rebalance_interrupts/rebalance_interrupts.cpp - LeafOS-Devices/android_hardware_samsung - Gitiles

 /*
  * Copyright (C) 2021 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  *
  * rebalance-interrupts:
  *
  * One-shot distribution of unassigned* IRQs to CPU cores.
  * Useful for devices with the ARM-GIC-v3, as the Linux driver will take any
  * interrupt assigned with an all-cores mask and always have it run on core 0.
  *
  * This should be run once, long enough after boot that all drivers have
  * registered their interrupts.
  *
  * This program is configured to spread the load across all the cores in
  * CPUFREQ policy 0.  This is because other cores may be hotplugged in
  * or out, and if hotplugged out the interrupts would be sent to core0 always.
  *
  * It might be wise to avoid core0 so that any later-added IRQs don't overcrowd
  * core 0.
  *
  * Any program that has an actual IRQ related performance constraint should
  * override any settings assigned by this and assign the IRQ to the same
  * core as the code whose performance is impacted by the IRQ.
  *
  */

 #include <sys/types.h>
 #include <dirent.h>

 #include <iostream>
 #include <list>
 #include <map>
 #include <vector>

 #define LOG_TAG "rebalance_interrupts"

 #include <android-base/file.h>
 #include <android-base/format.h>
 #include <android-base/logging.h>
 #include <android-base/parseint.h>
 #include <android-base/strings.h>


 #define POLICY0_CORES_PATH "/sys/devices/system/cpu/cpufreq/policy0/affected_cpus"
 #define SYSFS_IRQDIR "/sys/kernel/irq"
 #define PROC_IRQDIR "/proc/irq"

 using android::base::ParseInt;
 using android::base::ParseUint;
 using android::base::ReadFileToString;
 using android::base::Trim;
 using android::base::WriteStringToFile;
 using std::list;
 using std::map;
 using std::pair;
 using std::string;
 using std::vector;

 // Return a vector of strings describing the affected CPUs for cpufreq
 // Policy 0.
 vector<int> Policy0AffectedCpus() {
   string policy0_cores_unparsed;
   if (!ReadFileToString(POLICY0_CORES_PATH, &policy0_cores_unparsed))
     return vector<int>();
   string policy0_trimmed = android::base::Trim(policy0_cores_unparsed);
   vector<string> cpus_as_string = android::base::Split(policy0_trimmed, " ");

   vector<int> cpus_as_int;
   for (int i = 0; i < cpus_as_string.size(); ++i) {
     int cpu;
     if (!ParseInt(cpus_as_string[i].c_str(), &cpu))
       return vector<int>();
     cpus_as_int.push_back(cpu);
   }
   return cpus_as_int;
 }

 // Return a vector of strings describing the CPU masks for cpufreq Policy 0.
 vector<string> Policy0CpuMasks() {
   vector<int> cpus = Policy0AffectedCpus();
   vector<string> cpu_masks;
   for (int i = 0; i < cpus.size(); ++i)
     cpu_masks.push_back(fmt::format("{0:02x}", 1 << cpus[i]));
   return cpu_masks;
 }

 // Read the actions for the given irq# from sysfs, and add it to action_to_irq
 bool AddEntryToIrqmap(const char* irq,
                       map<string, list<string>>& action_to_irqs) {
   const string irq_base(SYSFS_IRQDIR "/");
   string irq_actions_path = irq_base + irq + "/actions";

   string irq_actions;
   if (!ReadFileToString(irq_actions_path, &irq_actions))
     return false;

   irq_actions = Trim(irq_actions);

   if (irq_actions == "(null)")
     irq_actions = "";

   action_to_irqs[irq_actions].push_back(irq);

   return true;
 }

 // Get a mapping of driver "action" to IRQ#s for each IRQ# in
 // SYSFS_IRQDIR.
 bool GetIrqmap(map<string, list<string>>& action_to_irqs) {
   bool some_success = false;
   std::unique_ptr<DIR, decltype(&closedir)> irq_dir(opendir(SYSFS_IRQDIR), closedir);
   if (!irq_dir) {
     PLOG(ERROR) << "opening dir " SYSFS_IRQDIR;
     return false;
   }

   struct dirent* entry;
   while ((entry = readdir(irq_dir.get()))) {

     // If the directory entry isn't a parsable number, skip it.
     // . and .. get skipped here.
     unsigned throwaway;
     if (!ParseUint(entry->d_name, &throwaway))
       continue;

     some_success |= AddEntryToIrqmap(entry->d_name, action_to_irqs);
   }
   return some_success;
 }

 // Given a map of irq actions -> IRQs,
 // find out which ones haven't been assigned and add those to
 // rebalance_actions.
 void FindUnassignedIrqs(const map<string, list<string>>& action_to_irqs,
                         list<pair<string, list<string>>>& rebalance_actions) {
   for (const auto &action_to_irqs_entry: action_to_irqs) {
     bool rebalance = true;
     for (const auto& irq: action_to_irqs_entry.second) {
       string smp_affinity;
       string proc_path(PROC_IRQDIR "/");
       proc_path += irq + "/smp_affinity";
       ReadFileToString(proc_path, &smp_affinity);
       smp_affinity = Trim(smp_affinity);

       // Try to respect previoulsy set IRQ affinities.
       // On ARM interrupt controllers under Linux, if an IRQ is assigned
       // to more than one core it will only be assigned to the lowest core.
       // Assume any IRQ which is set to more than one core in the lowest four
       // CPUs hasn't been assigned and needs to be rebalanced.
       if (smp_affinity.back() == '0' ||
           smp_affinity.back() == '1' ||
           smp_affinity.back() == '2' ||
           smp_affinity.back() == '4' ||
           smp_affinity.back() == '8') {
         rebalance = false;
       }

       // Treat each unnamed action IRQ as independent.
       if (action_to_irqs_entry.first.empty()) {
         if (rebalance) {
           pair<string, list<string>> empty_action_irq;
           empty_action_irq.first = "";
           empty_action_irq.second.push_back(irq);
           rebalance_actions.push_back(empty_action_irq);
         }
         rebalance = true;
       }
     }
     if (rebalance && !action_to_irqs_entry.first.empty()) {
       rebalance_actions.push_back(std::make_pair(action_to_irqs_entry.first,
                                                  action_to_irqs_entry.second));
     }
   }
 }

 // Read the file at `path`, Trim whitespace, see if it matches `expected_value`.
 // Print the results to stdout.
 void ReportIfAffinityUpdated(const std::string expected_value,
                              const std::string path) {
   std::string readback, report;
   ReadFileToString(path, &readback);
   readback = Trim(readback);
   if (readback != expected_value) {
     report += "Unable to set ";
   } else {
     report += "Success setting ";
   }
   report += path;
   report += ": found " + readback + " vs " + expected_value + "\n";
   LOG(DEBUG) << report;
 }

 // Evenly distribute the IRQ actions across all the Policy0 CPUs.
 // Assign all the IRQs of an action to a single CPU core.
 bool RebalanceIrqs(const list<pair<string, list<string>>>& action_to_irqs) {
   int mask_index = 0;
   std::vector<std::string> affinity_masks = Policy0CpuMasks();

   if (affinity_masks.empty()) {
     LOG(ERROR) << "Unable to find Policy0 CPUs for IRQ assignment.";
     return false;
   }

   for (const auto &action_to_irq: action_to_irqs) {
     for (const auto& irq: action_to_irq.second) {
       std::string affinity_path(PROC_IRQDIR "/");
       affinity_path += irq + "/smp_affinity";
       WriteStringToFile(affinity_masks[mask_index], affinity_path);
       ReportIfAffinityUpdated(affinity_masks[mask_index], affinity_path);
     }
     mask_index = (mask_index + 1) % affinity_masks.size();
   }
   return true;
 }

 int main(int /* argc */, char* /* argv */[]) {
   map<string, list<string>> irq_mapping;
   list<pair<string, list<string>>> action_to_irqs;

   // Find the mapping of "irq actions" to IRQs.
   // Each IRQ has an assocatied irq_actions field, showing the actions
   // associated with it.  Multiple IRQs have the same actions.
   // Generate the mapping of actions to IRQs with that action,
   // as these IRQs should all be mapped to the same cores.
   if (!GetIrqmap(irq_mapping)) {
     LOG(ERROR) << "Unable to read IRQ mappings.  Are you root?";
     return 1;
   }

   // Some IRQs are already assigned to a subset of cores, usually for
   // good reason (like some drivers have an IRQ per core, for per-core
   // queues.)  Find the set of IRQs that haven't been mapped to specific
   // cores.
   FindUnassignedIrqs(irq_mapping, action_to_irqs);

   // Distribute the rebalancable IRQs across all cores.
   return RebalanceIrqs(action_to_irqs) ? 0 : 1;
 }
	/*
	* Copyright (C) 2021 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*
	* rebalance-interrupts:
	*
	* One-shot distribution of unassigned* IRQs to CPU cores.
	* Useful for devices with the ARM-GIC-v3, as the Linux driver will take any
	* interrupt assigned with an all-cores mask and always have it run on core 0.
	*
	* This should be run once, long enough after boot that all drivers have
	* registered their interrupts.
	*
	* This program is configured to spread the load across all the cores in
	* CPUFREQ policy 0. This is because other cores may be hotplugged in
	* or out, and if hotplugged out the interrupts would be sent to core0 always.
	*
	* It might be wise to avoid core0 so that any later-added IRQs don't overcrowd
	* core 0.
	*
	* Any program that has an actual IRQ related performance constraint should
	* override any settings assigned by this and assign the IRQ to the same
	* core as the code whose performance is impacted by the IRQ.
	*
	*/

	#include <sys/types.h>
	#include <dirent.h>

	#include <iostream>
	#include <list>
	#include <map>
	#include <vector>

	#define LOG_TAG "rebalance_interrupts"

	#include <android-base/file.h>
	#include <android-base/format.h>
	#include <android-base/logging.h>
	#include <android-base/parseint.h>
	#include <android-base/strings.h>


	#define POLICY0_CORES_PATH "/sys/devices/system/cpu/cpufreq/policy0/affected_cpus"
	#define SYSFS_IRQDIR "/sys/kernel/irq"
	#define PROC_IRQDIR "/proc/irq"

	using android::base::ParseInt;
	using android::base::ParseUint;
	using android::base::ReadFileToString;
	using android::base::Trim;
	using android::base::WriteStringToFile;
	using std::list;
	using std::map;
	using std::pair;
	using std::string;
	using std::vector;

	// Return a vector of strings describing the affected CPUs for cpufreq
	// Policy 0.
	vector<int> Policy0AffectedCpus() {
	string policy0_cores_unparsed;
	if (!ReadFileToString(POLICY0_CORES_PATH, &policy0_cores_unparsed))
	return vector<int>();
	string policy0_trimmed = android::base::Trim(policy0_cores_unparsed);
	vector<string> cpus_as_string = android::base::Split(policy0_trimmed, " ");

	vector<int> cpus_as_int;
	for (int i = 0; i < cpus_as_string.size(); ++i) {
	int cpu;
	if (!ParseInt(cpus_as_string[i].c_str(), &cpu))
	return vector<int>();
	cpus_as_int.push_back(cpu);
	}
	return cpus_as_int;
	}

	// Return a vector of strings describing the CPU masks for cpufreq Policy 0.
	vector<string> Policy0CpuMasks() {
	vector<int> cpus = Policy0AffectedCpus();
	vector<string> cpu_masks;
	for (int i = 0; i < cpus.size(); ++i)
	cpu_masks.push_back(fmt::format("{0:02x}", 1 << cpus[i]));
	return cpu_masks;
	}

	// Read the actions for the given irq# from sysfs, and add it to action_to_irq
	bool AddEntryToIrqmap(const char* irq,
	map<string, list<string>>& action_to_irqs) {
	const string irq_base(SYSFS_IRQDIR "/");
	string irq_actions_path = irq_base + irq + "/actions";

	string irq_actions;
	if (!ReadFileToString(irq_actions_path, &irq_actions))
	return false;

	irq_actions = Trim(irq_actions);

	if (irq_actions == "(null)")
	irq_actions = "";

	action_to_irqs[irq_actions].push_back(irq);

	return true;
	}

	// Get a mapping of driver "action" to IRQ#s for each IRQ# in
	// SYSFS_IRQDIR.
	bool GetIrqmap(map<string, list<string>>& action_to_irqs) {
	bool some_success = false;
	std::unique_ptr<DIR, decltype(&closedir)> irq_dir(opendir(SYSFS_IRQDIR), closedir);
	if (!irq_dir) {
	PLOG(ERROR) << "opening dir " SYSFS_IRQDIR;
	return false;
	}

	struct dirent* entry;
	while ((entry = readdir(irq_dir.get()))) {

	// If the directory entry isn't a parsable number, skip it.
	// . and .. get skipped here.
	unsigned throwaway;
	if (!ParseUint(entry->d_name, &throwaway))
	continue;

	some_success \|= AddEntryToIrqmap(entry->d_name, action_to_irqs);
	}
	return some_success;
	}

	// Given a map of irq actions -> IRQs,
	// find out which ones haven't been assigned and add those to
	// rebalance_actions.
	void FindUnassignedIrqs(const map<string, list<string>>& action_to_irqs,
	list<pair<string, list<string>>>& rebalance_actions) {
	for (const auto &action_to_irqs_entry: action_to_irqs) {
	bool rebalance = true;
	for (const auto& irq: action_to_irqs_entry.second) {
	string smp_affinity;
	string proc_path(PROC_IRQDIR "/");
	proc_path += irq + "/smp_affinity";
	ReadFileToString(proc_path, &smp_affinity);
	smp_affinity = Trim(smp_affinity);

	// Try to respect previoulsy set IRQ affinities.
	// On ARM interrupt controllers under Linux, if an IRQ is assigned
	// to more than one core it will only be assigned to the lowest core.
	// Assume any IRQ which is set to more than one core in the lowest four
	// CPUs hasn't been assigned and needs to be rebalanced.
	if (smp_affinity.back() == '0' \|\|
	smp_affinity.back() == '1' \|\|
	smp_affinity.back() == '2' \|\|
	smp_affinity.back() == '4' \|\|
	smp_affinity.back() == '8') {
	rebalance = false;
	}

	// Treat each unnamed action IRQ as independent.
	if (action_to_irqs_entry.first.empty()) {
	if (rebalance) {
	pair<string, list<string>> empty_action_irq;
	empty_action_irq.first = "";
	empty_action_irq.second.push_back(irq);
	rebalance_actions.push_back(empty_action_irq);
	}
	rebalance = true;
	}
	}
	if (rebalance && !action_to_irqs_entry.first.empty()) {
	rebalance_actions.push_back(std::make_pair(action_to_irqs_entry.first,
	action_to_irqs_entry.second));
	}
	}
	}

	// Read the file at `path`, Trim whitespace, see if it matches `expected_value`.
	// Print the results to stdout.
	void ReportIfAffinityUpdated(const std::string expected_value,
	const std::string path) {
	std::string readback, report;
	ReadFileToString(path, &readback);
	readback = Trim(readback);
	if (readback != expected_value) {
	report += "Unable to set ";
	} else {
	report += "Success setting ";
	}
	report += path;
	report += ": found " + readback + " vs " + expected_value + "\n";
	LOG(DEBUG) << report;
	}

	// Evenly distribute the IRQ actions across all the Policy0 CPUs.
	// Assign all the IRQs of an action to a single CPU core.
	bool RebalanceIrqs(const list<pair<string, list<string>>>& action_to_irqs) {
	int mask_index = 0;
	std::vector<std::string> affinity_masks = Policy0CpuMasks();

	if (affinity_masks.empty()) {
	LOG(ERROR) << "Unable to find Policy0 CPUs for IRQ assignment.";
	return false;
	}

	for (const auto &action_to_irq: action_to_irqs) {
	for (const auto& irq: action_to_irq.second) {
	std::string affinity_path(PROC_IRQDIR "/");
	affinity_path += irq + "/smp_affinity";
	WriteStringToFile(affinity_masks[mask_index], affinity_path);
	ReportIfAffinityUpdated(affinity_masks[mask_index], affinity_path);
	}
	mask_index = (mask_index + 1) % affinity_masks.size();
	}
	return true;
	}

	int main(int /* argc /, char /* argv */[]) {
	map<string, list<string>> irq_mapping;
	list<pair<string, list<string>>> action_to_irqs;

	// Find the mapping of "irq actions" to IRQs.
	// Each IRQ has an assocatied irq_actions field, showing the actions
	// associated with it. Multiple IRQs have the same actions.
	// Generate the mapping of actions to IRQs with that action,
	// as these IRQs should all be mapped to the same cores.
	if (!GetIrqmap(irq_mapping)) {
	LOG(ERROR) << "Unable to read IRQ mappings. Are you root?";
	return 1;
	}

	// Some IRQs are already assigned to a subset of cores, usually for
	// good reason (like some drivers have an IRQ per core, for per-core
	// queues.) Find the set of IRQs that haven't been mapped to specific
	// cores.
	FindUnassignedIrqs(irq_mapping, action_to_irqs);

	// Distribute the rebalancable IRQs across all cores.
	return RebalanceIrqs(action_to_irqs) ? 0 : 1;
	}