bsd/sys/work_interval.h

   1 /*
   2  * Copyright (c) 2015-2017 Apple 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,
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  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_WORK_INTERVAL_H
  30 #define _SYS_WORK_INTERVAL_H
  31
  32 #include <stdint.h>
  33 #include <sys/cdefs.h>
  34 #include <sys/_types/_size_t.h>
  35
  36 #include <mach/port.h>
  37
  38 __BEGIN_DECLS
  39
  40 /*
  41  * A work interval is a repeatable unit of work characterized by a
  42  * start, finish, and deadline.
  43  *
  44  * Trusted clients with deadline-sensitive work may report information
  45  * about the execution of their work using the work interval facility.
  46  * This is intended to be a higher-level semantic than realtime scheduling,
  47  * which operates at the level of thread block/unblock. A high level
  48  * operation may have many blocking points, including IPC to other tasks,
  49  * and this this metric will capture the overall time to complete a unit of
  50  * work.
  51  *
  52  * A work interval is defined by several timestamps, namely (S)tart,
  53  * (F)inish, (D)eadline, and (N)ext start.
  54  *
  55  *   ... ----+==================+--------+--+==== ...
  56  *           |                  |        |  |
  57  *           S                  F        D  N
  58  *
  59  *           \__________________/
  60  *                  Active
  61  *           \___________________________/
  62  *                   Work Interval
  63  *
  64  *                               \_________/
  65  *                                    |
  66  *   report information here ---------+
  67  *
  68  * Definitions:
  69  *
  70  *   Start: Absolute time when the current deadline-oriented work began. Due
  71  *          to scheduling latency, preemption, and blocking points, the
  72  *          thread controlling the work interval may actually begin
  73  *          executing after this ideal time (which may be the previous work
  74  *          interval's "next start")
  75  *   Finish: Absolute time when the current deadline-oriented work finished.
  76  *          This will typically be a timestamp taken before reporting using
  77  *          the work interval interface.
  78  *   Deadline: Absolute time by which the current work was expected to finish.
  79  *          In cases where the amount of computation (or preemption, or time
  80  *          spent blocked) causes the active period to take longer than
  81  *          expected, F may be greater than D.
  82  *   Next start: Absolute time when the next deadline-oriented work is
  83  *          expected to begin. This is typically the same as Deadline.
  84  *   Active: The fraction of the work interval spent completing the work. In
  85  *          cases where the Finish time exceeded the Deadline, this fraction
  86  *          will be >1.0.
  87  *
  88  * Basic Use:
  89  *
  90  *   Clients should report information for a work interval after finishing
  91  *   work for the current interval but before the next work interval begins.
  92  *
  93  *   If Finish far exceeds the previously expected Deadline, the
  94  *   caller may adjust Next Start to align to a multiple of the period
  95  *   (and skip over several work intervals that could not be
  96  *   executed).
  97  *
  98  * Caution (!):
  99  *
 100  *   Because the information supplied via this facility directly influences power
 101  *   management decisions, clients should strive to be as accurate as possible.
 102  *   Failure to do so will adversely impact system power and performance.
 103  *
 104  * Work Interval Auto Join Support:
 105  *
 106  * Work intervals support an optional flag WORK_INTERVAL_FLAG_ENABLE_AUTO_JOIN
 107  * which allows RT threads from the same home thread group to join work
 108  * intervals via wakeup relationship tracking. Based on the join policy,
 109  * RT threads can temporarily join the work interval of other RT threads
 110  * which make them runnable. The auto joined thread remains in the work
 111  * interval until it blocks or terminates. The mechanism works through
 112  * make runnable heuristic and it should be used with extreme caution.
 113  * If a client specifies this flag, it gives up explicit control over its
 114  * thread group membership and threads unrelated to the work interval
 115  * could become part of the thread group. This could lead to serious power
 116  * and performance issues. If the make runnable heuristic does not work
 117  * for a client use case, it should adopt work_interval_join_port() or
 118  * work_interval_join() to explicitly declare its intent.
 119  *
 120  * Work Interval Deferred Finish Support:
 121  *
 122  * Another advanced feature for work intervals is the ability to defer the finish
 123  * calls for the work interval until all auto-joined threads for the work interval
 124  * have blocked or terminated. This feature is enabled via an optional flag
 125  * WORK_INTERVAL_FLAG_ENABLE_DEFERRED_FINISH and is valid only if the work interval
 126  * is configured with the WORK_INTERVAL_FLAG_ENABLE_AUTO_JOIN flag as well. The
 127  * deferred finish mechanism allows the work interval to defer the finish call
 128  * for the work interval until all auto-join threads have blocked/terminated
 129  * (and have therefore un-joined the work interval) or one of the work interval
 130  * threads calls start for the next frame. The deferred finish works only for
 131  * workloads that have no temporal overlap across frames i.e. previous frame has to
 132  * finish before next frame can start. This feature should be used with caution
 133  * since auto-joined threads would delay finish calls to the performance controller
 134  * which could lead to poor performance and battery life.
 135  */
 136
 137 /* Flags to be passed with work_interval_create() */
 138
 139 /* If interval is joinable, create no longer implicitly joins, you must use work_interval_join */
 140 #define WORK_INTERVAL_FLAG_JOINABLE                     (0x1)
 141 /* Only threads that join the group are measured together, otherwise the group is the creator's home group */
 142 #define WORK_INTERVAL_FLAG_GROUP                        (0x2)
 143 /* Specifies that the work interval is being created by a client who doesn't
 144  * necessarily have the PRIV_WORK_INTERVAL entitlement. Skip privilege checks.
 145  * This can only be masked in for work intervals of types COREAUDIO, CA_CLIENT
 146  * and DEFAULT */
 147 #define WORK_INTERVAL_FLAG_UNRESTRICTED                 (0x4)
 148
 149 /* [Advanced Flag] Read section on "Work Interval Auto Join Support" above for details */
 150 #define WORK_INTERVAL_FLAG_ENABLE_AUTO_JOIN             (0x8)
 151 /* [Advanced Flag] Read section on "Work Interval Deferred Finish Support" above for details */
 152 #define WORK_INTERVAL_FLAG_ENABLE_DEFERRED_FINISH       (0x10)
 153
 154 /* Kernel-supplied flag: Work interval has been ignored by the kernel */
 155 #define WORK_INTERVAL_FLAG_IGNORED                      (0x20)
 156
 157 /* Specifies that the work interval requests the system to provide just enough performance
 158  * to be able to finish at the provided deadline and no sooner. */
 159 #define WORK_INTERVAL_FLAG_FINISH_AT_DEADLINE           (0x40)
 160
 161 /* Flags to describe the interval flavor to the performance controller */
 162 #define WORK_INTERVAL_TYPE_MASK                 (0xF0000000)
 163 #define WORK_INTERVAL_TYPE_DEFAULT              (0x0 << 28)
 164 #define WORK_INTERVAL_TYPE_COREAUDIO            (0x1 << 28)
 165 #define WORK_INTERVAL_TYPE_COREANIMATION        (0x2 << 28)
 166 #define WORK_INTERVAL_TYPE_CA_RENDER_SERVER     (0x2 << 28)
 167 #define WORK_INTERVAL_TYPE_CA_CLIENT            (0x3 << 28)
 168 #define WORK_INTERVAL_TYPE_HID_DELIVERY         (0x4 << 28)
 169 #define WORK_INTERVAL_TYPE_COREMEDIA            (0x5 << 28)
 170 #define WORK_INTERVAL_TYPE_ARKIT                (0x6 << 28)
 171 #define WORK_INTERVAL_TYPE_LAST                 (0xF << 28)
 172
 173 #ifndef KERNEL
 174
 175 typedef struct work_interval *work_interval_t;
 176 typedef struct work_interval_instance *work_interval_instance_t;
 177
 178 /*
 179  * Create a new work interval handle.
 180  *
 181  * May fail with EALREADY if the current group already has a work interval.
 182  *
 183  * With no flags:
 184  *      Auto-joins the work interval to the creating thread
 185  *      May only use interval_handle from creating thread
 186  *      Data provided affects native thread group
 187  *
 188  * With the JOINABLE flag
 189  *      interval_handle is usable by the process
 190  *      creating thread does not auto-join
 191  *      notifying thread must have joined when notifying
 192  *
 193  * With the GROUP flag
 194  *      creates a new thread group to isolate the joined threads from
 195  *      the rest of the process for performance controller analysis
 196  *      Threads which join the work interval become members of this new group
 197  *
 198  * TODO: Add a name parameter so that clients can name the work interval
 199  * Can also take the thread name from the notifying thread
 200  *
 201  * Requires the 'com.apple.private.kernel.work-interval' entitlement (PRIV_WORK_INTERVAL)
 202  *
 203  * Note that joining a work interval supersedes automatic thread group management via vouchers
 204  */
 205 int     work_interval_create(work_interval_t *interval_handle, uint32_t flags);
 206
 207 /* Returns the flags used for the work interval when it was created.
 208  *
 209  * May fail with EINVAL if the port isn't from a prior call to
 210  * work_interval_copy_port.
 211  */
 212 int work_interval_get_flags_from_port(mach_port_t port, uint32_t *flags);
 213
 214
 215 /*
 216  * Notify the power management subsystem that the work for a current interval has completed
 217  *
 218  * Only the process which created the work interval may notify
 219  */
 220 int     work_interval_notify(work_interval_t    interval_handle,
 221     uint64_t start, uint64_t finish,
 222     uint64_t deadline, uint64_t next_start,
 223     uint32_t flags);
 224
 225 /*
 226  * Notify, with "finish" implicitly set to the current time
 227  *
 228  * Only the process which created the work interval may notify
 229  */
 230 int     work_interval_notify_simple(work_interval_t interval_handle,
 231     uint64_t start, uint64_t deadline,
 232     uint64_t next_start);
 233
 234 /*
 235  * Deallocate work interval handle
 236  * For non-JOINABLE, also removes thread from work interval
 237  * For JOINABLE, does not remove thread (needs a leave as well)
 238  */
 239 int     work_interval_destroy(work_interval_t interval_handle);
 240
 241 /*
 242  * Join work interval via work interval handle
 243  * Only allowed if interval is using the joinable and group flags
 244  *
 245  * Supersedes automatic thread group management via vouchers
 246  */
 247 int     work_interval_join(work_interval_t interval_handle);
 248
 249 /*
 250  * extract Mach send right representing work interval thread group
 251  * Returns a +1 send right ref, which must be deallocated via mach_port_deallocate
 252  * Only allowed if interval is joinable, otherwise returns ENOTSUP
 253  *
 254  * Supersedes automatic thread group management via vouchers
 255  */
 256 int     work_interval_copy_port(work_interval_t interval_handle, mach_port_t *port);
 257
 258 /*
 259  * Join work interval via Mach send right
 260  *
 261  * Does NOT consume Mach send right, must deallocate with mach_port_deallocate after using
 262  * It's safe to deallocate the right after joining, the thread will stay joined
 263  *
 264  * Can be sent to clients via xpc_dictionary_copy_mach_send, and similar
 265  *
 266  * Supersedes automatic thread group management via vouchers
 267  *
 268  * If the underlying work interval object is terminated then this may return ENOENT
 269  * <rdar://problem/31819320>
 270  */
 271 int     work_interval_join_port(mach_port_t port);
 272
 273 /*
 274  * Leave the current thread's work interval
 275  */
 276 int     work_interval_leave(void);
 277
 278 #endif /* !KERNEL */
 279
 280 #if PRIVATE
 281
 282 /* Private interface between Libsyscall and xnu */
 283 #define WORK_INTERVAL_OPERATION_CREATE  0x00000001      /* deprecated */
 284 #define WORK_INTERVAL_OPERATION_DESTROY 0x00000002      /* arg is NULL */
 285 #define WORK_INTERVAL_OPERATION_NOTIFY  0x00000003      /* arg is a work_interval_notification_t */
 286 #define WORK_INTERVAL_OPERATION_CREATE2 0x00000004      /* arg is a work_interval_create_params */
 287 #define WORK_INTERVAL_OPERATION_JOIN    0x00000005      /* arg is a port_name */
 288 #define WORK_INTERVAL_OPERATION_GET_FLAGS 0x00000009    /* arg is a port name */
 289
 290 struct work_interval_notification {
 291         uint64_t        start;
 292         uint64_t        finish;
 293         uint64_t        deadline;
 294         uint64_t        next_start;
 295         uint32_t        notify_flags;
 296         uint32_t        create_flags;
 297 };
 298 typedef struct work_interval_notification *work_interval_notification_t;
 299
 300 struct work_interval_create_params {
 301         uint64_t        wicp_id;          /* in/out param */
 302         mach_port_name_t wicp_port;       /* in/out param */
 303         uint32_t        wicp_create_flags;
 304 };
 305
 306
 307 int     __work_interval_ctl(uint32_t operation, uint64_t work_interval_id, void *arg, size_t len);
 308
 309 #endif /* PRIVATE */
 310
 311 __END_DECLS
 312
 313 #endif /* _SYS_WORK_INTERVAL_H */