osfmk/mach/thread_policy.h

   1 /*
   2  * Copyright (c) 2000-2007 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,
  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 _MACH_THREAD_POLICY_H_
  30 #define _MACH_THREAD_POLICY_H_
  31
  32 #include <mach/mach_types.h>
  33
  34 /*
  35  * These are the calls for accessing the policy parameters
  36  * of a particular thread.
  37  *
  38  * The extra 'get_default' parameter to the second call is
  39  * IN/OUT as follows:
  40  * 1) if asserted on the way in it indicates that the default
  41  * values should be returned, not the ones currently set, in
  42  * this case 'get_default' will always be asserted on return;
  43  * 2) if unasserted on the way in, the current settings are
  44  * desired and if still unasserted on return, then the info
  45  * returned reflects the current settings, otherwise if
  46  * 'get_default' returns asserted, it means that there are no
  47  * current settings due to other parameters taking precedence,
  48  * and the default ones are being returned instead.
  49  */
  50
  51 typedef natural_t       thread_policy_flavor_t;
  52 typedef integer_t       *thread_policy_t;
  53
  54 /*
  55 kern_return_t   thread_policy_set(
  56                                         thread_t                                        thread,
  57                                         thread_policy_flavor_t          flavor,
  58                                         thread_policy_t                         policy_info,
  59                                         mach_msg_type_number_t          count);
  60
  61 kern_return_t   thread_policy_get(
  62                                         thread_t                                        thread,
  63                                         thread_policy_flavor_t          flavor,
  64                                         thread_policy_t                         policy_info,
  65                                         mach_msg_type_number_t          *count,
  66                                         boolean_t                                       *get_default);
  67 */
  68
  69 /*
  70  * Defined flavors.
  71  */
  72 /*
  73  * THREAD_STANDARD_POLICY:
  74  *
  75  * This is the standard (fair) scheduling mode, assigned to new
  76  * threads.  The thread will be given processor time in a manner
  77  * which apportions approximately equal share to long running
  78  * computations.
  79  *
  80  * Parameters:
  81  *      [none]
  82  */
  83
  84 #define THREAD_STANDARD_POLICY                  1
  85
  86 struct thread_standard_policy {
  87         natural_t               no_data;
  88 };
  89
  90 typedef struct thread_standard_policy   thread_standard_policy_data_t;
  91 typedef struct thread_standard_policy   *thread_standard_policy_t;
  92
  93 #define THREAD_STANDARD_POLICY_COUNT    0
  94
  95 /*
  96  * THREAD_EXTENDED_POLICY:
  97  *
  98  * Extended form of THREAD_STANDARD_POLICY, which supplies a
  99  * hint indicating whether this is a long running computation.
 100  *
 101  * Parameters:
 102  *
 103  * timeshare: TRUE (the default) results in identical scheduling
 104  * behavior as THREAD_STANDARD_POLICY.
 105  */
 106
 107 #define THREAD_EXTENDED_POLICY                  1
 108
 109 struct thread_extended_policy {
 110         boolean_t               timeshare;
 111 };
 112
 113 typedef struct thread_extended_policy   thread_extended_policy_data_t;
 114 typedef struct thread_extended_policy   *thread_extended_policy_t;
 115
 116 #define THREAD_EXTENDED_POLICY_COUNT    ((mach_msg_type_number_t) \
 117         (sizeof (thread_extended_policy_data_t) / sizeof (integer_t)))
 118
 119 /*
 120  * THREAD_TIME_CONSTRAINT_POLICY:
 121  *
 122  * This scheduling mode is for threads which have real time
 123  * constraints on their execution.
 124  *
 125  * Parameters:
 126  *
 127  * period: This is the nominal amount of time between separate
 128  * processing arrivals, specified in absolute time units.  A
 129  * value of 0 indicates that there is no inherent periodicity in
 130  * the computation.
 131  *
 132  * computation: This is the nominal amount of computation
 133  * time needed during a separate processing arrival, specified
 134  * in absolute time units.
 135  *
 136  * constraint: This is the maximum amount of real time that
 137  * may elapse from the start of a separate processing arrival
 138  * to the end of computation for logically correct functioning,
 139  * specified in absolute time units.  Must be (>= computation).
 140  * Note that latency = (constraint - computation).
 141  *
 142  * preemptible: This indicates that the computation may be
 143  * interrupted, subject to the constraint specified above.
 144  */
 145
 146 #define THREAD_TIME_CONSTRAINT_POLICY   2
 147
 148 struct thread_time_constraint_policy {
 149         uint32_t                period;
 150         uint32_t                computation;
 151         uint32_t                constraint;
 152         boolean_t               preemptible;
 153 };
 154
 155 typedef struct thread_time_constraint_policy    \
 156                                                                         thread_time_constraint_policy_data_t;
 157 typedef struct thread_time_constraint_policy    \
 158                                                                         *thread_time_constraint_policy_t;
 159
 160 #define THREAD_TIME_CONSTRAINT_POLICY_COUNT     ((mach_msg_type_number_t) \
 161         (sizeof (thread_time_constraint_policy_data_t) / sizeof (integer_t)))
 162
 163 /*
 164  * THREAD_PRECEDENCE_POLICY:
 165  *
 166  * This may be used to indicate the relative value of the
 167  * computation compared to the other threads in the task.
 168  *
 169  * Parameters:
 170  *
 171  * importance: The importance is specified as a signed value.
 172  */
 173
 174 #define THREAD_PRECEDENCE_POLICY                3
 175
 176 struct thread_precedence_policy {
 177         integer_t               importance;
 178 };
 179
 180 typedef struct thread_precedence_policy         thread_precedence_policy_data_t;
 181 typedef struct thread_precedence_policy         *thread_precedence_policy_t;
 182
 183 #define THREAD_PRECEDENCE_POLICY_COUNT  ((mach_msg_type_number_t) \
 184         (sizeof (thread_precedence_policy_data_t) / sizeof (integer_t)))
 185
 186 /*
 187  * THREAD_AFFINITY_POLICY:
 188  *
 189  * This policy is experimental.
 190  * This may be used to express affinity relationships
 191  * between threads in the task. Threads with the same affinity tag will
 192  * be scheduled to share an L2 cache if possible. That is, affinity tags
 193  * are a hint to the scheduler for thread placement.
 194  *
 195  * The namespace of affinity tags is generally local to one task. However,
 196  * a child task created after the assignment of affinity tags by its parent
 197  * will share that namespace. In particular, a family of forked processes
 198  * may be created with a shared affinity namespace.
 199  *
 200  * Parameters:
 201  * tag: The affinity set identifier.
 202  */
 203
 204 #define THREAD_AFFINITY_POLICY          4
 205
 206 struct thread_affinity_policy {
 207         integer_t       affinity_tag;
 208 };
 209
 210 #define THREAD_AFFINITY_TAG_NULL                0
 211
 212 typedef struct thread_affinity_policy           thread_affinity_policy_data_t;
 213 typedef struct thread_affinity_policy           *thread_affinity_policy_t;
 214
 215 #define THREAD_AFFINITY_POLICY_COUNT    ((mach_msg_type_number_t) \
 216         (sizeof (thread_affinity_policy_data_t) / sizeof (integer_t)))
 217
 218 /*
 219  * THREAD_BACKGROUND_POLICY:
 220  */
 221
 222 #define THREAD_BACKGROUND_POLICY        5
 223
 224 struct thread_background_policy {
 225         integer_t       priority;
 226 };
 227
 228 typedef struct thread_background_policy         thread_background_policy_data_t;
 229 typedef struct thread_background_policy         *thread_background_policy_t;
 230
 231 #define THREAD_BACKGROUND_POLICY_COUNT  ((mach_msg_type_number_t) \
 232         (sizeof (thread_background_policy_data_t) / sizeof (integer_t)))
 233
 234
 235 #define THREAD_LATENCY_QOS_POLICY       7
 236 typedef integer_t       thread_latency_qos_t;
 237
 238 struct thread_latency_qos_policy {
 239         thread_latency_qos_t thread_latency_qos_tier;
 240 };
 241
 242 typedef struct thread_latency_qos_policy        thread_latency_qos_policy_data_t;
 243 typedef struct thread_latency_qos_policy        *thread_latency_qos_policy_t;
 244
 245 #define THREAD_LATENCY_QOS_POLICY_COUNT ((mach_msg_type_number_t)       \
 246             (sizeof (thread_latency_qos_policy_data_t) / sizeof (integer_t)))
 247
 248 #define THREAD_THROUGHPUT_QOS_POLICY    8
 249 typedef integer_t       thread_throughput_qos_t;
 250
 251 struct thread_throughput_qos_policy {
 252         thread_throughput_qos_t thread_throughput_qos_tier;
 253 };
 254
 255 typedef struct thread_throughput_qos_policy     thread_throughput_qos_policy_data_t;
 256 typedef struct thread_throughput_qos_policy     *thread_throughput_qos_policy_t;
 257
 258 #define THREAD_THROUGHPUT_QOS_POLICY_COUNT      ((mach_msg_type_number_t) \
 259             (sizeof (thread_throughput_qos_policy_data_t) / sizeof (integer_t)))
 260
 261 #ifdef PRIVATE
 262
 263 /*
 264  * THREAD_POLICY_STATE:
 265  */
 266 #define THREAD_POLICY_STATE             6
 267
 268 #define THREAD_POLICY_STATE_FLAG_STATIC_PARAM   0x1
 269
 270 struct thread_policy_state {
 271         integer_t requested;
 272         integer_t effective;
 273         integer_t pending;
 274         integer_t flags;
 275         integer_t reserved[12];
 276 };
 277
 278 typedef struct thread_policy_state              thread_policy_state_data_t;
 279 typedef struct thread_policy_state              *thread_policy_state_t;
 280
 281 #define THREAD_POLICY_STATE_COUNT       ((mach_msg_type_number_t) \
 282         (sizeof (thread_policy_state_data_t) / sizeof (integer_t)))
 283
 284 /*
 285  * THREAD_QOS_POLICY:
 286  */
 287 #define THREAD_QOS_POLICY               9
 288 #define THREAD_QOS_POLICY_OVERRIDE      10
 289
 290 #define THREAD_QOS_UNSPECIFIED          0
 291 #define THREAD_QOS_DEFAULT              THREAD_QOS_UNSPECIFIED  /* Temporary rename */
 292 #define THREAD_QOS_MAINTENANCE          1
 293 #define THREAD_QOS_BACKGROUND           2
 294 #define THREAD_QOS_UTILITY              3
 295 #define THREAD_QOS_LEGACY               4       /* i.e. default workq threads */
 296 #define THREAD_QOS_USER_INITIATED       5
 297 #define THREAD_QOS_USER_INTERACTIVE     6
 298
 299 #define THREAD_QOS_LAST                 7
 300
 301 #define THREAD_QOS_MIN_TIER_IMPORTANCE  (-15)
 302
 303 /*
 304  * Overrides are inputs to the task/thread policy engine that
 305  * temporarily elevate the effective QoS of a thread without changing
 306  * its steady-state (and round-trip-able) requested QoS. The
 307  * interfaces into the kernel allow the caller to associate a resource
 308  * and type that describe the reason/lifecycle of the override. For
 309  * instance, a contended pthread_mutex_t held by a UTILITY thread
 310  * might get an override to USER_INTERACTIVE, with the resource
 311  * being the userspace address of the pthread_mutex_t. When the
 312  * owning thread releases that resource, it can call into the
 313  * task policy subsystem to drop the override because of that resource,
 314  * although if more contended locks are held by the thread, the
 315  * effective QoS may remain overridden for longer.
 316  *
 317  * THREAD_QOS_OVERRIDE_TYPE_PTHREAD_MUTEX is used for contended
 318  * pthread_mutex_t's via the pthread kext. The holder gets an override
 319  * with resource=&mutex and a count of 1 by the initial contender.
 320  * Subsequent contenders raise the QoS value, until the holder
 321  * decrements the count to 0 and the override is released.
 322  *
 323  * THREAD_QOS_OVERRIDE_TYPE_PTHREAD_RWLOCK is unimplemented and has no
 324  * specified semantics.
 325  *
 326  * THREAD_QOS_OVERRIDE_TYPE_PTHREAD_EXPLICIT_OVERRIDE are explicitly
 327  * paired start/end overrides on a target thread. The resource can
 328  * either be a memory allocation in userspace, or the pthread_t of the
 329  * overrider if no allocation was used.
 330  *
 331  * THREAD_QOS_OVERRIDE_TYPE_DISPATCH_ASYNCHRONOUS_OVERRIDE are used to
 332  * override the QoS of a thread currently draining a serial dispatch
 333  * queue, so that it can get to a block of higher QoS than its
 334  * predecessors. The override is applied by a thread enqueueing work
 335  * with resource=&queue, and reset by the thread that was overriden
 336  * once it has drained the queue. Since the ++ and reset are
 337  * asynchronous, there is the possibility of a ++ after the target
 338  * thread has issued a reset, in which case the workqueue thread may
 339  * issue a reset-all in its outermost scope before deciding whether it
 340  * should return to dequeueing work from the global concurrent queues,
 341  * or return to the kernel.
 342  */
 343
 344 #define THREAD_QOS_OVERRIDE_TYPE_UNKNOWN                                        (0)
 345 #define THREAD_QOS_OVERRIDE_TYPE_PTHREAD_MUTEX                          (1)
 346 #define THREAD_QOS_OVERRIDE_TYPE_PTHREAD_RWLOCK                         (2)
 347 #define THREAD_QOS_OVERRIDE_TYPE_PTHREAD_EXPLICIT_OVERRIDE      (3)
 348 #define THREAD_QOS_OVERRIDE_TYPE_DISPATCH_ASYNCHRONOUS_OVERRIDE (4)
 349
 350 /* A special resource value to indicate a resource wildcard */
 351 #define THREAD_QOS_OVERRIDE_RESOURCE_WILDCARD (~((user_addr_t)0))
 352
 353 struct thread_qos_policy {
 354         integer_t qos_tier;
 355         integer_t tier_importance;
 356 };
 357
 358 typedef struct thread_qos_policy       thread_qos_policy_data_t;
 359 typedef struct thread_qos_policy      *thread_qos_policy_t;
 360
 361 #define THREAD_QOS_POLICY_COUNT    ((mach_msg_type_number_t) \
 362         (sizeof (thread_qos_policy_data_t) / sizeof (integer_t)))
 363
 364 #endif /* PRIVATE */
 365
 366 #endif  /* _MACH_THREAD_POLICY_H_ */