12e22c5e4b
Make the slow work pool configurable through /proc/sys/kernel/slow-work.
(*) /proc/sys/kernel/slow-work/min-threads
The minimum number of threads that should be in the pool as long as it is
in use. This may be anywhere between 2 and max-threads.
(*) /proc/sys/kernel/slow-work/max-threads
The maximum number of threads that should in the pool. This may be
anywhere between min-threads and 255 or NR_CPUS * 2, whichever is greater.
(*) /proc/sys/kernel/slow-work/vslow-percentage
The percentage of active threads in the pool that may be used to execute
very slow work items. This may be between 1 and 99. The resultant number
is bounded to between 1 and one fewer than the number of active threads.
This ensures there is always at least one thread that can process very
slow work items, and always at least one thread that won't.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
94 lines
2.5 KiB
C
94 lines
2.5 KiB
C
/* Worker thread pool for slow items, such as filesystem lookups or mkdirs
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*
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* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public Licence
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* as published by the Free Software Foundation; either version
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* 2 of the Licence, or (at your option) any later version.
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*/
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#ifndef _LINUX_SLOW_WORK_H
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#define _LINUX_SLOW_WORK_H
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#ifdef CONFIG_SLOW_WORK
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#include <linux/sysctl.h>
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struct slow_work;
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/*
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* The operations used to support slow work items
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*/
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struct slow_work_ops {
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/* get a ref on a work item
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* - return 0 if successful, -ve if not
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*/
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int (*get_ref)(struct slow_work *work);
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/* discard a ref to a work item */
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void (*put_ref)(struct slow_work *work);
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/* execute a work item */
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void (*execute)(struct slow_work *work);
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};
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/*
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* A slow work item
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* - A reference is held on the parent object by the thread pool when it is
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* queued
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*/
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struct slow_work {
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unsigned long flags;
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#define SLOW_WORK_PENDING 0 /* item pending (further) execution */
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#define SLOW_WORK_EXECUTING 1 /* item currently executing */
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#define SLOW_WORK_ENQ_DEFERRED 2 /* item enqueue deferred */
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#define SLOW_WORK_VERY_SLOW 3 /* item is very slow */
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const struct slow_work_ops *ops; /* operations table for this item */
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struct list_head link; /* link in queue */
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};
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/**
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* slow_work_init - Initialise a slow work item
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* @work: The work item to initialise
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* @ops: The operations to use to handle the slow work item
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*
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* Initialise a slow work item.
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*/
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static inline void slow_work_init(struct slow_work *work,
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const struct slow_work_ops *ops)
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{
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work->flags = 0;
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work->ops = ops;
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INIT_LIST_HEAD(&work->link);
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}
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/**
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* slow_work_init - Initialise a very slow work item
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* @work: The work item to initialise
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* @ops: The operations to use to handle the slow work item
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*
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* Initialise a very slow work item. This item will be restricted such that
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* only a certain number of the pool threads will be able to execute items of
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* this type.
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*/
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static inline void vslow_work_init(struct slow_work *work,
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const struct slow_work_ops *ops)
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{
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work->flags = 1 << SLOW_WORK_VERY_SLOW;
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work->ops = ops;
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INIT_LIST_HEAD(&work->link);
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}
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extern int slow_work_enqueue(struct slow_work *work);
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extern int slow_work_register_user(void);
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extern void slow_work_unregister_user(void);
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#ifdef CONFIG_SYSCTL
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extern ctl_table slow_work_sysctls[];
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#endif
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#endif /* CONFIG_SLOW_WORK */
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#endif /* _LINUX_SLOW_WORK_H */
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