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1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #include "base/process.h" | |
6 | |
7 #include <errno.h> | |
8 #include <sys/resource.h> | |
9 | |
10 #include "base/file_util.h" | |
11 #include "base/lazy_instance.h" | |
12 #include "base/logging.h" | |
13 #include "base/strings/string_split.h" | |
14 #include "base/strings/stringprintf.h" | |
15 #include "base/synchronization/lock.h" | |
16 | |
17 namespace { | |
18 const int kForegroundPriority = 0; | |
19 | |
20 #if defined(OS_CHROMEOS) | |
21 // We are more aggressive in our lowering of background process priority | |
22 // for chromeos as we have much more control over other processes running | |
23 // on the machine. | |
24 // | |
25 // TODO(davemoore) Refactor this by adding support for higher levels to set | |
26 // the foregrounding / backgrounding process so we don't have to keep | |
27 // chrome / chromeos specific logic here. | |
28 const int kBackgroundPriority = 19; | |
29 const char kControlPath[] = "/sys/fs/cgroup/cpu%s/cgroup.procs"; | |
30 const char kForeground[] = "/chrome_renderers/foreground"; | |
31 const char kBackground[] = "/chrome_renderers/background"; | |
32 const char kProcPath[] = "/proc/%d/cgroup"; | |
33 | |
34 struct CGroups { | |
35 // Check for cgroups files. ChromeOS supports these by default. It creates | |
36 // a cgroup mount in /sys/fs/cgroup and then configures two cpu task groups, | |
37 // one contains at most a single foreground renderer and the other contains | |
38 // all background renderers. This allows us to limit the impact of background | |
39 // renderers on foreground ones to a greater level than simple renicing. | |
40 bool enabled; | |
41 base::FilePath foreground_file; | |
42 base::FilePath background_file; | |
43 | |
44 CGroups() { | |
45 foreground_file = | |
46 base::FilePath(base::StringPrintf(kControlPath, kForeground)); | |
47 background_file = | |
48 base::FilePath(base::StringPrintf(kControlPath, kBackground)); | |
49 file_util::FileSystemType foreground_type; | |
50 file_util::FileSystemType background_type; | |
51 enabled = | |
52 file_util::GetFileSystemType(foreground_file, &foreground_type) && | |
53 file_util::GetFileSystemType(background_file, &background_type) && | |
54 foreground_type == file_util::FILE_SYSTEM_CGROUP && | |
55 background_type == file_util::FILE_SYSTEM_CGROUP; | |
56 } | |
57 }; | |
58 | |
59 base::LazyInstance<CGroups> cgroups = LAZY_INSTANCE_INITIALIZER; | |
60 #else | |
61 const int kBackgroundPriority = 5; | |
62 #endif | |
63 } | |
64 | |
65 namespace base { | |
66 | |
67 bool Process::IsProcessBackgrounded() const { | |
68 DCHECK(process_); | |
69 | |
70 #if defined(OS_CHROMEOS) | |
71 if (cgroups.Get().enabled) { | |
72 std::string proc; | |
73 if (file_util::ReadFileToString( | |
74 base::FilePath(StringPrintf(kProcPath, process_)), | |
75 &proc)) { | |
76 std::vector<std::string> proc_parts; | |
77 base::SplitString(proc, ':', &proc_parts); | |
78 DCHECK(proc_parts.size() == 3); | |
79 bool ret = proc_parts[2] == std::string(kBackground); | |
80 return ret; | |
81 } else { | |
82 return false; | |
83 } | |
84 } | |
85 #endif | |
86 return GetPriority() == kBackgroundPriority; | |
87 } | |
88 | |
89 bool Process::SetProcessBackgrounded(bool background) { | |
90 DCHECK(process_); | |
91 | |
92 #if defined(OS_CHROMEOS) | |
93 if (cgroups.Get().enabled) { | |
94 std::string pid = StringPrintf("%d", process_); | |
95 const base::FilePath file = | |
96 background ? | |
97 cgroups.Get().background_file : cgroups.Get().foreground_file; | |
98 return file_util::WriteFile(file, pid.c_str(), pid.size()) > 0; | |
99 } | |
100 #endif // OS_CHROMEOS | |
101 | |
102 if (!CanBackgroundProcesses()) | |
103 return false; | |
104 | |
105 int priority = background ? kBackgroundPriority : kForegroundPriority; | |
106 int result = setpriority(PRIO_PROCESS, process_, priority); | |
107 DPCHECK(result == 0); | |
108 return result == 0; | |
109 } | |
110 | |
111 struct CheckForNicePermission { | |
112 CheckForNicePermission() : can_reraise_priority(false) { | |
113 // We won't be able to raise the priority if we don't have the right rlimit. | |
114 // The limit may be adjusted in /etc/security/limits.conf for PAM systems. | |
115 struct rlimit rlim; | |
116 if ((getrlimit(RLIMIT_NICE, &rlim) == 0) && | |
117 (20 - kForegroundPriority) <= static_cast<int>(rlim.rlim_cur)) { | |
118 can_reraise_priority = true; | |
119 } | |
120 }; | |
121 | |
122 bool can_reraise_priority; | |
123 }; | |
124 | |
125 // static | |
126 bool Process::CanBackgroundProcesses() { | |
127 #if defined(OS_CHROMEOS) | |
128 if (cgroups.Get().enabled) | |
129 return true; | |
130 #endif | |
131 | |
132 static LazyInstance<CheckForNicePermission> check_for_nice_permission = | |
133 LAZY_INSTANCE_INITIALIZER; | |
134 return check_for_nice_permission.Get().can_reraise_priority; | |
135 } | |
136 | |
137 } // namespace base | |
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