blob: 1e2862f024e491abff0fef3ed1b80d8d9f14df31 [file] [log] [blame]
// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/process/process.h"
#include <errno.h>
#include <sys/resource.h>
#include "base/files/file_util.h"
#include "base/logging.h"
#include "base/posix/can_lower_nice_to.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_split.h"
#include "base/strings/stringprintf.h"
#include "base/synchronization/lock.h"
#include "base/threading/thread_restrictions.h"
#include "build/build_config.h"
namespace base {
namespace {
const int kForegroundPriority = 0;
#if defined(OS_CHROMEOS)
// We are more aggressive in our lowering of background process priority
// for chromeos as we have much more control over other processes running
// on the machine.
// TODO(davemoore) Refactor this by adding support for higher levels to set
// the foregrounding / backgrounding process so we don't have to keep
// chrome / chromeos specific logic here.
const int kBackgroundPriority = 19;
const char kControlPath[] = "/sys/fs/cgroup/cpu%s/cgroup.procs";
const char kForeground[] = "/chrome_renderers/foreground";
const char kBackground[] = "/chrome_renderers/background";
const char kProcPath[] = "/proc/%d/cgroup";
struct CGroups {
// Check for cgroups files. ChromeOS supports these by default. It creates
// a cgroup mount in /sys/fs/cgroup and then configures two cpu task groups,
// one contains at most a single foreground renderer and the other contains
// all background renderers. This allows us to limit the impact of background
// renderers on foreground ones to a greater level than simple renicing.
bool enabled;
base::FilePath foreground_file;
base::FilePath background_file;
CGroups() {
foreground_file =
base::FilePath(base::StringPrintf(kControlPath, kForeground));
background_file =
base::FilePath(base::StringPrintf(kControlPath, kBackground));
base::FileSystemType foreground_type;
base::FileSystemType background_type;
enabled =
base::GetFileSystemType(foreground_file, &foreground_type) &&
base::GetFileSystemType(background_file, &background_type) &&
foreground_type == FILE_SYSTEM_CGROUP &&
background_type == FILE_SYSTEM_CGROUP;
static CGroups& Get() {
static auto& groups = *new CGroups;
return groups;
const int kBackgroundPriority = 5;
#endif // defined(OS_CHROMEOS)
} // namespace
// static
bool Process::CanBackgroundProcesses() {
#if defined(OS_CHROMEOS)
if (CGroups::Get().enabled)
return true;
#endif // defined(OS_CHROMEOS)
static const bool can_reraise_priority =
return can_reraise_priority;
bool Process::IsProcessBackgrounded() const {
#if defined(OS_CHROMEOS)
if (CGroups::Get().enabled) {
// Used to allow reading the process priority from proc on thread launch.
base::ThreadRestrictions::ScopedAllowIO allow_io;
std::string proc;
if (base::ReadFileToString(
base::FilePath(StringPrintf(kProcPath, process_)), &proc)) {
return IsProcessBackgroundedCGroup(proc);
return false;
#endif // defined(OS_CHROMEOS)
return GetPriority() == kBackgroundPriority;
bool Process::SetProcessBackgrounded(bool background) {
#if defined(OS_CHROMEOS)
if (CGroups::Get().enabled) {
std::string pid = IntToString(process_);
const base::FilePath file = background ? CGroups::Get().background_file
: CGroups::Get().foreground_file;
return base::WriteFile(file, pid.c_str(), pid.size()) > 0;
#endif // defined(OS_CHROMEOS)
if (!CanBackgroundProcesses())
return false;
int priority = background ? kBackgroundPriority : kForegroundPriority;
int result = setpriority(PRIO_PROCESS, process_, priority);
DPCHECK(result == 0);
return result == 0;
#if defined(OS_CHROMEOS)
bool IsProcessBackgroundedCGroup(const StringPiece& cgroup_contents) {
// The process can be part of multiple control groups, and for each cgroup
// hierarchy there's an entry in the file. We look for a control group
// named "/chrome_renderers/background" to determine if the process is
// backgrounded.
std::vector<StringPiece> lines = SplitStringPiece(
for (const auto& line : lines) {
std::vector<StringPiece> fields =
SplitStringPiece(line, ":", TRIM_WHITESPACE, SPLIT_WANT_ALL);
if (fields.size() != 3U) {
if (fields[2] == kBackground)
return true;
return false;
#endif // defined(OS_CHROMEOS)
#if defined(OS_CHROMEOS)
// Reads /proc/<pid>/status and returns the PID in its PID namespace.
// If the process is not in a PID namespace or /proc/<pid>/status does not
// report NSpid, kNullProcessId is returned.
ProcessId Process::GetPidInNamespace() const {
std::string status;
// Synchronously reading files in /proc does not hit the disk.
ThreadRestrictions::ScopedAllowIO allow_io;
FilePath status_file =
if (!ReadFileToString(status_file, &status)) {
return kNullProcessId;
StringPairs pairs;
SplitStringIntoKeyValuePairs(status, ':', '\n', &pairs);
for (const auto& pair : pairs) {
const std::string& key = pair.first;
const std::string& value_str = pair.second;
if (key == "NSpid") {
std::vector<StringPiece> split_value_str = SplitStringPiece(
if (split_value_str.size() <= 1) {
return kNullProcessId;
int value;
// The last value in the list is the PID in the namespace.
if (!StringToInt(split_value_str.back(), &value)) {
return kNullProcessId;
return value;
return kNullProcessId;
#endif // defined(OS_CHROMEOS)
} // namespace base