3e696896bf
Zephyr's timeslice implementation has always been somewhat primitive. You get a global timeslice that applies broadly to the whole bottom of the priority space, with no ability (beyond that one priority threshold) to tune it to work on certain threads, etc... This adds an (optionally configurable) API that allows timeslicing to be controlled on a per-thread basis: any thread at any priority can be set to timeslice, for a configurable per-thread slice time, and at the end of its slice a callback can be provided that can take action. This allows the application to implement things like responsiveness heuristics, "fair" scheduling algorithms, etc... without requiring that facility in the core kernel. Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
255 lines
5.7 KiB
C
255 lines
5.7 KiB
C
/*
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* Copyright (c) 2016 Wind River Systems, Inc.
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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/*
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* The purpose of this file is to provide essential/minimal kernel structure
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* definitions, so that they can be used without including kernel.h.
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*
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* The following rules must be observed:
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* 1. kernel_structs.h shall not depend on kernel.h both directly and
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* indirectly (i.e. it shall not include any header files that include
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* kernel.h in their dependency chain).
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* 2. kernel.h shall imply kernel_structs.h, such that it shall not be
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* necessary to include kernel_structs.h explicitly when kernel.h is
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* included.
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*/
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#ifndef ZEPHYR_KERNEL_INCLUDE_KERNEL_STRUCTS_H_
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#define ZEPHYR_KERNEL_INCLUDE_KERNEL_STRUCTS_H_
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#if !defined(_ASMLANGUAGE)
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#include <sys/atomic.h>
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#include <zephyr/types.h>
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#include <kernel/sched_priq.h>
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#include <sys/dlist.h>
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#include <sys/util.h>
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#include <sys/sys_heap.h>
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#include <arch/structs.h>
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#include <kernel/stats.h>
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#endif
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#ifdef __cplusplus
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extern "C" {
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#endif
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/*
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* Bitmask definitions for the struct k_thread.thread_state field.
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*
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* Must be before kerneL_arch_data.h because it might need them to be already
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* defined.
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*/
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/* states: common uses low bits, arch-specific use high bits */
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/* Not a real thread */
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#define _THREAD_DUMMY (BIT(0))
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/* Thread is waiting on an object */
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#define _THREAD_PENDING (BIT(1))
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/* Thread has not yet started */
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#define _THREAD_PRESTART (BIT(2))
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/* Thread has terminated */
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#define _THREAD_DEAD (BIT(3))
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/* Thread is suspended */
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#define _THREAD_SUSPENDED (BIT(4))
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/* Thread is being aborted */
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#define _THREAD_ABORTING (BIT(5))
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/* Thread is present in the ready queue */
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#define _THREAD_QUEUED (BIT(7))
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/* end - states */
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#ifdef CONFIG_STACK_SENTINEL
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/* Magic value in lowest bytes of the stack */
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#define STACK_SENTINEL 0xF0F0F0F0
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#endif
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/* lowest value of _thread_base.preempt at which a thread is non-preemptible */
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#define _NON_PREEMPT_THRESHOLD 0x0080U
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/* highest value of _thread_base.preempt at which a thread is preemptible */
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#define _PREEMPT_THRESHOLD (_NON_PREEMPT_THRESHOLD - 1U)
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#if !defined(_ASMLANGUAGE)
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struct _ready_q {
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#ifndef CONFIG_SMP
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/* always contains next thread to run: cannot be NULL */
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struct k_thread *cache;
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#endif
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#if defined(CONFIG_SCHED_DUMB)
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sys_dlist_t runq;
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#elif defined(CONFIG_SCHED_SCALABLE)
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struct _priq_rb runq;
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#elif defined(CONFIG_SCHED_MULTIQ)
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struct _priq_mq runq;
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#endif
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};
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typedef struct _ready_q _ready_q_t;
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struct _cpu {
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/* nested interrupt count */
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uint32_t nested;
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/* interrupt stack pointer base */
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char *irq_stack;
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/* currently scheduled thread */
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struct k_thread *current;
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/* one assigned idle thread per CPU */
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struct k_thread *idle_thread;
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#ifdef CONFIG_SCHED_CPU_MASK_PIN_ONLY
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struct _ready_q ready_q;
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#endif
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#if (CONFIG_NUM_METAIRQ_PRIORITIES > 0) && (CONFIG_NUM_COOP_PRIORITIES > 0)
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/* Coop thread preempted by current metairq, or NULL */
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struct k_thread *metairq_preempted;
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#endif
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#ifdef CONFIG_TIMESLICING
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/* number of ticks remaining in current time slice */
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int slice_ticks;
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#endif
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uint8_t id;
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#ifdef CONFIG_SMP
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/* True when _current is allowed to context switch */
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uint8_t swap_ok;
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#endif
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#ifdef CONFIG_SCHED_THREAD_USAGE
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/*
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* [usage0] is used as a timestamp to mark the beginning of an
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* execution window. [0] is a special value indicating that it
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* has been stopped (but not disabled).
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*/
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uint32_t usage0;
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#ifdef CONFIG_SCHED_THREAD_USAGE_ALL
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struct k_cycle_stats usage;
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#endif
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#endif
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/* Per CPU architecture specifics */
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struct _cpu_arch arch;
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};
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typedef struct _cpu _cpu_t;
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struct z_kernel {
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struct _cpu cpus[CONFIG_MP_NUM_CPUS];
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#ifdef CONFIG_PM
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int32_t idle; /* Number of ticks for kernel idling */
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#endif
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/*
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* ready queue: can be big, keep after small fields, since some
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* assembly (e.g. ARC) are limited in the encoding of the offset
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*/
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#ifndef CONFIG_SCHED_CPU_MASK_PIN_ONLY
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struct _ready_q ready_q;
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#endif
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#ifdef CONFIG_FPU_SHARING
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/*
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* A 'current_sse' field does not exist in addition to the 'current_fp'
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* field since it's not possible to divide the IA-32 non-integer
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* registers into 2 distinct blocks owned by differing threads. In
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* other words, given that the 'fxnsave/fxrstor' instructions
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* save/restore both the X87 FPU and XMM registers, it's not possible
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* for a thread to only "own" the XMM registers.
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*/
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/* thread that owns the FP regs */
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struct k_thread *current_fp;
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#endif
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#if defined(CONFIG_THREAD_MONITOR)
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struct k_thread *threads; /* singly linked list of ALL threads */
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#endif
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};
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typedef struct z_kernel _kernel_t;
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extern struct z_kernel _kernel;
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#ifdef CONFIG_SMP
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/* True if the current context can be preempted and migrated to
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* another SMP CPU.
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*/
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bool z_smp_cpu_mobile(void);
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#define _current_cpu ({ __ASSERT_NO_MSG(!z_smp_cpu_mobile()); \
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arch_curr_cpu(); })
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#define _current z_current_get()
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#else
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#define _current_cpu (&_kernel.cpus[0])
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#define _current _kernel.cpus[0].current
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#endif
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/* kernel wait queue record */
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#ifdef CONFIG_WAITQ_SCALABLE
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typedef struct {
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struct _priq_rb waitq;
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} _wait_q_t;
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extern bool z_priq_rb_lessthan(struct rbnode *a, struct rbnode *b);
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#define Z_WAIT_Q_INIT(wait_q) { { { .lessthan_fn = z_priq_rb_lessthan } } }
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#else
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typedef struct {
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sys_dlist_t waitq;
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} _wait_q_t;
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#define Z_WAIT_Q_INIT(wait_q) { SYS_DLIST_STATIC_INIT(&(wait_q)->waitq) }
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#endif
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/* kernel timeout record */
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struct _timeout;
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typedef void (*_timeout_func_t)(struct _timeout *t);
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struct _timeout {
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sys_dnode_t node;
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_timeout_func_t fn;
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#ifdef CONFIG_TIMEOUT_64BIT
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/* Can't use k_ticks_t for header dependency reasons */
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int64_t dticks;
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#else
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int32_t dticks;
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#endif
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};
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typedef void (*k_thread_timeslice_fn_t)(struct k_thread *thread, void *data);
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#ifdef __cplusplus
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}
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#endif
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#endif /* _ASMLANGUAGE */
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#endif /* ZEPHYR_KERNEL_INCLUDE_KERNEL_STRUCTS_H_ */
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