forked from mirrors/linux
35d8ba6629
This changes the worker thread pool to maintain a list of idle threads, avoiding a complex search for a good thread to wake up. Threads have two states: idle - we try to reuse the last thread used in hopes of improving the batching ratios busy - each time a new work item is added to a busy task, the task is rotated to the end of the line. Signed-off-by: Chris Mason <chris.mason@oracle.com>
79 lines
2.5 KiB
C
79 lines
2.5 KiB
C
/*
|
|
* 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 {
|
|
/*
|
|
* only func should be set to the function you want called
|
|
* your work struct is passed as the only arg
|
|
*/
|
|
void (*func)(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 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;
|
|
|
|
/* list with all the work threads */
|
|
struct list_head worker_list;
|
|
struct list_head idle_list;
|
|
|
|
/* lock for finding the next worker thread to queue on */
|
|
spinlock_t lock;
|
|
};
|
|
|
|
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, int max);
|
|
int btrfs_requeue_work(struct btrfs_work *work);
|
|
#endif
|