1/* 2 * GPL HEADER START 3 * 4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 5 * 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. 9 * 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). 15 * 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 19 * 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 22 * have any questions. 23 * 24 * GPL HEADER END 25 */ 26/* 27 * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved. 28 * Use is subject to license terms. 29 * 30 * Copyright (c) 2012, Intel Corporation. 31 */ 32/* 33 * This file is part of Lustre, http://www.lustre.org/ 34 * Lustre is a trademark of Sun Microsystems, Inc. 35 * 36 * libcfs/include/libcfs/libcfs_workitem.h 37 * 38 * Author: Isaac Huang <he.h.huang@oracle.com> 39 * Liang Zhen <zhen.liang@sun.com> 40 * 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 48 * runs only once. 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. 53 * 54 * Usage notes: 55 * - a workitem can sleep but it should be aware of how that sleep might 56 * affect others. 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. 59 * 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. 62 */ 63 64#ifndef __LIBCFS_WORKITEM_H__ 65#define __LIBCFS_WORKITEM_H__ 66 67struct cfs_wi_sched; 68 69void cfs_wi_sched_destroy(struct cfs_wi_sched *); 70int cfs_wi_sched_create(char *name, struct cfs_cpt_table *cptab, int cpt, 71 int nthrs, struct cfs_wi_sched **); 72 73struct cfs_workitem; 74 75typedef int (*cfs_wi_action_t) (struct cfs_workitem *); 76typedef 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 */ 82 void *wi_data; 83 /** in running */ 84 unsigned short wi_running:1; 85 /** scheduled */ 86 unsigned short wi_scheduled:1; 87} cfs_workitem_t; 88 89static inline void 90cfs_wi_init(cfs_workitem_t *wi, void *data, cfs_wi_action_t action) 91{ 92 INIT_LIST_HEAD(&wi->wi_list); 93 94 wi->wi_running = 0; 95 wi->wi_scheduled = 0; 96 wi->wi_data = data; 97 wi->wi_action = action; 98} 99 100void cfs_wi_schedule(struct cfs_wi_sched *sched, cfs_workitem_t *wi); 101int cfs_wi_deschedule(struct cfs_wi_sched *sched, cfs_workitem_t *wi); 102void cfs_wi_exit(struct cfs_wi_sched *sched, cfs_workitem_t *wi); 103 104int cfs_wi_startup(void); 105void cfs_wi_shutdown(void); 106 107/** # workitem scheduler loops before reschedule */ 108#define CFS_WI_RESCHED 128 109 110#endif /* __LIBCFS_WORKITEM_H__ */ 111