1 /*
2  * Copyright (C) 2018 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 #ifndef __ANDROID_PSI_H__
18 #define __ANDROID_PSI_H__
19 
20 #include <sys/cdefs.h>
21 #include <sys/types.h>
22 
23 __BEGIN_DECLS
24 
25 enum psi_stall_type {
26     PSI_SOME,
27     PSI_FULL,
28     PSI_TYPE_COUNT
29 };
30 
31 /*
32  * Initializes psi monitor.
33  * stall_type, threshold_us and window_us are monitor parameters
34  * When successful, the function returns file descriptor that can
35  * be used with poll/epoll syscalls to wait for EPOLLPRI events.
36  * When unsuccessful, the function returns -1 and errno is set
37  * appropriately.
38  */
39 int init_psi_monitor(enum psi_stall_type stall_type,
40         int threshold_us, int window_us);
41 
42 /*
43  * Registers psi monitor file descriptor fd on the epoll instance
44  * referred to by the file descriptor epollfd.
45  * data parameter will be associated with event's epoll_data.ptr
46  * member.
47  */
48 int register_psi_monitor(int epollfd, int fd, void* data);
49 
50 /*
51  * Unregisters psi monitor file descriptor fd from the epoll instance
52  * referred to by the file descriptor epollfd.
53  */
54 int unregister_psi_monitor(int epollfd, int fd);
55 
56 /*
57  * Destroys psi monitor.
58  * fd is the file descriptor returned by psi monitor initialization
59  * routine.
60  * Note that if user process exits without calling this routine
61  * kernel will destroy the monitor as its lifetime is linked to
62  * the file descriptor.
63  */
64 void destroy_psi_monitor(int fd);
65 
66 __END_DECLS
67 
68 #endif  // __ANDROID_PSI_H__
69