Enrico Fraccaroli (Galfurian)
72 lines
2.5 KiB
C
72 lines
2.5 KiB
C
/// @file prio.h
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/// @brief Defines processes priority value.
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/// @copyright (c) 2014-2022 This file is distributed under the MIT License.
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/// See LICENSE.md for details.
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// Priority of a process goes from 0..MAX_PRIO-1, valid RT
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// priority is 0..MAX_RT_PRIO-1, and SCHED_NORMAL/SCHED_BATCH
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// tasks are in the range MAX_RT_PRIO..MAX_PRIO-1. Priority
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// values are inverted: lower p->prio value means higher priority.
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//
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// The MAX_USER_RT_PRIO value allows the actual maximum
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// RT priority to be separate from the value exported to
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// user-space. This allows kernel threads to set their
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// priority to a value higher than any user task.
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// Note: MAX_RT_PRIO must not be smaller than MAX_USER_RT_PRIO.
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/// @brief Max niceness value.
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#define MAX_NICE +19
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/// @brief Min niceness value.
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#define MIN_NICE -20
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/// @brief Niceness range.
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#define NICE_WIDTH (MAX_NICE - MIN_NICE + 1)
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/// @brief Maximum real-time priority.
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#define MAX_RT_PRIO 100
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/// @brief Maximum priority.
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#define MAX_PRIO (MAX_RT_PRIO + NICE_WIDTH)
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/// @brief Default priority.
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#define DEFAULT_PRIO (MAX_RT_PRIO + NICE_WIDTH / 2)
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/// @brief Converts user-nice values [ -20 ... 0 ... 19 ]
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/// to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ].
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#define NICE_TO_PRIO(nice) ((nice) + DEFAULT_PRIO)
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/// @brief Converts static priority [ MAX_RT_PRIO..MAX_PRIO-1 ]
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/// to user-nice values [ -20 ... 0 ... 19 ].
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#define PRIO_TO_NICE(prio) ((prio)-DEFAULT_PRIO)
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/// @brief 'User priority' is the nice value converted to something we
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/// can work with better when scaling various scheduler parameters,
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/// it's a [ 0 ... 39 ] range.
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#define USER_PRIO(p) ((p)-MAX_RT_PRIO)
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/// @brief Provide easy access to the priority value of a task_struct.
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#define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio)
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/// @brief The maximum priority for a user process.
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#define MAX_USER_PRIO (USER_PRIO(MAX_PRIO))
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/// @brief Table that transforms the priority into a weight, used for
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/// computing the virtual runtime.
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static const int prio_to_weight[NICE_WIDTH] = {
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/* 100 */ 88761, 71755, 56483, 46273, 36291,
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/* 105 */ 29154, 23254, 18705, 14949, 11916,
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/* 110 */ 9548, 7620, 6100, 4904, 3906,
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/* 115 */ 3121, 2501, 1991, 1586, 1277,
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/* 120 */ 1024, 820, 655, 526, 423,
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/* 125 */ 335, 272, 215, 172, 137,
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/* 130 */ 110, 87, 70, 56, 45,
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/* 135 */ 36, 29, 23, 18, 15
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};
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/// @brief Transforms the priority to weight.
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#define GET_WEIGHT(prio) prio_to_weight[USER_PRIO((prio))]
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/// @brief Weight of a default priority.
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#define NICE_0_LOAD GET_WEIGHT(DEFAULT_PRIO)
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