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kernel/arch: optimize memory use of some thread fields

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Some thread fields were 32-bit wide, when they are not even close to
using that full range of values. They are instead changed to 8-bit fields.

- prio can fit in one byte, limiting the priorities range to -128 to 127

- recursive scheduler locking can be limited to 255; a rollover results
  most probably from a logic error

- flags are split into execution flags and thread states; 8 bits is
  enough for each of them currently, with at worst two states and four
  flags to spare (on x86, on other archs, there are six flags to spare)

Doing this saves 8 bytes per stack. It also sets up an incoming
enhancement when checking if the current thread is preemptible on
interrupt exit.

Change-Id: Ieb5321a5b99f99173b0605dd4a193c3bc7ddabf4
Signed-off-by: Benjamin Walsh <benjamin.walsh@windriver.com>
This commit is contained in:
Benjamin Walsh 2016-12-21 15:38:54 -05:00 • committed by Anas Nashif
commit f955476559
22 changed files with 116 additions and 83 deletions
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28
kernel/include/ksched.h
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@ -271,25 +271,25 @@ static ALWAYS_INLINE void _sched_unlock_no_reschedule(void)
static inline void _set_thread_states(struct k_thread *thread, uint32_t states)
{
thread->base.flags |= states;
thread->base.thread_state |= states;
}
static inline void _reset_thread_states(struct k_thread *thread,
uint32_t states)
{
thread->base.flags &= ~states;
thread->base.thread_state &= ~states;
}
/* mark a thread as being suspended */
static inline void _mark_thread_as_suspended(struct k_thread *thread)
{
thread->base.flags |= K_SUSPENDED;
thread->base.thread_state |= K_SUSPENDED;
}
/* mark a thread as not being suspended */
static inline void _mark_thread_as_not_suspended(struct k_thread *thread)
{
thread->base.flags &= ~K_SUSPENDED;
thread->base.thread_state &= ~K_SUSPENDED;
}
static ALWAYS_INLINE int _is_thread_timeout_expired(struct k_thread *thread)
@ -313,14 +313,14 @@ static inline int _is_thread_timeout_active(struct k_thread *thread)
static inline int _has_thread_started(struct k_thread *thread)
{
return !(thread->base.flags & K_PRESTART);
return !(thread->base.thread_state & K_PRESTART);
}
static inline int _is_thread_prevented_from_running(struct k_thread *thread)
{
return thread->base.flags & (K_PENDING | K_PRESTART |
K_DEAD | K_DUMMY |
K_SUSPENDED);
return thread->base.thread_state & (K_PENDING | K_PRESTART |
K_DEAD | K_DUMMY |
K_SUSPENDED);
}
@ -334,19 +334,19 @@ static inline int _is_thread_ready(struct k_thread *thread)
/* mark a thread as pending in its TCS */
static inline void _mark_thread_as_pending(struct k_thread *thread)
{
thread->base.flags |= K_PENDING;
thread->base.thread_state |= K_PENDING;
}
/* mark a thread as not pending in its TCS */
static inline void _mark_thread_as_not_pending(struct k_thread *thread)
{
thread->base.flags &= ~K_PENDING;
thread->base.thread_state &= ~K_PENDING;
}
/* check if a thread is pending */
static inline int _is_thread_pending(struct k_thread *thread)
{
return !!(thread->base.flags & K_PENDING);
return !!(thread->base.thread_state & K_PENDING);
}
/**
@ -356,7 +356,7 @@ static inline int _is_thread_pending(struct k_thread *thread)
*/
static inline void _mark_thread_as_started(struct k_thread *thread)
{
thread->base.flags &= ~K_PRESTART;
thread->base.thread_state &= ~K_PRESTART;
}
/*
@ -394,7 +394,7 @@ static inline void _ready_thread(struct k_thread *thread)
*/
static inline void _mark_thread_as_dead(struct k_thread *thread)
{
thread->base.flags |= K_DEAD;
thread->base.thread_state |= K_DEAD;
}
/*
@ -463,7 +463,7 @@ static inline struct k_thread *_unpend_first_thread(_wait_q_t *wait_q)
/* must be called with interrupts locked */
static inline void _unpend_thread(struct k_thread *thread)
{
__ASSERT(thread->base.flags & K_PENDING, "");
__ASSERT(thread->base.thread_state & K_PENDING, "");
sys_dlist_remove(&thread->base.k_q_node);
_mark_thread_as_not_pending(thread);