Messages in this thread Patch in this message | | | From | Johannes Weiner <> | Subject | [PATCH] psi: clean up time collection functions | Date | Tue, 8 Jun 2021 15:04:52 -0400 |
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The functions to read the per-cpu time buckets and aggregate them don't have the greatest names and an awkward calling convention. Clean this up to make things a bit more readable:
- Rename get_recent_times() to read_cpu_states() to make it clearer this is about extracting psi state from one cpu, and not just the times, either. Remove the pchanged_states return parameter and make it the function's return value; rename the local variable 'states', as it doesn't reflect changed states, but currently active ones.
- rename collect_percpu_times() to aggregate_cpus(), to indicate that actual data processing happens there
- move calc_avgs() out of the way, closer to where it's being used.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> --- kernel/sched/psi.c | 90 ++++++++++++++++++++++------------------------ 1 file changed, 42 insertions(+), 48 deletions(-)
diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c index 9d647d974f55..1faf383f6ec4 100644 --- a/kernel/sched/psi.c +++ b/kernel/sched/psi.c @@ -238,17 +238,15 @@ static bool test_state(unsigned int *tasks, enum psi_states state) } } -static void get_recent_times(struct psi_group *group, int cpu, - enum psi_aggregators aggregator, u32 *times, - u32 *pchanged_states) +static u32 snapshot_cpu_states(struct psi_group *group, int cpu, + enum psi_aggregators aggregator, u32 *times) { struct psi_group_cpu *groupc = per_cpu_ptr(group->pcpu, cpu); u64 now, state_start; enum psi_states s; unsigned int seq; u32 state_mask; - - *pchanged_states = 0; + u32 states = 0; /* Snapshot a coherent view of the CPU state */ do { @@ -279,37 +277,18 @@ static void get_recent_times(struct psi_group *group, int cpu, times[s] = delta; if (delta) - *pchanged_states |= (1 << s); + states |= (1 << s); } -} -static void calc_avgs(unsigned long avg[3], int missed_periods, - u64 time, u64 period) -{ - unsigned long pct; - - /* Fill in zeroes for periods of no activity */ - if (missed_periods) { - avg[0] = calc_load_n(avg[0], EXP_10s, 0, missed_periods); - avg[1] = calc_load_n(avg[1], EXP_60s, 0, missed_periods); - avg[2] = calc_load_n(avg[2], EXP_300s, 0, missed_periods); - } - - /* Sample the most recent active period */ - pct = div_u64(time * 100, period); - pct *= FIXED_1; - avg[0] = calc_load(avg[0], EXP_10s, pct); - avg[1] = calc_load(avg[1], EXP_60s, pct); - avg[2] = calc_load(avg[2], EXP_300s, pct); + return states; } -static void collect_percpu_times(struct psi_group *group, - enum psi_aggregators aggregator, - u32 *pchanged_states) +static u32 aggregate_cpus(struct psi_group *group, + enum psi_aggregators aggregator) { u64 deltas[NR_PSI_STATES - 1] = { 0, }; unsigned long nonidle_total = 0; - u32 changed_states = 0; + u32 states = 0; int cpu; int s; @@ -324,11 +303,8 @@ static void collect_percpu_times(struct psi_group *group, for_each_possible_cpu(cpu) { u32 times[NR_PSI_STATES]; u32 nonidle; - u32 cpu_changed_states; - get_recent_times(group, cpu, aggregator, times, - &cpu_changed_states); - changed_states |= cpu_changed_states; + states |= snapshot_cpu_states(group, cpu, aggregator, times); nonidle = nsecs_to_jiffies(times[PSI_NONIDLE]); nonidle_total += nonidle; @@ -354,15 +330,34 @@ static void collect_percpu_times(struct psi_group *group, group->total[aggregator][s] += div_u64(deltas[s], max(nonidle_total, 1UL)); - if (pchanged_states) - *pchanged_states = changed_states; + return states; +} + +static void calc_avgs(unsigned long avg[3], int missed_periods, + u64 time, u64 period) +{ + unsigned long pct; + + /* Fill in zeroes for periods of no activity */ + if (missed_periods) { + avg[0] = calc_load_n(avg[0], EXP_10s, 0, missed_periods); + avg[1] = calc_load_n(avg[1], EXP_60s, 0, missed_periods); + avg[2] = calc_load_n(avg[2], EXP_300s, 0, missed_periods); + } + + /* Sample the most recent active period */ + pct = div_u64(time * 100, period); + pct *= FIXED_1; + avg[0] = calc_load(avg[0], EXP_10s, pct); + avg[1] = calc_load(avg[1], EXP_60s, pct); + avg[2] = calc_load(avg[2], EXP_300s, pct); } static void update_averages(struct psi_group *group) { unsigned long missed_periods = 0; u64 now, expires, period; - u32 changed_states; + u32 states; int s; /* avgX= */ @@ -402,7 +397,7 @@ static void update_averages(struct psi_group *group) group->avg_last_update = now; group->avg_next_update = expires + ((1 + missed_periods) * psi_period); - collect_percpu_times(group, PSI_AVGS, &changed_states); + states = aggregate_cpus(group, PSI_AVGS); for (s = 0; s < NR_PSI_STATES - 1; s++) { u32 sample; @@ -430,7 +425,7 @@ static void update_averages(struct psi_group *group) calc_avgs(group->avg[s], missed_periods, sample, period); } - if (changed_states & (1 << PSI_NONIDLE)) { + if (states & (1 << PSI_NONIDLE)) { unsigned long delay; delay = nsecs_to_jiffies(group->avg_next_update - now) + 1; @@ -585,24 +580,24 @@ static void psi_schedule_poll_work(struct psi_group *group, unsigned long delay) static void psi_poll_work(struct psi_group *group) { - u32 changed_states; + unsigned long delay; + u32 states; u64 now; mutex_lock(&group->trigger_lock); now = sched_clock(); + states = aggregate_cpus(group, PSI_POLL); - collect_percpu_times(group, PSI_POLL, &changed_states); - - if (changed_states & group->poll_states) { + if (states & group->poll_states) { /* Initialize trigger windows when entering polling mode */ if (now > group->polling_until) init_triggers(group, now); /* - * Keep the monitor active for at least the duration of the - * minimum tracking window as long as monitor states are - * changing. + * Keep the monitor active for at least the duration + * of the minimum tracking window after a polled state + * has been observed. */ group->polling_until = now + group->poll_min_period * UPDATES_PER_WINDOW; @@ -616,9 +611,8 @@ static void psi_poll_work(struct psi_group *group) if (now >= group->polling_next_update) group->polling_next_update = update_triggers(group, now); - psi_schedule_poll_work(group, - nsecs_to_jiffies(group->polling_next_update - now) + 1); - + delay = nsecs_to_jiffies(group->polling_next_update - now) + 1; + psi_schedule_poll_work(group, delay); out: mutex_unlock(&group->trigger_lock); } -- 2.32.0
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