1 | /* |
2 | * Copyright (c) 2013 Apple Computer, Inc. All rights reserved. |
3 | * |
4 | * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ |
5 | * |
6 | * This file contains Original Code and/or Modifications of Original Code |
7 | * as defined in and that are subject to the Apple Public Source License |
8 | * Version 2.0 (the 'License'). You may not use this file except in |
9 | * compliance with the License. The rights granted to you under the License |
10 | * may not be used to create, or enable the creation or redistribution of, |
11 | * unlawful or unlicensed copies of an Apple operating system, or to |
12 | * circumvent, violate, or enable the circumvention or violation of, any |
13 | * terms of an Apple operating system software license agreement. |
14 | * |
15 | * Please obtain a copy of the License at |
16 | * http://www.opensource.apple.com/apsl/ and read it before using this file. |
17 | * |
18 | * The Original Code and all software distributed under the License are |
19 | * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER |
20 | * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, |
21 | * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, |
22 | * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. |
23 | * Please see the License for the specific language governing rights and |
24 | * limitations under the License. |
25 | * |
26 | * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ |
27 | */ |
28 | |
29 | #ifndef _SYS_KERN_OVERRIDES_H |
30 | #define _SYS_KERN_OVERRIDES_H |
31 | |
32 | #include <sys/cdefs.h> |
33 | #include <sys/param.h> |
34 | #include <sys/types.h> |
35 | #include <stdint.h> |
36 | |
37 | __BEGIN_DECLS |
38 | |
39 | /* |
40 | * system_override() system call |
41 | * |
42 | * The system_override() syscall is used to modify some kernel performance mechanisms. |
43 | * The system call needs a special entitlement and should be used with extreme caution. |
44 | * A misuse of this syscall could lead to severe performance and battery life issues. |
45 | * |
46 | * The caller needs to specify the mask for the specific mechanisms to modify and a |
47 | * timeout. The implementation of this system call blocks the thread in the syscall |
48 | * for the duration specified in the call. Blocking a thread in the system call allows |
49 | * the kernel to revert the modification in case the calling process dies. It also |
50 | * makes the change of behavior extremely obvious due to the backtrace of the calling |
51 | * thread. |
52 | * |
53 | * Multiple agents are allowed to call this interface at the same time. The behavior |
54 | * change is effective from the time the first call is made (for a specific mechanism) |
55 | * until the longest timeout specified by any agent. If the caller wishes to disable |
56 | * the behavior change caused by itself, it can call the same interface with the |
57 | * SYS_OVERRIDE_DISABLE flag and the mechanism mask from another thread in the same |
58 | * process. Note that this does not break out the original thread from the block |
59 | * immediately. It simply undoes the mechanism change underneath. |
60 | * |
61 | * The currently supported overrides are: |
62 | * - SYS_OVERRIDE_IO_THROTTLE: Modifies I/O throttling behavior |
63 | * - SYS_OVERRIDE_CPU_THROTTLE: Modifies background stepper throttling mechanism |
64 | * - SYS_OVERRIDE_FAST_JETSAM: Modifies jetsam behavior to use aggressive parallel jetsam |
65 | * |
66 | */ |
67 | |
68 | /* System Overrides Flags */ |
69 | #define SYS_OVERRIDE_DISABLE (~(~0ull >> 1)) |
70 | #define SYS_OVERRIDE_IO_THROTTLE 0x1 |
71 | #define SYS_OVERRIDE_CPU_THROTTLE 0x2 |
72 | #define SYS_OVERRIDE_FAST_JETSAM 0x4 |
73 | |
74 | #define SYS_OVERRIDE_FLAGS_MASK (SYS_OVERRIDE_DISABLE | SYS_OVERRIDE_IO_THROTTLE | SYS_OVERRIDE_CPU_THROTTLE | SYS_OVERRIDE_FAST_JETSAM) |
75 | |
76 | #ifdef BSD_KERNEL_PRIVATE |
77 | void init_system_override(void); |
78 | #endif |
79 | |
80 | #ifndef KERNEL |
81 | int system_override(uint64_t timeout, uint64_t flags); |
82 | #endif |
83 | |
84 | __END_DECLS |
85 | |
86 | #endif /*_SYS_KERN_OVERRIDES_H */ |
87 | |