_with_softdeps[MakeCanonical(it_mod)].emplace(it_softdep);
+ }
+
+ // Get soft post dependencies
+ for (const auto& [it_mod, it_softdep] : module_post_softdep_) {
+ mod_with_softdeps[MakeCanonical(it_mod)].emplace(it_softdep);
+ }
+
+ while (!mod_with_deps.empty()) {
+ std::vector<std::thread> threads;
+ std::vector<std::string> mods_path_to_load;
+ std::vector<std::string> mods_with_softdep_to_load;
+ std::mutex vector_lock;
+
+ // Find independent modules and modules only having soft dependencies
+ for (const auto& [it_mod, it_dep] : mod_with_deps) {
+ if (it_dep.size() == 1 && mod_with_softdeps[it_mod].empty()) {
+ mods_path_to_load.emplace_back(*(it_dep.begin()));
+ } else if (it_dep.size() == 1) {
+ mods_with_softdep_to_load.emplace_back(it_mod);
+ }
+ }
+
+ // Load independent modules in parallel
+ auto thread_function = [&] {
+ std::unique_lock lk(vector_lock);
+ while (!mods_path_to_load.empty()) {
+ auto mod_path_to_load = std::move(mods_path_to_load.back());
+ mods_path_to_load.pop_back();
+
+ lk.unlock();
+ ret &= Insmod(mod_path_to_load, "");
+ lk.lock();
+ }
+ };
+
+ std::generate_n(std::back_inserter(threads), num_threads,
+ [&] { return std::thread(thread_function); });
+
+ // Wait for the threads.
+ for (auto& thread : threads) {
+ thread.join();
+ }
+
+ // Since we cannot assure if these soft dependencies tree are overlap,
+ // we loaded these modules one by one.
+ for (auto dep = mods_with_softdep_to_load.rbegin(); dep != mods_with_softdep_to_load.rend();
+ dep++) {
+ ret &= LoadWithAliases(*dep, true);
+ }
+
+ std::lock_guard guard(module_loaded_lock_);
+ // Remove loaded module form mod_with_deps and soft dependencies of other modules
+ for (const auto& module_loaded : module_loaded_) {
+ mod_with_deps.erase(module_loaded);
+
+ for (auto& [mod, softdeps] : mod_with_softdeps) {
+ softdeps.erase(module_loaded);
+ }
+ }
+
+ // Remove loaded module form dependencies of other modules which are not loaded yet
+ for (const auto& module_loaded_path : module_loaded_paths_) {
+ for (auto& [mod, deps] : mod_with_deps) {
+ deps.erase(module_loaded_path);
+ }
+ }
+ }
+
+ return ret;
+}
+
bool Modprobe::LoadListedModules(bool strict) {
auto ret = true;
for (const auto& module : module_load_) {