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36 * libcfs/include/libcfs/libcfs_workitem.h
38 * Author: Isaac Huang <he.h.huang@oracle.com>
39 * Liang Zhen <zhen.liang@sun.com>
41 * A workitems is deferred work with these semantics:
42 * - a workitem always runs in thread context.
43 * - a workitem can be concurrent with other workitems but is strictly
44 * serialized with respect to itself.
45 * - no CPU affinity, a workitem does not necessarily run on the same CPU
46 * that schedules it. However, this might change in the future.
47 * - if a workitem is scheduled again before it has a chance to run, it
49 * - if a workitem is scheduled while it runs, it runs again after it
50 * completes; this ensures that events occurring while other events are
51 * being processed receive due attention. This behavior also allows a
52 * workitem to reschedule itself.
55 * - a workitem can sleep but it should be aware of how that sleep might
57 * - a workitem runs inside a kernel thread so there's no user space to access.
58 * - do not use a workitem if the scheduling latency can't be tolerated.
60 * When wi_action returns non-zero, it means the workitem has either been
61 * freed or reused and workitem scheduler won't touch it any more.
64 #ifndef __LIBCFS_WORKITEM_H__
65 #define __LIBCFS_WORKITEM_H__
69 void cfs_wi_sched_destroy(struct cfs_wi_sched *);
70 int cfs_wi_sched_create(char *name, struct cfs_cpt_table *cptab, int cpt,
71 int nthrs, struct cfs_wi_sched **);
75 typedef int (*cfs_wi_action_t) (struct cfs_workitem *);
76 typedef struct cfs_workitem {
77 /** chain on runq or rerunq */
78 struct list_head wi_list;
79 /** working function */
80 cfs_wi_action_t wi_action;
81 /** arg for working function */
84 unsigned short wi_running:1;
86 unsigned short wi_scheduled:1;
90 cfs_wi_init(cfs_workitem_t *wi, void *data, cfs_wi_action_t action)
92 INIT_LIST_HEAD(&wi->wi_list);
97 wi->wi_action = action;
100 void cfs_wi_schedule(struct cfs_wi_sched *sched, cfs_workitem_t *wi);
101 int cfs_wi_deschedule(struct cfs_wi_sched *sched, cfs_workitem_t *wi);
102 void cfs_wi_exit(struct cfs_wi_sched *sched, cfs_workitem_t *wi);
104 int cfs_wi_startup(void);
105 void cfs_wi_shutdown(void);
108 /** # workitem scheduler loops before reschedule */
109 #define CFS_WI_RESCHED 128
111 int cfs_wi_check_events(void);
114 #endif /* __LIBCFS_WORKITEM_H__ */