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12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * General Public License version 2 for more details (a copy is included
14 * in the LICENSE file that accompanied this code).
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17 * version 2 along with this program; If not, see
18 * http://www.gnu.org/licenses/gpl-2.0.html
23 * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
24 * Use is subject to license terms.
26 * Copyright (c) 2012, Intel Corporation.
29 * This file is part of Lustre, http://www.lustre.org/
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32 * libcfs/include/libcfs/libcfs_workitem.h
34 * Author: Isaac Huang <he.h.huang@oracle.com>
35 * Liang Zhen <zhen.liang@sun.com>
37 * A workitems is deferred work with these semantics:
38 * - a workitem always runs in thread context.
39 * - a workitem can be concurrent with other workitems but is strictly
40 * serialized with respect to itself.
41 * - no CPU affinity, a workitem does not necessarily run on the same CPU
42 * that schedules it. However, this might change in the future.
43 * - if a workitem is scheduled again before it has a chance to run, it
45 * - if a workitem is scheduled while it runs, it runs again after it
46 * completes; this ensures that events occurring while other events are
47 * being processed receive due attention. This behavior also allows a
48 * workitem to reschedule itself.
51 * - a workitem can sleep but it should be aware of how that sleep might
53 * - a workitem runs inside a kernel thread so there's no user space to access.
54 * - do not use a workitem if the scheduling latency can't be tolerated.
56 * When wi_action returns non-zero, it means the workitem has either been
57 * freed or reused and workitem scheduler won't touch it any more.
60 #ifndef __LIBCFS_WORKITEM_H__
61 #define __LIBCFS_WORKITEM_H__
65 void cfs_wi_sched_destroy(struct cfs_wi_sched *sched);
66 int cfs_wi_sched_create(char *name, struct cfs_cpt_table *cptab, int cpt,
67 int nthrs, struct cfs_wi_sched **sched_pp);
71 typedef int (*cfs_wi_action_t) (struct cfs_workitem *);
73 /** chain on runq or rerunq */
74 struct list_head wi_list;
75 /** working function */
76 cfs_wi_action_t wi_action;
77 /** arg for working function */
80 unsigned short wi_running:1;
82 unsigned short wi_scheduled:1;
86 cfs_wi_init(struct cfs_workitem *wi, void *data, cfs_wi_action_t action)
88 INIT_LIST_HEAD(&wi->wi_list);
93 wi->wi_action = action;
96 void cfs_wi_schedule(struct cfs_wi_sched *sched, struct cfs_workitem *wi);
97 int cfs_wi_deschedule(struct cfs_wi_sched *sched, struct cfs_workitem *wi);
98 void cfs_wi_exit(struct cfs_wi_sched *sched, struct cfs_workitem *wi);
100 int cfs_wi_startup(void);
101 void cfs_wi_shutdown(void);
103 /** # workitem scheduler loops before reschedule */
104 #define CFS_WI_RESCHED 128
106 #endif /* __LIBCFS_WORKITEM_H__ */