diff options
Diffstat (limited to 'kernel/sched/walt.c')
| -rw-r--r-- | kernel/sched/walt.c | 1171 |
1 files changed, 1171 insertions, 0 deletions
diff --git a/kernel/sched/walt.c b/kernel/sched/walt.c new file mode 100644 index 000000000000..07b7f84b37e2 --- /dev/null +++ b/kernel/sched/walt.c @@ -0,0 +1,1171 @@ +/* + * Copyright (c) 2016, The Linux Foundation. All rights reserved. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 and + * only version 2 as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * + * Window Assisted Load Tracking (WALT) implementation credits: + * Srivatsa Vaddagiri, Steve Muckle, Syed Rameez Mustafa, Joonwoo Park, + * Pavan Kumar Kondeti, Olav Haugan + * + * 2016-03-06: Integration with EAS/refactoring by Vikram Mulukutla + * and Todd Kjos + */ + +#include <linux/syscore_ops.h> +#include <linux/cpufreq.h> +#include <trace/events/sched.h> +#include <clocksource/arm_arch_timer.h> +#include "sched.h" +#include "walt.h" + +#define WINDOW_STATS_RECENT 0 +#define WINDOW_STATS_MAX 1 +#define WINDOW_STATS_MAX_RECENT_AVG 2 +#define WINDOW_STATS_AVG 3 +#define WINDOW_STATS_INVALID_POLICY 4 + +#define EXITING_TASK_MARKER 0xdeaddead + +static __read_mostly unsigned int walt_ravg_hist_size = 5; +static __read_mostly unsigned int walt_window_stats_policy = + WINDOW_STATS_MAX_RECENT_AVG; +static __read_mostly unsigned int walt_account_wait_time = 1; +static __read_mostly unsigned int walt_freq_account_wait_time = 0; +static __read_mostly unsigned int walt_io_is_busy = 0; + +unsigned int sysctl_sched_walt_init_task_load_pct = 15; + +/* 1 -> use PELT based load stats, 0 -> use window-based load stats */ +unsigned int __read_mostly walt_disabled = 0; + +static unsigned int max_possible_efficiency = 1024; +static unsigned int min_possible_efficiency = 1024; + +/* + * Maximum possible frequency across all cpus. Task demand and cpu + * capacity (cpu_power) metrics are scaled in reference to it. + */ +static unsigned int max_possible_freq = 1; + +/* + * Minimum possible max_freq across all cpus. This will be same as + * max_possible_freq on homogeneous systems and could be different from + * max_possible_freq on heterogenous systems. min_max_freq is used to derive + * capacity (cpu_power) of cpus. + */ +static unsigned int min_max_freq = 1; + +static unsigned int max_capacity = 1024; +static unsigned int min_capacity = 1024; +static unsigned int max_load_scale_factor = 1024; +static unsigned int max_possible_capacity = 1024; + +/* Mask of all CPUs that have max_possible_capacity */ +static cpumask_t mpc_mask = CPU_MASK_ALL; + +/* Window size (in ns) */ +__read_mostly unsigned int walt_ravg_window = 20000000; + +/* Min window size (in ns) = 10ms */ +#define MIN_SCHED_RAVG_WINDOW 10000000 + +/* Max window size (in ns) = 1s */ +#define MAX_SCHED_RAVG_WINDOW 1000000000 + +static unsigned int sync_cpu; +static ktime_t ktime_last; +static bool walt_ktime_suspended; + +static unsigned int task_load(struct task_struct *p) +{ + return p->ravg.demand; +} + +void +walt_inc_cumulative_runnable_avg(struct rq *rq, + struct task_struct *p) +{ + rq->cumulative_runnable_avg += p->ravg.demand; +} + +void +walt_dec_cumulative_runnable_avg(struct rq *rq, + struct task_struct *p) +{ + rq->cumulative_runnable_avg -= p->ravg.demand; + BUG_ON((s64)rq->cumulative_runnable_avg < 0); +} + +static void +fixup_cumulative_runnable_avg(struct rq *rq, + struct task_struct *p, s64 task_load_delta) +{ + rq->cumulative_runnable_avg += task_load_delta; + if ((s64)rq->cumulative_runnable_avg < 0) + panic("cra less than zero: tld: %lld, task_load(p) = %u\n", + task_load_delta, task_load(p)); +} + +u64 walt_ktime_clock(void) +{ + if (unlikely(walt_ktime_suspended)) + return ktime_to_ns(ktime_last); + return ktime_get_ns(); +} + +static void walt_resume(void) +{ + walt_ktime_suspended = false; +} + +static int walt_suspend(void) +{ + ktime_last = ktime_get(); + walt_ktime_suspended = true; + return 0; +} + +static struct syscore_ops walt_syscore_ops = { + .resume = walt_resume, + .suspend = walt_suspend +}; + +static int __init walt_init_ops(void) +{ + register_syscore_ops(&walt_syscore_ops); + return 0; +} +late_initcall(walt_init_ops); + +void walt_inc_cfs_cumulative_runnable_avg(struct cfs_rq *cfs_rq, + struct task_struct *p) +{ + cfs_rq->cumulative_runnable_avg += p->ravg.demand; +} + +void walt_dec_cfs_cumulative_runnable_avg(struct cfs_rq *cfs_rq, + struct task_struct *p) +{ + cfs_rq->cumulative_runnable_avg -= p->ravg.demand; +} + +static int exiting_task(struct task_struct *p) +{ + if (p->flags & PF_EXITING) { + if (p->ravg.sum_history[0] != EXITING_TASK_MARKER) { + p->ravg.sum_history[0] = EXITING_TASK_MARKER; + } + return 1; + } + return 0; +} + +static int __init set_walt_ravg_window(char *str) +{ + get_option(&str, &walt_ravg_window); + + walt_disabled = (walt_ravg_window < MIN_SCHED_RAVG_WINDOW || + walt_ravg_window > MAX_SCHED_RAVG_WINDOW); + return 0; +} + +early_param("walt_ravg_window", set_walt_ravg_window); + +static void +update_window_start(struct rq *rq, u64 wallclock) +{ + s64 delta; + int nr_windows; + + delta = wallclock - rq->window_start; + /* If the MPM global timer is cleared, set delta as 0 to avoid kernel BUG happening */ + if (delta < 0) { + if (arch_timer_read_counter() == 0) + delta = 0; + else + BUG_ON(1); + } + + if (delta < walt_ravg_window) + return; + + nr_windows = div64_u64(delta, walt_ravg_window); + rq->window_start += (u64)nr_windows * (u64)walt_ravg_window; +} + +static u64 scale_exec_time(u64 delta, struct rq *rq) +{ + unsigned int cur_freq = rq->cur_freq; + int sf; + + if (unlikely(cur_freq > max_possible_freq)) + cur_freq = rq->max_possible_freq; + + /* round up div64 */ + delta = div64_u64(delta * cur_freq + max_possible_freq - 1, + max_possible_freq); + + sf = DIV_ROUND_UP(rq->efficiency * 1024, max_possible_efficiency); + + delta *= sf; + delta >>= 10; + + return delta; +} + +static int cpu_is_waiting_on_io(struct rq *rq) +{ + if (!walt_io_is_busy) + return 0; + + return atomic_read(&rq->nr_iowait); +} + +void walt_account_irqtime(int cpu, struct task_struct *curr, + u64 delta, u64 wallclock) +{ + struct rq *rq = cpu_rq(cpu); + unsigned long flags, nr_windows; + u64 cur_jiffies_ts; + + raw_spin_lock_irqsave(&rq->lock, flags); + + /* + * cputime (wallclock) uses sched_clock so use the same here for + * consistency. + */ + delta += sched_clock() - wallclock; + cur_jiffies_ts = get_jiffies_64(); + + if (is_idle_task(curr)) + walt_update_task_ravg(curr, rq, IRQ_UPDATE, walt_ktime_clock(), + delta); + + nr_windows = cur_jiffies_ts - rq->irqload_ts; + + if (nr_windows) { + if (nr_windows < 10) { + /* Decay CPU's irqload by 3/4 for each window. */ + rq->avg_irqload *= (3 * nr_windows); + rq->avg_irqload = div64_u64(rq->avg_irqload, + 4 * nr_windows); + } else { + rq->avg_irqload = 0; + } + rq->avg_irqload += rq->cur_irqload; + rq->cur_irqload = 0; + } + + rq->cur_irqload += delta; + rq->irqload_ts = cur_jiffies_ts; + raw_spin_unlock_irqrestore(&rq->lock, flags); +} + + +#define WALT_HIGH_IRQ_TIMEOUT 3 + +u64 walt_irqload(int cpu) { + struct rq *rq = cpu_rq(cpu); + s64 delta; + delta = get_jiffies_64() - rq->irqload_ts; + + /* + * Current context can be preempted by irq and rq->irqload_ts can be + * updated by irq context so that delta can be negative. + * But this is okay and we can safely return as this means there + * was recent irq occurrence. + */ + + if (delta < WALT_HIGH_IRQ_TIMEOUT) + return rq->avg_irqload; + else + return 0; +} + +int walt_cpu_high_irqload(int cpu) { + return walt_irqload(cpu) >= sysctl_sched_walt_cpu_high_irqload; +} + +static int account_busy_for_cpu_time(struct rq *rq, struct task_struct *p, + u64 irqtime, int event) +{ + if (is_idle_task(p)) { + /* TASK_WAKE && TASK_MIGRATE is not possible on idle task! */ + if (event == PICK_NEXT_TASK) + return 0; + + /* PUT_PREV_TASK, TASK_UPDATE && IRQ_UPDATE are left */ + return irqtime || cpu_is_waiting_on_io(rq); + } + + if (event == TASK_WAKE) + return 0; + + if (event == PUT_PREV_TASK || event == IRQ_UPDATE || + event == TASK_UPDATE) + return 1; + + /* Only TASK_MIGRATE && PICK_NEXT_TASK left */ + return walt_freq_account_wait_time; +} + +/* + * Account cpu activity in its busy time counters (rq->curr/prev_runnable_sum) + */ +static void update_cpu_busy_time(struct task_struct *p, struct rq *rq, + int event, u64 wallclock, u64 irqtime) +{ + int new_window, nr_full_windows = 0; + int p_is_curr_task = (p == rq->curr); + u64 mark_start = p->ravg.mark_start; + u64 window_start = rq->window_start; + u32 window_size = walt_ravg_window; + u64 delta; + + new_window = mark_start < window_start; + if (new_window) { + nr_full_windows = div64_u64((window_start - mark_start), + window_size); + if (p->ravg.active_windows < USHRT_MAX) + p->ravg.active_windows++; + } + + /* Handle per-task window rollover. We don't care about the idle + * task or exiting tasks. */ + if (new_window && !is_idle_task(p) && !exiting_task(p)) { + u32 curr_window = 0; + + if (!nr_full_windows) + curr_window = p->ravg.curr_window; + + p->ravg.prev_window = curr_window; + p->ravg.curr_window = 0; + } + + if (!account_busy_for_cpu_time(rq, p, irqtime, event)) { + /* account_busy_for_cpu_time() = 0, so no update to the + * task's current window needs to be made. This could be + * for example + * + * - a wakeup event on a task within the current + * window (!new_window below, no action required), + * - switching to a new task from idle (PICK_NEXT_TASK) + * in a new window where irqtime is 0 and we aren't + * waiting on IO */ + + if (!new_window) + return; + + /* A new window has started. The RQ demand must be rolled + * over if p is the current task. */ + if (p_is_curr_task) { + u64 prev_sum = 0; + + /* p is either idle task or an exiting task */ + if (!nr_full_windows) { + prev_sum = rq->curr_runnable_sum; + } + + rq->prev_runnable_sum = prev_sum; + rq->curr_runnable_sum = 0; + } + + return; + } + + if (!new_window) { + /* account_busy_for_cpu_time() = 1 so busy time needs + * to be accounted to the current window. No rollover + * since we didn't start a new window. An example of this is + * when a task starts execution and then sleeps within the + * same window. */ + + if (!irqtime || !is_idle_task(p) || cpu_is_waiting_on_io(rq)) + delta = wallclock - mark_start; + else + delta = irqtime; + delta = scale_exec_time(delta, rq); + rq->curr_runnable_sum += delta; + if (!is_idle_task(p) && !exiting_task(p)) + p->ravg.curr_window += delta; + + return; + } + + if (!p_is_curr_task) { + /* account_busy_for_cpu_time() = 1 so busy time needs + * to be accounted to the current window. A new window + * has also started, but p is not the current task, so the + * window is not rolled over - just split up and account + * as necessary into curr and prev. The window is only + * rolled over when a new window is processed for the current + * task. + * + * Irqtime can't be accounted by a task that isn't the + * currently running task. */ + + if (!nr_full_windows) { + /* A full window hasn't elapsed, account partial + * contribution to previous completed window. */ + delta = scale_exec_time(window_start - mark_start, rq); + if (!exiting_task(p)) + p->ravg.prev_window += delta; + } else { + /* Since at least one full window has elapsed, + * the contribution to the previous window is the + * full window (window_size). */ + delta = scale_exec_time(window_size, rq); + if (!exiting_task(p)) + p->ravg.prev_window = delta; + } + rq->prev_runnable_sum += delta; + + /* Account piece of busy time in the current window. */ + delta = scale_exec_time(wallclock - window_start, rq); + rq->curr_runnable_sum += delta; + if (!exiting_task(p)) + p->ravg.curr_window = delta; + + return; + } + + if (!irqtime || !is_idle_task(p) || cpu_is_waiting_on_io(rq)) { + /* account_busy_for_cpu_time() = 1 so busy time needs + * to be accounted to the current window. A new window + * has started and p is the current task so rollover is + * needed. If any of these three above conditions are true + * then this busy time can't be accounted as irqtime. + * + * Busy time for the idle task or exiting tasks need not + * be accounted. + * + * An example of this would be a task that starts execution + * and then sleeps once a new window has begun. */ + + if (!nr_full_windows) { + /* A full window hasn't elapsed, account partial + * contribution to previous completed window. */ + delta = scale_exec_time(window_start - mark_start, rq); + if (!is_idle_task(p) && !exiting_task(p)) + p->ravg.prev_window += delta; + + delta += rq->curr_runnable_sum; + } else { + /* Since at least one full window has elapsed, + * the contribution to the previous window is the + * full window (window_size). */ + delta = scale_exec_time(window_size, rq); + if (!is_idle_task(p) && !exiting_task(p)) + p->ravg.prev_window = delta; + + } + /* + * Rollover for normal runnable sum is done here by overwriting + * the values in prev_runnable_sum and curr_runnable_sum. + * Rollover for new task runnable sum has completed by previous + * if-else statement. + */ + rq->prev_runnable_sum = delta; + + /* Account piece of busy time in the current window. */ + delta = scale_exec_time(wallclock - window_start, rq); + rq->curr_runnable_sum = delta; + if (!is_idle_task(p) && !exiting_task(p)) + p->ravg.curr_window = delta; + + return; + } + + if (irqtime) { + /* account_busy_for_cpu_time() = 1 so busy time needs + * to be accounted to the current window. A new window + * has started and p is the current task so rollover is + * needed. The current task must be the idle task because + * irqtime is not accounted for any other task. + * + * Irqtime will be accounted each time we process IRQ activity + * after a period of idleness, so we know the IRQ busy time + * started at wallclock - irqtime. */ + + BUG_ON(!is_idle_task(p)); + mark_start = wallclock - irqtime; + + /* Roll window over. If IRQ busy time was just in the current + * window then that is all that need be accounted. */ + rq->prev_runnable_sum = rq->curr_runnable_sum; + if (mark_start > window_start) { + rq->curr_runnable_sum = scale_exec_time(irqtime, rq); + return; + } + + /* The IRQ busy time spanned multiple windows. Process the + * busy time preceding the current window start first. */ + delta = window_start - mark_start; + if (delta > window_size) + delta = window_size; + delta = scale_exec_time(delta, rq); + rq->prev_runnable_sum += delta; + + /* Process the remaining IRQ busy time in the current window. */ + delta = wallclock - window_start; + rq->curr_runnable_sum = scale_exec_time(delta, rq); + + return; + } + + BUG(); +} + +static int account_busy_for_task_demand(struct task_struct *p, int event) +{ + /* No need to bother updating task demand for exiting tasks + * or the idle task. */ + if (exiting_task(p) || is_idle_task(p)) + return 0; + + /* When a task is waking up it is completing a segment of non-busy + * time. Likewise, if wait time is not treated as busy time, then + * when a task begins to run or is migrated, it is not running and + * is completing a segment of non-busy time. */ + if (event == TASK_WAKE || (!walt_account_wait_time && + (event == PICK_NEXT_TASK || event == TASK_MIGRATE))) + return 0; + + return 1; +} + +/* + * Called when new window is starting for a task, to record cpu usage over + * recently concluded window(s). Normally 'samples' should be 1. It can be > 1 + * when, say, a real-time task runs without preemption for several windows at a + * stretch. + */ +static void update_history(struct rq *rq, struct task_struct *p, + u32 runtime, int samples, int event) +{ + u32 *hist = &p->ravg.sum_history[0]; + int ridx, widx; + u32 max = 0, avg, demand; + u64 sum = 0; + + /* Ignore windows where task had no activity */ + if (!runtime || is_idle_task(p) || exiting_task(p) || !samples) + goto done; + + /* Push new 'runtime' value onto stack */ + widx = walt_ravg_hist_size - 1; + ridx = widx - samples; + for (; ridx >= 0; --widx, --ridx) { + hist[widx] = hist[ridx]; + sum += hist[widx]; + if (hist[widx] > max) + max = hist[widx]; + } + + for (widx = 0; widx < samples && widx < walt_ravg_hist_size; widx++) { + hist[widx] = runtime; + sum += hist[widx]; + if (hist[widx] > max) + max = hist[widx]; + } + + p->ravg.sum = 0; + + if (walt_window_stats_policy == WINDOW_STATS_RECENT) { + demand = runtime; + } else if (walt_window_stats_policy == WINDOW_STATS_MAX) { + demand = max; + } else { + avg = div64_u64(sum, walt_ravg_hist_size); + if (walt_window_stats_policy == WINDOW_STATS_AVG) + demand = avg; + else + demand = max(avg, runtime); + } + + /* + * A throttled deadline sched class task gets dequeued without + * changing p->on_rq. Since the dequeue decrements hmp stats + * avoid decrementing it here again. + */ + if (task_on_rq_queued(p) && (!task_has_dl_policy(p) || + !p->dl.dl_throttled)) + fixup_cumulative_runnable_avg(rq, p, demand); + + p->ravg.demand = demand; + +done: + trace_walt_update_history(rq, p, runtime, samples, event); + return; +} + +static void add_to_task_demand(struct rq *rq, struct task_struct *p, + u64 delta) +{ + delta = scale_exec_time(delta, rq); + p->ravg.sum += delta; + if (unlikely(p->ravg.sum > walt_ravg_window)) + p->ravg.sum = walt_ravg_window; +} + +/* + * Account cpu demand of task and/or update task's cpu demand history + * + * ms = p->ravg.mark_start; + * wc = wallclock + * ws = rq->window_start + * + * Three possibilities: + * + * a) Task event is contained within one window. + * window_start < mark_start < wallclock + * + * ws ms wc + * | | | + * V V V + * |---------------| + * + * In this case, p->ravg.sum is updated *iff* event is appropriate + * (ex: event == PUT_PREV_TASK) + * + * b) Task event spans two windows. + * mark_start < window_start < wallclock + * + * ms ws wc + * | | | + * V V V + * -----|------------------- + * + * In this case, p->ravg.sum is updated with (ws - ms) *iff* event + * is appropriate, then a new window sample is recorded followed + * by p->ravg.sum being set to (wc - ws) *iff* event is appropriate. + * + * c) Task event spans more than two windows. + * + * ms ws_tmp ws wc + * | | | | + * V V V V + * ---|-------|-------|-------|-------|------ + * | | + * |<------ nr_full_windows ------>| + * + * In this case, p->ravg.sum is updated with (ws_tmp - ms) first *iff* + * event is appropriate, window sample of p->ravg.sum is recorded, + * 'nr_full_window' samples of window_size is also recorded *iff* + * event is appropriate and finally p->ravg.sum is set to (wc - ws) + * *iff* event is appropriate. + * + * IMPORTANT : Leave p->ravg.mark_start unchanged, as update_cpu_busy_time() + * depends on it! + */ +static void update_task_demand(struct task_struct *p, struct rq *rq, + int event, u64 wallclock) +{ + u64 mark_start = p->ravg.mark_start; + u64 delta, window_start = rq->window_start; + int new_window, nr_full_windows; + u32 window_size = walt_ravg_window; + + new_window = mark_start < window_start; + if (!account_busy_for_task_demand(p, event)) { + if (new_window) + /* If the time accounted isn't being accounted as + * busy time, and a new window started, only the + * previous window need be closed out with the + * pre-existing demand. Multiple windows may have + * elapsed, but since empty windows are dropped, + * it is not necessary to account those. */ + update_history(rq, p, p->ravg.sum, 1, event); + return; + } + + if (!new_window) { + /* The simple case - busy time contained within the existing + * window. */ + add_to_task_demand(rq, p, wallclock - mark_start); + return; + } + + /* Busy time spans at least two windows. Temporarily rewind + * window_start to first window boundary after mark_start. */ + delta = window_start - mark_start; + nr_full_windows = div64_u64(delta, window_size); + window_start -= (u64)nr_full_windows * (u64)window_size; + + /* Process (window_start - mark_start) first */ + add_to_task_demand(rq, p, window_start - mark_start); + + /* Push new sample(s) into task's demand history */ + update_history(rq, p, p->ravg.sum, 1, event); + if (nr_full_windows) + update_history(rq, p, scale_exec_time(window_size, rq), + nr_full_windows, event); + + /* Roll window_start back to current to process any remainder + * in current window. */ + window_start += (u64)nr_full_windows * (u64)window_size; + + /* Process (wallclock - window_start) next */ + mark_start = window_start; + add_to_task_demand(rq, p, wallclock - mark_start); +} + +/* Reflect task activity on its demand and cpu's busy time statistics */ +void walt_update_task_ravg(struct task_struct *p, struct rq *rq, + int event, u64 wallclock, u64 irqtime) +{ + if (walt_disabled || !rq->window_start) + return; + + lockdep_assert_held(&rq->lock); + + update_window_start(rq, wallclock); + + if (!p->ravg.mark_start) + goto done; + + update_task_demand(p, rq, event, wallclock); + update_cpu_busy_time(p, rq, event, wallclock, irqtime); + +done: + trace_walt_update_task_ravg(p, rq, event, wallclock, irqtime); + + p->ravg.mark_start = wallclock; +} + +unsigned long __weak arch_get_cpu_efficiency(int cpu) +{ + return SCHED_LOAD_SCALE; +} + +void walt_init_cpu_efficiency(void) +{ + int i, efficiency; + unsigned int max = 0, min = UINT_MAX; + + for_each_possible_cpu(i) { + efficiency = arch_get_cpu_efficiency(i); + cpu_rq(i)->efficiency = efficiency; + + if (efficiency > max) + max = efficiency; + if (efficiency < min) + min = efficiency; + } + + if (max) + max_possible_efficiency = max; + + if (min) + min_possible_efficiency = min; +} + +static void reset_task_stats(struct task_struct *p) +{ + u32 sum = 0; + + if (exiting_task(p)) + sum = EXITING_TASK_MARKER; + + memset(&p->ravg, 0, sizeof(struct ravg)); + /* Retain EXITING_TASK marker */ + p->ravg.sum_history[0] = sum; +} + +void walt_mark_task_starting(struct task_struct *p) +{ + u64 wallclock; + struct rq *rq = task_rq(p); + + if (!rq->window_start) { + reset_task_stats(p); + return; + } + + wallclock = walt_ktime_clock(); + p->ravg.mark_start = wallclock; +} + +void walt_set_window_start(struct rq *rq) +{ + int cpu = cpu_of(rq); + struct rq *sync_rq = cpu_rq(sync_cpu); + + if (rq->window_start) + return; + + if (cpu == sync_cpu) { + rq->window_start = walt_ktime_clock(); + } else { + raw_spin_unlock(&rq->lock); + double_rq_lock(rq, sync_rq); + rq->window_start = cpu_rq(sync_cpu)->window_start; + rq->curr_runnable_sum = rq->prev_runnable_sum = 0; + raw_spin_unlock(&sync_rq->lock); + } + + rq->curr->ravg.mark_start = rq->window_start; +} + +void walt_migrate_sync_cpu(int cpu) +{ + if (cpu == sync_cpu) + sync_cpu = smp_processor_id(); +} + +void walt_fixup_busy_time(struct task_struct *p, int new_cpu) +{ + struct rq *src_rq = task_rq(p); + struct rq *dest_rq = cpu_rq(new_cpu); + u64 wallclock; + + if (!p->on_rq && p->state != TASK_WAKING) + return; + + if (exiting_task(p)) { + return; + } + + if (p->state == TASK_WAKING) + double_rq_lock(src_rq, dest_rq); + + wallclock = walt_ktime_clock(); + + walt_update_task_ravg(task_rq(p)->curr, task_rq(p), + TASK_UPDATE, wallclock, 0); + walt_update_task_ravg(dest_rq->curr, dest_rq, + TASK_UPDATE, wallclock, 0); + + walt_update_task_ravg(p, task_rq(p), TASK_MIGRATE, wallclock, 0); + + if (p->ravg.curr_window) { + src_rq->curr_runnable_sum -= p->ravg.curr_window; + dest_rq->curr_runnable_sum += p->ravg.curr_window; + } + + if (p->ravg.prev_window) { + src_rq->prev_runnable_sum -= p->ravg.prev_window; + dest_rq->prev_runnable_sum += p->ravg.prev_window; + } + + if ((s64)src_rq->prev_runnable_sum < 0) { + src_rq->prev_runnable_sum = 0; + WARN_ON(1); + } + if ((s64)src_rq->curr_runnable_sum < 0) { + src_rq->curr_runnable_sum = 0; + WARN_ON(1); + } + + trace_walt_migration_update_sum(src_rq, p); + trace_walt_migration_update_sum(dest_rq, p); + + if (p->state == TASK_WAKING) + double_rq_unlock(src_rq, dest_rq); +} + +/* Keep track of max/min capacity possible across CPUs "currently" */ +static void __update_min_max_capacity(void) +{ + int i; + int max = 0, min = INT_MAX; + + for_each_online_cpu(i) { + if (cpu_rq(i)->capacity > max) + max = cpu_rq(i)->capacity; + if (cpu_rq(i)->capacity < min) + min = cpu_rq(i)->capacity; + } + + max_capacity = max; + min_capacity = min; +} + +static void update_min_max_capacity(void) +{ + unsigned long flags; + int i; + + local_irq_save(flags); + for_each_possible_cpu(i) + raw_spin_lock(&cpu_rq(i)->lock); + + __update_min_max_capacity(); + + for_each_possible_cpu(i) + raw_spin_unlock(&cpu_rq(i)->lock); + local_irq_restore(flags); +} + +/* + * Return 'capacity' of a cpu in reference to "least" efficient cpu, such that + * least efficient cpu gets capacity of 1024 + */ +static unsigned long capacity_scale_cpu_efficiency(int cpu) +{ + return (1024 * cpu_rq(cpu)->efficiency) / min_possible_efficiency; +} + +/* + * Return 'capacity' of a cpu in reference to cpu with lowest max_freq + * (min_max_freq), such that one with lowest max_freq gets capacity of 1024. + */ +static unsigned long capacity_scale_cpu_freq(int cpu) +{ + return (1024 * cpu_rq(cpu)->max_freq) / min_max_freq; +} + +/* + * Return load_scale_factor of a cpu in reference to "most" efficient cpu, so + * that "most" efficient cpu gets a load_scale_factor of 1 + */ +static unsigned long load_scale_cpu_efficiency(int cpu) +{ + return DIV_ROUND_UP(1024 * max_possible_efficiency, + cpu_rq(cpu)->efficiency); +} + +/* + * Return load_scale_factor of a cpu in reference to cpu with best max_freq + * (max_possible_freq), so that one with best max_freq gets a load_scale_factor + * of 1. + */ +static unsigned long load_scale_cpu_freq(int cpu) +{ + return DIV_ROUND_UP(1024 * max_possible_freq, cpu_rq(cpu)->max_freq); +} + +static int compute_capacity(int cpu) +{ + int capacity = 1024; + + capacity *= capacity_scale_cpu_efficiency(cpu); + capacity >>= 10; + + capacity *= capacity_scale_cpu_freq(cpu); + capacity >>= 10; + + return capacity; +} + +static int compute_load_scale_factor(int cpu) +{ + int load_scale = 1024; + + /* + * load_scale_factor accounts for the fact that task load + * is in reference to "best" performing cpu. Task's load will need to be + * scaled (up) by a factor to determine suitability to be placed on a + * (little) cpu. + */ + load_scale *= load_scale_cpu_efficiency(cpu); + load_scale >>= 10; + + load_scale *= load_scale_cpu_freq(cpu); + load_scale >>= 10; + + return load_scale; +} + +static int cpufreq_notifier_policy(struct notifier_block *nb, + unsigned long val, void *data) +{ + struct cpufreq_policy *policy = (struct cpufreq_policy *)data; + int i, update_max = 0; + u64 highest_mpc = 0, highest_mplsf = 0; + const struct cpumask *cpus = policy->related_cpus; + unsigned int orig_min_max_freq = min_max_freq; + unsigned int orig_max_possible_freq = max_possible_freq; + /* Initialized to policy->max in case policy->related_cpus is empty! */ + unsigned int orig_max_freq = policy->max; + + if (val != CPUFREQ_NOTIFY && val != CPUFREQ_REMOVE_POLICY && + val != CPUFREQ_CREATE_POLICY) + return 0; + + if (val == CPUFREQ_REMOVE_POLICY || val == CPUFREQ_CREATE_POLICY) { + update_min_max_capacity(); + return 0; + } + + for_each_cpu(i, policy->related_cpus) { + cpumask_copy(&cpu_rq(i)->freq_domain_cpumask, + policy->related_cpus); + orig_max_freq = cpu_rq(i)->max_freq; + cpu_rq(i)->min_freq = policy->min; + cpu_rq(i)->max_freq = policy->max; + cpu_rq(i)->cur_freq = policy->cur; + cpu_rq(i)->max_possible_freq = policy->cpuinfo.max_freq; + } + + max_possible_freq = max(max_possible_freq, policy->cpuinfo.max_freq); + if (min_max_freq == 1) + min_max_freq = UINT_MAX; + min_max_freq = min(min_max_freq, policy->cpuinfo.max_freq); + BUG_ON(!min_max_freq); + BUG_ON(!policy->max); + + /* Changes to policy other than max_freq don't require any updates */ + if (orig_max_freq == policy->max) + return 0; + + /* + * A changed min_max_freq or max_possible_freq (possible during bootup) + * needs to trigger re-computation of load_scale_factor and capacity for + * all possible cpus (even those offline). It also needs to trigger + * re-computation of nr_big_task count on all online cpus. + * + * A changed rq->max_freq otoh needs to trigger re-computation of + * load_scale_factor and capacity for just the cluster of cpus involved. + * Since small task definition depends on max_load_scale_factor, a + * changed load_scale_factor of one cluster could influence + * classification of tasks in another cluster. Hence a changed + * rq->max_freq will need to trigger re-computation of nr_big_task + * count on all online cpus. + * + * While it should be sufficient for nr_big_tasks to be + * re-computed for only online cpus, we have inadequate context + * information here (in policy notifier) with regard to hotplug-safety + * context in which notification is issued. As a result, we can't use + * get_online_cpus() here, as it can lead to deadlock. Until cpufreq is + * fixed up to issue notification always in hotplug-safe context, + * re-compute nr_big_task for all possible cpus. + */ + + if (orig_min_max_freq != min_max_freq || + orig_max_possible_freq != max_possible_freq) { + cpus = cpu_possible_mask; + update_max = 1; + } + + /* + * Changed load_scale_factor can trigger reclassification of tasks as + * big or small. Make this change "atomic" so that tasks are accounted + * properly due to changed load_scale_factor + */ + for_each_cpu(i, cpus) { + struct rq *rq = cpu_rq(i); + + rq->capacity = compute_capacity(i); + rq->load_scale_factor = compute_load_scale_factor(i); + + if (update_max) { + u64 mpc, mplsf; + + mpc = div_u64(((u64) rq->capacity) * + rq->max_possible_freq, rq->max_freq); + rq->max_possible_capacity = (int) mpc; + + mplsf = div_u64(((u64) rq->load_scale_factor) * + rq->max_possible_freq, rq->max_freq); + + if (mpc > highest_mpc) { + highest_mpc = mpc; + cpumask_clear(&mpc_mask); + cpumask_set_cpu(i, &mpc_mask); + } else if (mpc == highest_mpc) { + cpumask_set_cpu(i, &mpc_mask); + } + + if (mplsf > highest_mplsf) + highest_mplsf = mplsf; + } + } + + if (update_max) { + max_possible_capacity = highest_mpc; + max_load_scale_factor = highest_mplsf; + } + + __update_min_max_capacity(); + + return 0; +} + +static int cpufreq_notifier_trans(struct notifier_block *nb, + unsigned long val, void *data) +{ + struct cpufreq_freqs *freq = (struct cpufreq_freqs *)data; + unsigned int cpu = freq->cpu, new_freq = freq->new; + unsigned long flags; + int i; + + if (val != CPUFREQ_POSTCHANGE) + return 0; + + BUG_ON(!new_freq); + + if (cpu_rq(cpu)->cur_freq == new_freq) + return 0; + + for_each_cpu(i, &cpu_rq(cpu)->freq_domain_cpumask) { + struct rq *rq = cpu_rq(i); + + raw_spin_lock_irqsave(&rq->lock, flags); + walt_update_task_ravg(rq->curr, rq, TASK_UPDATE, + walt_ktime_clock(), 0); + rq->cur_freq = new_freq; + raw_spin_unlock_irqrestore(&rq->lock, flags); + } + + return 0; +} + +static struct notifier_block notifier_policy_block = { + .notifier_call = cpufreq_notifier_policy +}; + +static struct notifier_block notifier_trans_block = { + .notifier_call = cpufreq_notifier_trans +}; + +static int register_sched_callback(void) +{ + int ret; + + ret = cpufreq_register_notifier(¬ifier_policy_block, + CPUFREQ_POLICY_NOTIFIER); + + if (!ret) + ret = cpufreq_register_notifier(¬ifier_trans_block, + CPUFREQ_TRANSITION_NOTIFIER); + + return 0; +} + +/* + * cpufreq callbacks can be registered at core_initcall or later time. + * Any registration done prior to that is "forgotten" by cpufreq. See + * initialization of variable init_cpufreq_transition_notifier_list_called + * for further information. + */ +core_initcall(register_sched_callback); + +void walt_init_new_task_load(struct task_struct *p) +{ + int i; + u32 init_load_windows = + div64_u64((u64)sysctl_sched_walt_init_task_load_pct * + (u64)walt_ravg_window, 100); + u32 init_load_pct = current->init_load_pct; + + p->init_load_pct = 0; + memset(&p->ravg, 0, sizeof(struct ravg)); + + if (init_load_pct) { + init_load_windows = div64_u64((u64)init_load_pct * + (u64)walt_ravg_window, 100); + } + + p->ravg.demand = init_load_windows; + for (i = 0; i < RAVG_HIST_SIZE_MAX; ++i) + p->ravg.sum_history[i] = init_load_windows; +} |