bartoszek/zephyr
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

kernel: timeout: Reduce number of sys_clock_elapsed calls

Browse Source 
sys_clock_elapsed requires access to system clock register interface
which is often slow. When new relative timeout is added sys_clock_elapsed()
is called once to calculate delta ticks and then if that triggers setting
new timeout sys_clock_elapsed() is called again. This call is redundant
since everything happens under spin lock so it is better to reuse value
returned by the first call.

Signed-off-by: Krzysztof Chruściński <krzysztof.chruscinski@nordicsemi.no>
This commit is contained in:
Krzysztof Chruściński 2025-03-31 13:25:03 +02:00 committed by Benjamin Cabé
parent 83f877ae4b
commit e7d590568c
1 changed files with 16 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
kernel/timeout.c
View File

@ -84,10 +84,9 @@ static int32_t elapsed(void)
return announce_remaining == 0 ? sys_clock_elapsed() : 0U;
}
static int32_t next_timeout(void)
static int32_t next_timeout(int32_t ticks_elapsed)
{
struct _timeout *to = first();
int32_t ticks_elapsed = elapsed();
int32_t ret;
if ((to == NULL) ||
@ -116,9 +115,13 @@ void z_add_timeout(struct _timeout *to, _timeout_func_t fn,
K_SPINLOCK(&timeout_lock) {
struct _timeout *t;
int32_t ticks_elapsed;
bool has_elapsed = false;
if (Z_IS_TIMEOUT_RELATIVE(timeout)) {
to->dticks = timeout.ticks + 1 + elapsed();
ticks_elapsed = elapsed();
has_elapsed = true;
to->dticks = timeout.ticks + 1 + ticks_elapsed;
} else {
k_ticks_t ticks = Z_TICK_ABS(timeout.ticks) - curr_tick;
@ -139,7 +142,13 @@ void z_add_timeout(struct _timeout *to, _timeout_func_t fn,
}
if (to == first() && announce_remaining == 0) {
sys_clock_set_timeout(next_timeout(), false);
if (!has_elapsed) {
/* In case of absolute timeout that is first to expire
* elapsed need to be read from the system clock.
*/
ticks_elapsed = elapsed();
}
sys_clock_set_timeout(next_timeout(ticks_elapsed), false);
}
}
}
@ -155,7 +164,7 @@ int z_abort_timeout(struct _timeout *to)
remove_timeout(to);
ret = 0;
if (is_first) {
sys_clock_set_timeout(next_timeout(), false);
sys_clock_set_timeout(next_timeout(elapsed()), false);
}
}
}
@ -210,7 +219,7 @@ int32_t z_get_next_timeout_expiry(void)
int32_t ret = (int32_t) K_TICKS_FOREVER;
K_SPINLOCK(&timeout_lock) {
ret = next_timeout();
ret = next_timeout(elapsed());
}
return ret;
}
@ -257,7 +266,7 @@ void sys_clock_announce(int32_t ticks)
curr_tick += announce_remaining;
announce_remaining = 0;
sys_clock_set_timeout(next_timeout(), false);
sys_clock_set_timeout(next_timeout(0), false);
k_spin_unlock(&timeout_lock, key);