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Diffstat (limited to 'fs/btrfs/async-thread.h')
| -rw-r--r-- | fs/btrfs/async-thread.h | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/fs/btrfs/async-thread.h b/fs/btrfs/async-thread.h new file mode 100644 index 000000000000..31be4ed8b63e --- /dev/null +++ b/fs/btrfs/async-thread.h @@ -0,0 +1,101 @@ +/* + * Copyright (C) 2007 Oracle. All rights reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public + * License v2 as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public + * License along with this program; if not, write to the + * Free Software Foundation, Inc., 59 Temple Place - Suite 330, + * Boston, MA 021110-1307, USA. + */ + +#ifndef __BTRFS_ASYNC_THREAD_ +#define __BTRFS_ASYNC_THREAD_ + +struct btrfs_worker_thread; + +/* + * This is similar to a workqueue, but it is meant to spread the operations + * across all available cpus instead of just the CPU that was used to + * queue the work. There is also some batching introduced to try and + * cut down on context switches. + * + * By default threads are added on demand up to 2 * the number of cpus. + * Changing struct btrfs_workers->max_workers is one way to prevent + * demand creation of kthreads. + * + * the basic model of these worker threads is to embed a btrfs_work + * structure in your own data struct, and use container_of in a + * work function to get back to your data struct. + */ +struct btrfs_work { + /* + * func should be set to the function you want called + * your work struct is passed as the only arg + * + * ordered_func must be set for work sent to an ordered work queue, + * and it is called to complete a given work item in the same + * order they were sent to the queue. + */ + void (*func)(struct btrfs_work *work); + void (*ordered_func)(struct btrfs_work *work); + void (*ordered_free)(struct btrfs_work *work); + + /* + * flags should be set to zero. It is used to make sure the + * struct is only inserted once into the list. + */ + unsigned long flags; + + /* don't touch these */ + struct btrfs_worker_thread *worker; + struct list_head list; + struct list_head order_list; +}; + +struct btrfs_workers { + /* current number of running workers */ + int num_workers; + + /* max number of workers allowed. changed by btrfs_start_workers */ + int max_workers; + + /* once a worker has this many requests or fewer, it is idle */ + int idle_thresh; + + /* force completions in the order they were queued */ + int ordered; + + /* list with all the work threads. The workers on the idle thread + * may be actively servicing jobs, but they haven't yet hit the + * idle thresh limit above. + */ + struct list_head worker_list; + struct list_head idle_list; + + /* + * when operating in ordered mode, this maintains the list + * of work items waiting for completion + */ + struct list_head order_list; + + /* lock for finding the next worker thread to queue on */ + spinlock_t lock; + + /* extra name for this worker, used for current->name */ + char *name; +}; + +int btrfs_queue_worker(struct btrfs_workers *workers, struct btrfs_work *work); +int btrfs_start_workers(struct btrfs_workers *workers, int num_workers); +int btrfs_stop_workers(struct btrfs_workers *workers); +void btrfs_init_workers(struct btrfs_workers *workers, char *name, int max); +int btrfs_requeue_work(struct btrfs_work *work); +#endif |