107 lines
3.5 KiB
C
107 lines
3.5 KiB
C
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/*
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* GPL HEADER START
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*
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 only,
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License version 2 for more details (a copy is included
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* in the LICENSE file that accompanied this code).
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*
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* You should have received a copy of the GNU General Public License
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* version 2 along with this program; If not, see
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* http://www.gnu.org/licenses/gpl-2.0.html
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*
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* GPL HEADER END
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*/
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/*
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* Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
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* Use is subject to license terms.
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*
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* Copyright (c) 2012, Intel Corporation.
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*/
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/*
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* This file is part of Lustre, http://www.lustre.org/
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* Lustre is a trademark of Sun Microsystems, Inc.
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*
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* libcfs/include/libcfs/libcfs_workitem.h
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*
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* Author: Isaac Huang <he.h.huang@oracle.com>
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* Liang Zhen <zhen.liang@sun.com>
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*
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* A workitems is deferred work with these semantics:
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* - a workitem always runs in thread context.
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* - a workitem can be concurrent with other workitems but is strictly
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* serialized with respect to itself.
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* - no CPU affinity, a workitem does not necessarily run on the same CPU
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* that schedules it. However, this might change in the future.
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* - if a workitem is scheduled again before it has a chance to run, it
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* runs only once.
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* - if a workitem is scheduled while it runs, it runs again after it
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* completes; this ensures that events occurring while other events are
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* being processed receive due attention. This behavior also allows a
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* workitem to reschedule itself.
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*
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* Usage notes:
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* - a workitem can sleep but it should be aware of how that sleep might
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* affect others.
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* - a workitem runs inside a kernel thread so there's no user space to access.
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* - do not use a workitem if the scheduling latency can't be tolerated.
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*
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* When wi_action returns non-zero, it means the workitem has either been
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* freed or reused and workitem scheduler won't touch it any more.
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*/
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#ifndef __LIBCFS_WORKITEM_H__
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#define __LIBCFS_WORKITEM_H__
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struct cfs_wi_sched;
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void cfs_wi_sched_destroy(struct cfs_wi_sched *sched);
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int cfs_wi_sched_create(char *name, struct cfs_cpt_table *cptab, int cpt,
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int nthrs, struct cfs_wi_sched **sched_pp);
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struct cfs_workitem;
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typedef int (*cfs_wi_action_t) (struct cfs_workitem *);
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struct cfs_workitem {
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/** chain on runq or rerunq */
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struct list_head wi_list;
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/** working function */
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cfs_wi_action_t wi_action;
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/** arg for working function */
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void *wi_data;
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/** in running */
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unsigned short wi_running:1;
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/** scheduled */
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unsigned short wi_scheduled:1;
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};
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static inline void
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cfs_wi_init(struct cfs_workitem *wi, void *data, cfs_wi_action_t action)
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{
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INIT_LIST_HEAD(&wi->wi_list);
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wi->wi_running = 0;
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wi->wi_scheduled = 0;
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wi->wi_data = data;
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wi->wi_action = action;
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}
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void cfs_wi_schedule(struct cfs_wi_sched *sched, struct cfs_workitem *wi);
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int cfs_wi_deschedule(struct cfs_wi_sched *sched, struct cfs_workitem *wi);
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void cfs_wi_exit(struct cfs_wi_sched *sched, struct cfs_workitem *wi);
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int cfs_wi_startup(void);
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void cfs_wi_shutdown(void);
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/** # workitem scheduler loops before reschedule */
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#define CFS_WI_RESCHED 128
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#endif /* __LIBCFS_WORKITEM_H__ */
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