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scx_lavd: improve the equation for calculating ineligibility duration
This commit include a few changes: - treat a new forked task more conservatively - defer the execution of more tasks for longer time using ineligibility duration - consider if a task is waken up in calculating ineligibility duration
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Changwoo Min
parent
5e194330f0
commit
c38e749c36
@ -69,9 +69,10 @@ enum consts {
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LAVD_SLICE_BOOST_MAX_FT = 3, /* maximum additional 3x of slice */
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LAVD_SLICE_BOOST_MAX_STEP = 6, /* 6 slice exhausitions in a row */
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LAVD_GREEDY_RATIO_NEW = 2000,
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LAVD_NEW_PROC_PENALITY = 5,
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LAVD_GREEDY_RATIO_NEW = (1000 * LAVD_NEW_PROC_PENALITY),
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LAVD_ELIGIBLE_TIME_MAX = (1ULL * LAVD_TIME_ONE_SEC),
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LAVD_ELIGIBLE_TIME_MAX = (9999ULL * LAVD_TIME_ONE_SEC),
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LAVD_CPU_UTIL_MAX = 1000, /* 100.0% */
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LAVD_CPU_UTIL_MAX_FOR_CPUPERF = 850, /* 85.0% */
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@ -213,7 +214,6 @@ struct task_ctx {
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u64 slice_ns; /* time slice */
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u32 greedy_ratio; /* task's overscheduling ratio compared to its nice priority */
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u32 lat_cri; /* calculated latency criticality */
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u32 starv_cri; /* calculated starvation criticality */
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volatile s32 victim_cpu;
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u16 slice_boost_prio; /* how many times a task fully consumed the slice */
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@ -231,7 +231,7 @@ struct task_ctx_x {
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u32 cpu_id; /* where a task ran */
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u64 cpu_util; /* cpu utilization in [0..100] */
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u32 avg_perf_cri; /* average performance criticality */
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u32 avg_lat_cri; /* average latency criticality */
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u32 thr_lat_cri; /* threshold for latency criticality */
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u32 nr_active; /* number of active cores */
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u32 cpuperf_cur; /* CPU's current performance target */
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};
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@ -434,7 +434,7 @@ int submit_task_ctx(struct task_struct *p, struct task_ctx *taskc, u32 cpu_id)
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m->taskc_x.static_prio = get_nice_prio(p);
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m->taskc_x.cpu_util = cpuc->util / 10;
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m->taskc_x.cpu_id = cpu_id;
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m->taskc_x.avg_lat_cri = stat_cur->avg_lat_cri;
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m->taskc_x.thr_lat_cri = stat_cur->thr_lat_cri;
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m->taskc_x.avg_perf_cri = stat_cur->avg_perf_cri;
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m->taskc_x.nr_active = stat_cur->nr_active;
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m->taskc_x.cpuperf_cur = cpuc->cpuperf_cur;
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@ -939,7 +939,7 @@ static bool is_wakeup_ef(u64 enq_flags)
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return !!(enq_flags & SCX_ENQ_WAKEUP);
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}
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static u64 calc_eligible_delta(struct task_ctx *taskc)
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static u64 calc_eligible_delta(struct task_ctx *taskc, u64 enq_flags)
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{
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/*
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* We calculate how long a task should be ineligible for execution. To
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@ -961,6 +961,7 @@ static u64 calc_eligible_delta(struct task_ctx *taskc)
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*/
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struct sys_stat *stat_cur = get_sys_stat_cur();
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u64 delta_ns, lat_cri_ft;
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bool is_wakeup;
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/*
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* Get how greedy this task has been to enforce fairness if necessary.
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@ -977,26 +978,28 @@ static u64 calc_eligible_delta(struct task_ctx *taskc)
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goto out;
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}
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is_wakeup = is_wakeup_ef(enq_flags);
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/*
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* Calculate ineligible duration based on greedy ratio, run_freq, and
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* lat_cri.
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* lat_cri. Prioritize wake-up tasks.
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*/
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delta_ns = (LAVD_TIME_ONE_SEC / (1000 * (taskc->run_freq + 1))) *
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taskc->greedy_ratio;
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lat_cri_ft = taskc->lat_cri + (is_wakeup * (LAVD_LC_WAKEUP_FT >> 1));
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if (stat_cur->avg_lat_cri < taskc->lat_cri) {
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if (have_scheduled(taskc) && stat_cur->thr_lat_cri < lat_cri_ft) {
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/*
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* Prioritize above-average latency-critical tasks.
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* Prioritize far above-average latency-critical tasks.
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*/
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lat_cri_ft = taskc->lat_cri - stat_cur->avg_lat_cri + 1;
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lat_cri_ft = lat_cri_ft - stat_cur->thr_lat_cri + 1;
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delta_ns /= lat_cri_ft;
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}
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else {
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/*
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* Deprioritize below-average latency-critical tasks.
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*/
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lat_cri_ft = stat_cur->avg_lat_cri - taskc->lat_cri + 1;
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lat_cri_ft = stat_cur->thr_lat_cri - lat_cri_ft + 1;
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delta_ns *= lat_cri_ft;
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}
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@ -1074,22 +1077,21 @@ static void calc_lat_cri(struct task_struct *p, struct task_ctx *taskc)
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taskc->lat_cri = lat_cri;
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}
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static void calc_starv_cri(struct task_ctx *taskc, bool is_wakeup)
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static u64 calc_starv_cri(struct task_ctx *taskc, bool is_wakeup)
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{
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taskc->starv_cri = calc_starvation_factor(taskc) +
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(is_wakeup * LAVD_LC_WAKEUP_FT);
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return calc_starvation_factor(taskc) + (is_wakeup * LAVD_LC_WAKEUP_FT);
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}
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static void calc_virtual_deadline_delta(struct task_struct *p,
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struct task_ctx *taskc, u64 enq_flags)
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{
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bool is_wakeup;
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u64 sc;
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is_wakeup = is_wakeup_ef(enq_flags);
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calc_lat_cri(p, taskc);
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calc_starv_cri(taskc, is_wakeup);
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taskc->vdeadline_delta_ns = taskc->run_time_ns / (taskc->lat_cri +
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taskc->starv_cri);
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sc = calc_starv_cri(taskc, is_wakeup);
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taskc->vdeadline_delta_ns = taskc->run_time_ns / (taskc->lat_cri + sc);
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}
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static u64 calc_task_load_actual(struct task_ctx *taskc)
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@ -1377,7 +1379,7 @@ static void calc_when_to_run(struct task_struct *p, struct task_ctx *taskc,
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* overscheduled - eligible_time_ns.
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*/
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calc_virtual_deadline_delta(p, taskc, enq_flags);
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calc_eligible_delta(taskc);
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calc_eligible_delta(taskc, enq_flags);
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/*
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* Update the logical clock of the virtual deadline including
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@ -1699,7 +1701,7 @@ static bool is_lat_cri_task(struct task_ctx *taskc)
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{
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struct sys_stat *stat_cur = get_sys_stat_cur();
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return taskc->lat_cri > stat_cur->avg_lat_cri;
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return taskc->lat_cri > stat_cur->thr_lat_cri;
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}
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static void put_global_rq(struct task_struct *p, struct task_ctx *taskc,
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@ -2531,6 +2533,7 @@ void BPF_STRUCT_OPS(lavd_update_idle, s32 cpu, bool idle)
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static void init_task_ctx(struct task_struct *p, struct task_ctx *taskc)
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{
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struct sys_stat *stat_cur = get_sys_stat_cur();
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u64 now = bpf_ktime_get_ns();
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memset(taskc, 0, sizeof(*taskc));
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@ -2538,6 +2541,7 @@ static void init_task_ctx(struct task_struct *p, struct task_ctx *taskc)
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taskc->last_stopping_clk = now; /* for run_time_ns */
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taskc->run_time_ns = LAVD_SLICE_MAX_NS;
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taskc->victim_cpu = (s32)LAVD_CPU_ID_NONE;
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taskc->svc_time = stat_cur->avg_svc_time * LAVD_NEW_PROC_PENALITY;
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}
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void BPF_STRUCT_OPS(lavd_enable, struct task_struct *p)
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@ -344,7 +344,7 @@ impl<'a> Scheduler<'a> {
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"slc_ns",
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"grdy_rt",
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"lat_cri",
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"avg_lc",
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"thr_lc",
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"st_prio",
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"slc_bst",
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"run_freq",
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@ -387,7 +387,7 @@ impl<'a> Scheduler<'a> {
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tc.slice_ns,
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tc.greedy_ratio,
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tc.lat_cri,
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tx.avg_lat_cri,
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tx.thr_lat_cri,
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tx.static_prio,
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tc.slice_boost_prio,
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tc.run_freq,
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