64 lines
2.2 KiB
C
64 lines
2.2 KiB
C
/*
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* Copyright (c) 2018 Intel Corporation
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#ifndef ZEPHYR_INCLUDE_SCHED_PRIQ_H_
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#define ZEPHYR_INCLUDE_SCHED_PRIQ_H_
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#include <misc/util.h>
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#include <misc/dlist.h>
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#include <misc/rb.h>
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/* Two abstractions are defined here for "thread priority queues".
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*
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* One is a "dumb" list implementation appropriate for systems with
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* small numbers of threads and sensitive to code size. It is stored
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* in sorted order, taking an O(N) cost every time a thread is added
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* to the list. This corresponds to the way the original _wait_q_t
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* abstraction worked and is very fast as long as the number of
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* threads is small.
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*
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* The other is a balanced tree "fast" implementation with rather
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* larger code size (due to the data structure itself, the code here
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* is just stubs) and higher constant-factor performance overhead, but
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* much better O(logN) scaling in the presence of large number of
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* threads.
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*
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* Each can be used for either the wait_q or system ready queue,
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* configurable at build time.
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*/
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struct k_thread;
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struct k_thread *_priq_dumb_best(sys_dlist_t *pq);
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void _priq_dumb_remove(sys_dlist_t *pq, struct k_thread *thread);
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void _priq_dumb_add(sys_dlist_t *pq, struct k_thread *thread);
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struct _priq_rb {
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struct rbtree tree;
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int next_order_key;
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};
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void _priq_rb_add(struct _priq_rb *pq, struct k_thread *thread);
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void _priq_rb_remove(struct _priq_rb *pq, struct k_thread *thread);
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struct k_thread *_priq_rb_best(struct _priq_rb *pq);
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/* Traditional/textbook "multi-queue" structure. Separate lists for a
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* small number (max 32 here) of fixed priorities. This corresponds
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* to the original Zephyr scheduler. RAM requirements are
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* comparatively high, but performance is very fast. Won't work with
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* features like deadline scheduling which need large priority spaces
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* to represet their requirements.
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*/
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struct _priq_mq {
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sys_dlist_t queues[32];
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unsigned int bitmask; /* bit 1<<i set if queues[i] is non-empty */
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};
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void _priq_mq_add(struct _priq_mq *pq, struct k_thread *thread);
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void _priq_mq_remove(struct _priq_mq *pq, struct k_thread *thread);
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struct k_thread *_priq_mq_best(struct _priq_mq *pq);
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#endif /* ZEPHYR_INCLUDE_SCHED_PRIQ_H_ */
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