/* * Copyright (c) 2013 Apple Computer, Inc. All rights reserved. * * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ * * This file contains Original Code and/or Modifications of Original Code * as defined in and that are subject to the Apple Public Source License * Version 2.0 (the 'License'). You may not use this file except in * compliance with the License. The rights granted to you under the License * may not be used to create, or enable the creation or redistribution of, * unlawful or unlicensed copies of an Apple operating system, or to * circumvent, violate, or enable the circumvention or violation of, any * terms of an Apple operating system software license agreement. * * Please obtain a copy of the License at * http://www.opensource.apple.com/apsl/ and read it before using this file. * * The Original Code and all software distributed under the License are * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. * Please see the License for the specific language governing rights and * limitations under the License. * * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ */ #ifndef _SYS_KERN_OVERRIDES_H #define _SYS_KERN_OVERRIDES_H #include <sys/cdefs.h> #include <sys/param.h> #include <sys/types.h> #include <stdint.h> __BEGIN_DECLS /* * system_override() system call * * The system_override() syscall is used to modify some kernel performance mechanisms. * The system call needs a special entitlement and should be used with extreme caution. * A misuse of this syscall could lead to severe performance and battery life issues. * * The caller needs to specify the mask for the specific mechanisms to modify and a * timeout. The implementation of this system call blocks the thread in the syscall * for the duration specified in the call. Blocking a thread in the system call allows * the kernel to revert the modification in case the calling process dies. It also * makes the change of behavior extremely obvious due to the backtrace of the calling * thread. * * Multiple agents are allowed to call this interface at the same time. The behavior * change is effective from the time the first call is made (for a specific mechanism) * until the longest timeout specified by any agent. If the caller wishes to disable * the behavior change caused by itself, it can call the same interface with the * SYS_OVERRIDE_DISABLE flag and the mechanism mask from another thread in the same * process. Note that this does not break out the original thread from the block * immediately. It simply undoes the mechanism change underneath. * * The currently supported overrides are: * - SYS_OVERRIDE_IO_THROTTLE: Modifies I/O throttling behavior * - SYS_OVERRIDE_CPU_THROTTLE: Modifies background stepper throttling mechanism * - SYS_OVERRIDE_FAST_JETSAM: Modifies jetsam behavior to use aggressive parallel jetsam * */ /* System Overrides Flags */ #define SYS_OVERRIDE_DISABLE (~(~0ull >> 1)) #define SYS_OVERRIDE_IO_THROTTLE 0x1 #define SYS_OVERRIDE_CPU_THROTTLE 0x2 #define SYS_OVERRIDE_FAST_JETSAM 0x4 #define SYS_OVERRIDE_FLAGS_MASK (SYS_OVERRIDE_DISABLE | SYS_OVERRIDE_IO_THROTTLE | SYS_OVERRIDE_CPU_THROTTLE | SYS_OVERRIDE_FAST_JETSAM) #ifdef BSD_KERNEL_PRIVATE void init_system_override(void); #endif #ifndef KERNEL int system_override(uint64_t timeout, uint64_t flags); #endif __END_DECLS #endif /*_SYS_KERN_OVERRIDES_H */