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.sun.com/software/products/lustre/docs/GPLv2.pdf
20 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
21 * CA 95054 USA or visit www.sun.com if you need additional information or
27 * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
28 * Use is subject to license terms.
31 * This file is part of Lustre, http://www.lustre.org/
32 * Lustre is a trademark of Sun Microsystems, Inc.
34 * libcfs/include/libcfs/libcfs_workitem.h
36 * Author: Isaac Huang <he.h.huang@oracle.com>
37 * Liang Zhen <zhen.liang@sun.com>
39 * A workitems is deferred work with these semantics:
40 * - a workitem always runs in thread context.
41 * - a workitem can be concurrent with other workitems but is strictly
42 * serialized with respect to itself.
43 * - no CPU affinity, a workitem does not necessarily run on the same CPU
44 * that schedules it. However, this might change in the future.
45 * - if a workitem is scheduled again before it has a chance to run, it
47 * - if a workitem is scheduled while it runs, it runs again after it
48 * completes; this ensures that events occurring while other events are
49 * being processed receive due attention. This behavior also allows a
50 * workitem to reschedule itself.
53 * - a workitem can sleep but it should be aware of how that sleep might
55 * - a workitem runs inside a kernel thread so there's no user space to access.
56 * - do not use a workitem if the scheduling latency can't be tolerated.
58 * When wi_action returns non-zero, it means the workitem has either been
59 * freed or reused and workitem scheduler won't touch it any more.
62 #ifndef __LIBCFS_WORKITEM_H__
63 #define __LIBCFS_WORKITEM_H__
67 typedef int (*cfs_wi_action_t) (struct cfs_workitem *);
68 typedef struct cfs_workitem {
69 /** chain on runq or rerunq */
71 /** working function */
72 cfs_wi_action_t wi_action;
73 /** arg for working function */
75 /** scheduler id, can be negative */
78 unsigned short wi_running:1;
80 unsigned short wi_scheduled:1;
84 * positive values are reserved as CPU id of future implementation of
85 * per-cpu scheduler, so user can "bind" workitem on specific CPU.
87 #define CFS_WI_SCHED_ANY (-1)
88 #define CFS_WI_SCHED_SERIAL (-2)
91 cfs_wi_init(cfs_workitem_t *wi, void *data,
92 cfs_wi_action_t action, short sched_id)
94 CFS_INIT_LIST_HEAD(&wi->wi_list);
96 wi->wi_sched_id = sched_id;
100 wi->wi_action = action;
103 void cfs_wi_exit(cfs_workitem_t *wi);
104 int cfs_wi_cancel(cfs_workitem_t *wi);
105 void cfs_wi_schedule(cfs_workitem_t *wi);
106 int cfs_wi_startup(void);
107 void cfs_wi_shutdown(void);
110 /** # workitem scheduler loops before reschedule */
111 #define CFS_WI_RESCHED 128
113 int cfs_wi_check_events(void);
116 #endif /* __LIBCFS_WORKITEM_H__ */