--- /dev/null
+/*
+ * Copyright (c) 2015 Apple 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_WORK_INTERVAL_H
+#define _SYS_WORK_INTERVAL_H
+
+#include <stdint.h>
+#include <sys/types.h>
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+/*
+ * Trusted clients with deadline-sensitive work may report information
+ * about the execution of their work using the work interval facility.
+ * This is intended to be a higher-level semantic than realtime scheduling,
+ * which operates at the level of thread block/unblock. A high level
+ * operation may have many blocking points, including IPC to other tasks,
+ * and this this metric will capture the overall time to complete a unit of
+ * work.
+ *
+ * A work interval is defined by several timestamps, namely (S)tart,
+ * (F)inish, (D)eadline, and (N)ext start.
+ *
+ * ... ----+==================+--------+--+==== ...
+ * | | | |
+ * S F D N
+ *
+ * \__________________/
+ * Active
+ * \___________________________/
+ * Work Interval
+ *
+ * \_________/
+ * |
+ * report information here ---------+
+ *
+ * Definitions:
+ *
+ * Start: Absolute time when the current deadline-oriented work began. Due
+ * to scheduling latency, preemption, and blocking points, the
+ * thread controlling the work interval may actually begin
+ * executing after this ideal time (which may be the previous work
+ * interval's "next start")
+ * Finish: Absolute time when the current deadline-oriented work finished.
+ * This will typically be a timestamp taken before reporting using
+ * the work interval interface.
+ * Deadline: Absolute time by which the current work was expected to finish.
+ * In cases where the amount of computation (or preemption, or time
+ * spent blocked) causes the active period to take longer than
+ * expected, F may be greater than D.
+ * Next start: Absolute time when the next deadline-oriented work is
+ * expected to begin. This is typically the same as Deadline.
+ * Active: The fraction of the work interval spent completing the work. In
+ * cases where the Finish time exceeded the Deadline, this fraction
+ * will be >1.0.
+ *
+ * Basic Use:
+ *
+ * Clients should report information for a work interval after finishing
+ * work for the current interval but before the next work interval begins.
+ *
+ * If Finish far exceeds the previously expected Deadline, the
+ * caller may adjust Next Start to align to a multiple of the period
+ * (and skip over several work intervals that could not be
+ * executed).
+ *
+ * Caution (!):
+ *
+ * Because the information supplied via this facility directly influences power
+ * management decisions, clients should strive to be as accurate as possible.
+ * Failure to do so will adversely impact system power and performance.
+ *
+ */
+#ifndef KERNEL
+
+typedef struct work_interval *work_interval_t;
+
+/* Create a new work interval handle (currently for the current thread only). Flags is unused */
+int work_interval_create(work_interval_t *interval_handle, uint32_t flags);
+
+/* Notify the power management subsystem that the work for a current interval has completed */
+int work_interval_notify(work_interval_t interval_handle, uint64_t start, uint64_t finish, uint64_t deadline, uint64_t next_start, uint32_t flags);
+
+/* Notify, with "finish" implicitly set to the current time */
+int work_interval_notify_simple(work_interval_t interval_handle, uint64_t start, uint64_t deadline, uint64_t next_start);
+
+/* Deallocate work interval (currently for the current thread only) */
+int work_interval_destroy(work_interval_t interval_handle);
+
+#endif /* KERNEL */
+
+#if PRIVATE
+
+/* Private interface between Libsyscall and xnu */
+#define WORK_INTERVAL_OPERATION_CREATE 0x00000001 /* arg is a uint64_t * that accepts work interval ID as an OUT param */
+#define WORK_INTERVAL_OPERATION_DESTROY 0x00000002
+#define WORK_INTERVAL_OPERATION_NOTIFY 0x00000003 /* arg is a work_interval_notification_t */
+
+struct work_interval_notification {
+ uint64_t start;
+ uint64_t finish;
+ uint64_t deadline;
+ uint64_t next_start;
+ uint32_t flags;
+ uint32_t unused1;
+};
+typedef struct work_interval_notification *work_interval_notification_t;
+
+int __work_interval_ctl(uint32_t operation, uint64_t work_interval_id, void *arg, size_t len);
+
+#endif /* PRIVATE */
+
+__END_DECLS
+
+#endif /* _SYS_WORK_INTERVAL_H */
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