include/linux/psi_types.h

   1 #ifndef _LINUX_PSI_TYPES_H
   2 #define _LINUX_PSI_TYPES_H
   3
   4 #include <linux/kthread.h>
   5 #include <linux/seqlock.h>
   6 #include <linux/types.h>
   7 #include <linux/kref.h>
   8 #include <linux/wait.h>
   9
  10 #ifdef CONFIG_PSI
  11
  12 /* Tracked task states */
  13 enum psi_task_count {
  14         NR_IOWAIT,
  15         NR_MEMSTALL,
  16         NR_RUNNING,
  17         /*
  18          * This can't have values other than 0 or 1 and could be
  19          * implemented as a bit flag. But for now we still have room
  20          * in the first cacheline of psi_group_cpu, and this way we
  21          * don't have to special case any state tracking for it.
  22          */
  23         NR_ONCPU,
  24         NR_PSI_TASK_COUNTS = 4,
  25 };
  26
  27 /* Task state bitmasks */
  28 #define TSK_IOWAIT      (1 << NR_IOWAIT)
  29 #define TSK_MEMSTALL    (1 << NR_MEMSTALL)
  30 #define TSK_RUNNING     (1 << NR_RUNNING)
  31 #define TSK_ONCPU       (1 << NR_ONCPU)
  32
  33 /* Resources that workloads could be stalled on */
  34 enum psi_res {
  35         PSI_IO,
  36         PSI_MEM,
  37         PSI_CPU,
  38         NR_PSI_RESOURCES = 3,
  39 };
  40
  41 /*
  42  * Pressure states for each resource:
  43  *
  44  * SOME: Stalled tasks & working tasks
  45  * FULL: Stalled tasks & no working tasks
  46  */
  47 enum psi_states {
  48         PSI_IO_SOME,
  49         PSI_IO_FULL,
  50         PSI_MEM_SOME,
  51         PSI_MEM_FULL,
  52         PSI_CPU_SOME,
  53         /* Only per-CPU, to weigh the CPU in the global average: */
  54         PSI_NONIDLE,
  55         NR_PSI_STATES = 6,
  56 };
  57
  58 enum psi_aggregators {
  59         PSI_AVGS = 0,
  60         PSI_POLL,
  61         NR_PSI_AGGREGATORS,
  62 };
  63
  64 struct psi_group_cpu {
  65         /* 1st cacheline updated by the scheduler */
  66
  67         /* Aggregator needs to know of concurrent changes */
  68         seqcount_t seq ____cacheline_aligned_in_smp;
  69
  70         /* States of the tasks belonging to this group */
  71         unsigned int tasks[NR_PSI_TASK_COUNTS];
  72
  73         /* Aggregate pressure state derived from the tasks */
  74         u32 state_mask;
  75
  76         /* Period time sampling buckets for each state of interest (ns) */
  77         u32 times[NR_PSI_STATES];
  78
  79         /* Time of last task change in this group (rq_clock) */
  80         u64 state_start;
  81
  82         /* 2nd cacheline updated by the aggregator */
  83
  84         /* Delta detection against the sampling buckets */
  85         u32 times_prev[NR_PSI_AGGREGATORS][NR_PSI_STATES]
  86                         ____cacheline_aligned_in_smp;
  87 };
  88
  89 /* PSI growth tracking window */
  90 struct psi_window {
  91         /* Window size in ns */
  92         u64 size;
  93
  94         /* Start time of the current window in ns */
  95         u64 start_time;
  96
  97         /* Value at the start of the window */
  98         u64 start_value;
  99
 100         /* Value growth in the previous window */
 101         u64 prev_growth;
 102 };
 103
 104 struct psi_trigger {
 105         /* PSI state being monitored by the trigger */
 106         enum psi_states state;
 107
 108         /* User-spacified threshold in ns */
 109         u64 threshold;
 110
 111         /* List node inside triggers list */
 112         struct list_head node;
 113
 114         /* Backpointer needed during trigger destruction */
 115         struct psi_group *group;
 116
 117         /* Wait queue for polling */
 118         wait_queue_head_t event_wait;
 119
 120         /* Pending event flag */
 121         int event;
 122
 123         /* Tracking window */
 124         struct psi_window win;
 125
 126         /*
 127          * Time last event was generated. Used for rate-limiting
 128          * events to one per window
 129          */
 130         u64 last_event_time;
 131
 132         /* Refcounting to prevent premature destruction */
 133         struct kref refcount;
 134 };
 135
 136 struct psi_group {
 137         /* Protects data used by the aggregator */
 138         struct mutex avgs_lock;
 139
 140         /* Per-cpu task state & time tracking */
 141         struct psi_group_cpu __percpu *pcpu;
 142
 143         /* Running pressure averages */
 144         u64 avg_total[NR_PSI_STATES - 1];
 145         u64 avg_last_update;
 146         u64 avg_next_update;
 147
 148         /* Aggregator work control */
 149         struct delayed_work avgs_work;
 150
 151         /* Total stall times and sampled pressure averages */
 152         u64 total[NR_PSI_AGGREGATORS][NR_PSI_STATES - 1];
 153         unsigned long avg[NR_PSI_STATES - 1][3];
 154
 155         /* Monitor work control */
 156         atomic_t poll_scheduled;
 157         struct kthread_worker __rcu *poll_kworker;
 158         struct kthread_delayed_work poll_work;
 159
 160         /* Protects data used by the monitor */
 161         struct mutex trigger_lock;
 162
 163         /* Configured polling triggers */
 164         struct list_head triggers;
 165         u32 nr_triggers[NR_PSI_STATES - 1];
 166         u32 poll_states;
 167         u64 poll_min_period;
 168
 169         /* Total stall times at the start of monitor activation */
 170         u64 polling_total[NR_PSI_STATES - 1];
 171         u64 polling_next_update;
 172         u64 polling_until;
 173 };
 174
 175 #else /* CONFIG_PSI */
 176
 177 struct psi_group { };
 178
 179 #endif /* CONFIG_PSI */
 180
 181 #endif /* _LINUX_PSI_TYPES_H */