4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 only,
8 * as published by the Free Software Foundation.
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
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).
16 * You should have received a copy of the GNU General Public License
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/
31 * libcfs/include/libcfs/libcfs_workitem.h
33 * Author: Isaac Huang <he.h.huang@oracle.com>
34 * Liang Zhen <zhen.liang@sun.com>
36 * A workitems is deferred work with these semantics:
37 * - a workitem always runs in thread context.
38 * - a workitem can be concurrent with other workitems but is strictly
39 * serialized with respect to itself.
40 * - no CPU affinity, a workitem does not necessarily run on the same CPU
41 * that schedules it. However, this might change in the future.
42 * - if a workitem is scheduled again before it has a chance to run, it
44 * - if a workitem is scheduled while it runs, it runs again after it
45 * completes; this ensures that events occurring while other events are
46 * being processed receive due attention. This behavior also allows a
47 * workitem to reschedule itself.
50 * - a workitem can sleep but it should be aware of how that sleep might
52 * - a workitem runs inside a kernel thread so there's no user space to access.
53 * - do not use a workitem if the scheduling latency can't be tolerated.
55 * When wi_action returns non-zero, it means the workitem has either been
56 * freed or reused and workitem scheduler won't touch it any more.
59 #ifndef __LIBCFS_WORKITEM_H__
60 #define __LIBCFS_WORKITEM_H__
64 void cfs_wi_sched_destroy(struct cfs_wi_sched *);
65 int cfs_wi_sched_create(char *name, struct cfs_cpt_table *cptab, int cpt,
66 int nthrs, struct cfs_wi_sched **);
70 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;
78 unsigned short wi_running:1;
80 unsigned short wi_scheduled:1;
84 cfs_wi_init(struct cfs_workitem *wi, cfs_wi_action_t action)
86 INIT_LIST_HEAD(&wi->wi_list);
90 wi->wi_action = action;
93 void cfs_wi_schedule(struct cfs_wi_sched *sched, struct cfs_workitem *wi);
94 int cfs_wi_deschedule(struct cfs_wi_sched *sched, struct cfs_workitem *wi);
95 void cfs_wi_exit(struct cfs_wi_sched *sched, struct cfs_workitem *wi);
97 int cfs_wi_startup(void);
98 void cfs_wi_shutdown(void);
100 /** # workitem scheduler loops before reschedule */
101 #define CFS_WI_RESCHED 128
103 #endif /* __LIBCFS_WORKITEM_H__ */