Token-based flow control
[fio.git] / flow.c
CommitLineData
9e684a49
DE
1#include "fio.h"
2#include "mutex.h"
3#include "smalloc.h"
4#include "flist.h"
5
6struct fio_flow {
7 unsigned int refs;
8 struct flist_head list;
9 unsigned int id;
10 long long int flow_counter;
11};
12
13static struct flist_head *flow_list;
14static struct fio_mutex *flow_lock;
15
16int flow_threshold_exceeded(struct thread_data *td)
17{
18 struct fio_flow *flow = td->flow;
19 int sign;
20
21 if (!flow)
22 return 0;
23
24 sign = td->o.flow > 0 ? 1 : -1;
25 if (sign * flow->flow_counter > td->o.flow_watermark) {
26 if (td->o.flow_sleep)
27 usleep(td->o.flow_sleep);
28 return 1;
29 }
30
31 /* No synchronization needed because it doesn't
32 * matter if the flow count is slightly inaccurate */
33 flow->flow_counter += td->o.flow;
34 return 0;
35}
36
37static struct fio_flow *flow_get(unsigned int id)
38{
39 struct fio_flow *flow;
40 struct flist_head *n;
41
42 fio_mutex_down(flow_lock);
43
44 flist_for_each(n, flow_list) {
45 flow = flist_entry(n, struct fio_flow, list);
46 if (flow->id == id)
47 break;
48
49 flow = NULL;
50 }
51
52 if (!flow) {
53 flow = smalloc(sizeof(*flow));
54 flow->refs = 0;
55 INIT_FLIST_HEAD(&flow->list);
56 flow->id = id;
57 flow->flow_counter = 0;
58
59 flist_add_tail(&flow->list, flow_list);
60 }
61
62 flow->refs++;
63 fio_mutex_up(flow_lock);
64 return flow;
65}
66
67static void flow_put(struct fio_flow *flow)
68{
69 fio_mutex_down(flow_lock);
70
71 if (!--flow->refs) {
72 flist_del(&flow->list);
73 sfree(flow);
74 }
75
76 fio_mutex_up(flow_lock);
77}
78
79void flow_init_job(struct thread_data *td)
80{
81 if (td->o.flow)
82 td->flow = flow_get(td->o.flow_id);
83}
84
85void flow_exit_job(struct thread_data *td)
86{
87 if (td->flow) {
88 flow_put(td->flow);
89 td->flow = NULL;
90 }
91}
92
93void flow_init(void)
94{
95 flow_lock = fio_mutex_init(1);
96 flow_list = smalloc(sizeof(*flow_list));
97 INIT_FLIST_HEAD(flow_list);
98}
99
100void flow_exit(void)
101{
102 fio_mutex_remove(flow_lock);
103 sfree(flow_list);
104}