| Chris Mason | 8b71284 | 2008-06-11 16:50:36 -0400 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright (C) 2007 Oracle. All rights reserved. |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or |
| 5 | * modify it under the terms of the GNU General Public |
| 6 | * License v2 as published by the Free Software Foundation. |
| 7 | * |
| 8 | * This program is distributed in the hope that it will be useful, |
| 9 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 10 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 11 | * General Public License for more details. |
| 12 | * |
| 13 | * You should have received a copy of the GNU General Public |
| 14 | * License along with this program; if not, write to the |
| 15 | * Free Software Foundation, Inc., 59 Temple Place - Suite 330, |
| 16 | * Boston, MA 021110-1307, USA. |
| 17 | */ |
| 18 | |
| 19 | #ifndef __BTRFS_ASYNC_THREAD_ |
| 20 | #define __BTRFS_ASYNC_THREAD_ |
| 21 | |
| 22 | struct btrfs_worker_thread; |
| 23 | |
| 24 | /* |
| 25 | * This is similar to a workqueue, but it is meant to spread the operations |
| 26 | * across all available cpus instead of just the CPU that was used to |
| 27 | * queue the work. There is also some batching introduced to try and |
| 28 | * cut down on context switches. |
| 29 | * |
| 30 | * By default threads are added on demand up to 2 * the number of cpus. |
| 31 | * Changing struct btrfs_workers->max_workers is one way to prevent |
| 32 | * demand creation of kthreads. |
| 33 | * |
| 34 | * the basic model of these worker threads is to embed a btrfs_work |
| 35 | * structure in your own data struct, and use container_of in a |
| 36 | * work function to get back to your data struct. |
| 37 | */ |
| 38 | struct btrfs_work { |
| 39 | /* |
| 40 | * only func should be set to the function you want called |
| 41 | * your work struct is passed as the only arg |
| 42 | */ |
| 43 | void (*func)(struct btrfs_work *work); |
| 44 | |
| 45 | /* |
| 46 | * flags should be set to zero. It is used to make sure the |
| 47 | * struct is only inserted once into the list. |
| 48 | */ |
| 49 | unsigned long flags; |
| 50 | |
| 51 | /* don't touch these */ |
| 52 | struct btrfs_worker_thread *worker; |
| 53 | struct list_head list; |
| 54 | }; |
| 55 | |
| 56 | struct btrfs_workers { |
| 57 | /* current number of running workers */ |
| 58 | int num_workers; |
| 59 | |
| 60 | /* max number of workers allowed. changed by btrfs_start_workers */ |
| 61 | int max_workers; |
| 62 | |
| 63 | /* list with all the work threads */ |
| 64 | struct list_head worker_list; |
| 65 | |
| 66 | /* the last worker thread to have something queued */ |
| 67 | struct btrfs_worker_thread *last; |
| 68 | |
| 69 | /* lock for finding the next worker thread to queue on */ |
| 70 | spinlock_t lock; |
| 71 | }; |
| 72 | |
| 73 | int btrfs_queue_worker(struct btrfs_workers *workers, struct btrfs_work *work); |
| 74 | int btrfs_start_workers(struct btrfs_workers *workers, int num_workers); |
| 75 | int btrfs_stop_workers(struct btrfs_workers *workers); |
| 76 | void btrfs_init_workers(struct btrfs_workers *workers, int max); |
| 77 | int btrfs_requeue_work(struct btrfs_work *work); |
| 78 | #endif |