flow.c

   1 #include "fio.h"
   2 #include "fio_sem.h"
   3 #include "smalloc.h"
   4 #include "flist.h"
   5
   6 struct fio_flow {
   7         unsigned int refs;
   8         struct flist_head list;
   9         unsigned int id;
  10         unsigned long long flow_counter;
  11         unsigned int total_weight;
  12 };
  13
  14 static struct flist_head *flow_list;
  15 static struct fio_sem *flow_lock;
  16
  17 int flow_threshold_exceeded(struct thread_data *td)
  18 {
  19         struct fio_flow *flow = td->flow;
  20         double flow_counter_ratio, flow_weight_ratio;
  21
  22         if (!flow)
  23                 return 0;
  24
  25         flow_counter_ratio = (double)td->flow_counter /
  26                 atomic_load_relaxed(&flow->flow_counter);
  27         flow_weight_ratio = (double)td->o.flow /
  28                 atomic_load_relaxed(&flow->total_weight);
  29
  30         /*
  31          * each thread/process executing a fio job will stall based on the
  32          * expected  user ratio for a given flow_id group. the idea is to keep
  33          * 2 counters, flow and job-specific counter to test if the
  34          * ratio between them is proportional to other jobs in the same flow_id
  35          */
  36         if (flow_counter_ratio > flow_weight_ratio) {
  37                 if (td->o.flow_sleep) {
  38                         io_u_quiesce(td);
  39                         usleep(td->o.flow_sleep);
  40                 }
  41
  42                 return 1;
  43         }
  44
  45         /*
  46          * increment flow(shared counter, therefore atomically)
  47          * and job-specific counter
  48          */
  49         atomic_add(&flow->flow_counter, 1);
  50         ++td->flow_counter;
  51
  52         return 0;
  53 }
  54
  55 static struct fio_flow *flow_get(unsigned int id)
  56 {
  57         struct fio_flow *flow = NULL;
  58         struct flist_head *n;
  59
  60         if (!flow_lock)
  61                 return NULL;
  62
  63         fio_sem_down(flow_lock);
  64
  65         flist_for_each(n, flow_list) {
  66                 flow = flist_entry(n, struct fio_flow, list);
  67                 if (flow->id == id)
  68                         break;
  69
  70                 flow = NULL;
  71         }
  72
  73         if (!flow) {
  74                 flow = smalloc(sizeof(*flow));
  75                 if (!flow) {
  76                         fio_sem_up(flow_lock);
  77                         return NULL;
  78                 }
  79                 flow->refs = 0;
  80                 INIT_FLIST_HEAD(&flow->list);
  81                 flow->id = id;
  82                 flow->flow_counter = 1;
  83                 flow->total_weight = 0;
  84
  85                 flist_add_tail(&flow->list, flow_list);
  86         }
  87
  88         flow->refs++;
  89         fio_sem_up(flow_lock);
  90         return flow;
  91 }
  92
  93 static void flow_put(struct fio_flow *flow, unsigned long long flow_counter,
  94                                         unsigned int weight)
  95 {
  96         if (!flow_lock)
  97                 return;
  98
  99         fio_sem_down(flow_lock);
 100
 101         atomic_sub(&flow->flow_counter, flow_counter);
 102         atomic_sub(&flow->total_weight, weight);
 103
 104         if (!--flow->refs) {
 105                 assert(flow->flow_counter == 1);
 106                 flist_del(&flow->list);
 107                 sfree(flow);
 108         }
 109
 110         fio_sem_up(flow_lock);
 111 }
 112
 113 void flow_init_job(struct thread_data *td)
 114 {
 115         if (td->o.flow) {
 116                 td->flow = flow_get(td->o.flow_id);
 117                 td->flow_counter = 0;
 118                 atomic_add(&td->flow->total_weight, td->o.flow);
 119         }
 120 }
 121
 122 void flow_exit_job(struct thread_data *td)
 123 {
 124         if (td->flow) {
 125                 flow_put(td->flow, td->flow_counter, td->o.flow);
 126                 td->flow = NULL;
 127         }
 128 }
 129
 130 void flow_init(void)
 131 {
 132         flow_list = smalloc(sizeof(*flow_list));
 133         if (!flow_list) {
 134                 log_err("fio: smalloc pool exhausted\n");
 135                 return;
 136         }
 137
 138         flow_lock = fio_sem_init(FIO_SEM_UNLOCKED);
 139         if (!flow_lock) {
 140                 log_err("fio: failed to allocate flow lock\n");
 141                 sfree(flow_list);
 142                 return;
 143         }
 144
 145         INIT_FLIST_HEAD(flow_list);
 146 }
 147
 148 void flow_exit(void)
 149 {
 150         if (flow_lock)
 151                 fio_sem_remove(flow_lock);
 152         if (flow_list)
 153                 sfree(flow_list);
 154 }