1 //
2 // Copyright (C) 2016 The Android Open Source Project
3 //
4 // Licensed under the Apache License, Version 2.0 (the "License");
5 // you may not use this file except in compliance with the License.
6 // You may obtain a copy of the License at
7 //
8 // http://www.apache.org/licenses/LICENSE-2.0
9 //
10 // Unless required by applicable law or agreed to in writing, software
11 // distributed under the License is distributed on an "AS IS" BASIS,
12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 // See the License for the specific language governing permissions and
14 // limitations under the License.
15 //
16
17 #include "update_engine/common/cpu_limiter.h"
18
19 #include <string>
20
21 #include <base/bind.h>
22 #include <base/logging.h>
23 #include <base/strings/string_number_conversions.h>
24 #include <base/time/time.h>
25
26 #include "update_engine/common/utils.h"
27
28 namespace {
29
30 // Cgroup container is created in update-engine's upstart script located at
31 // /etc/init/update-engine.conf.
32 const char kCGroupSharesPath[] = "/sys/fs/cgroup/cpu/update-engine/cpu.shares";
33
34 } // namespace
35
36 namespace chromeos_update_engine {
37
~CPULimiter()38 CPULimiter::~CPULimiter() {
39 // Set everything back to normal on destruction.
40 CPULimiter::SetCpuShares(CpuShares::kNormal);
41 }
42
StartLimiter()43 void CPULimiter::StartLimiter() {
44 if (manage_shares_id_ != brillo::MessageLoop::kTaskIdNull) {
45 LOG(ERROR) << "Cpu shares timeout source hasn't been destroyed.";
46 StopLimiter();
47 }
48 manage_shares_id_ = brillo::MessageLoop::current()->PostDelayedTask(
49 FROM_HERE,
50 base::Bind(&CPULimiter::StopLimiterCallback, base::Unretained(this)),
51 base::TimeDelta::FromHours(2));
52 SetCpuShares(CpuShares::kLow);
53 }
54
StopLimiter()55 void CPULimiter::StopLimiter() {
56 if (manage_shares_id_ != brillo::MessageLoop::kTaskIdNull) {
57 // If the shares were never set and there isn't a message loop instance,
58 // we avoid calling CancelTask(), which otherwise would have been a no-op.
59 brillo::MessageLoop::current()->CancelTask(manage_shares_id_);
60 manage_shares_id_ = brillo::MessageLoop::kTaskIdNull;
61 }
62 SetCpuShares(CpuShares::kNormal);
63 }
64
SetCpuShares(CpuShares shares)65 bool CPULimiter::SetCpuShares(CpuShares shares) {
66 // Short-circuit to avoid re-setting the shares.
67 if (shares_ == shares)
68 return true;
69
70 std::string string_shares = base::NumberToString(static_cast<int>(shares));
71 LOG(INFO) << "Setting cgroup cpu shares to " << string_shares;
72 if (!utils::WriteFile(
73 kCGroupSharesPath, string_shares.c_str(), string_shares.size())) {
74 LOG(ERROR) << "Failed to change cgroup cpu shares to " << string_shares
75 << " using " << kCGroupSharesPath;
76 return false;
77 }
78 shares_ = shares;
79 LOG(INFO) << "CPU shares = " << static_cast<int>(shares_);
80 return true;
81 }
82
StopLimiterCallback()83 void CPULimiter::StopLimiterCallback() {
84 SetCpuShares(CpuShares::kNormal);
85 manage_shares_id_ = brillo::MessageLoop::kTaskIdNull;
86 }
87
88 } // namespace chromeos_update_engine
89