![Qu Wenruo](/assets/img/avatar_default.png)
The original btrfs_workers has thresholding functions to dynamically create or destroy kthreads. Though there is no such function in kernel workqueue because the worker is not created manually, we can still use the workqueue_set_max_active to simulated the behavior, mainly to achieve a better HDD performance by setting a high threshold on submit_workers. (Sadly, no resource can be saved) So in this patch, extra workqueue pending counters are introduced to dynamically change the max active of each btrfs_workqueue_struct, hoping to restore the behavior of the original thresholding function. Also, workqueue_set_max_active use a mutex to protect workqueue_struct, which is not meant to be called too frequently, so a new interval mechanism is applied, that will only call workqueue_set_max_active after a count of work is queued. Hoping to balance both the random and sequence performance on HDD. Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com> Tested-by: David Sterba <dsterba@suse.cz> Signed-off-by: Josef Bacik <jbacik@fb.com>
1025 lines
26 KiB
C
1025 lines
26 KiB
C
/*
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* Copyright (C) 2007 Oracle. All rights reserved.
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* Copyright (C) 2014 Fujitsu. All rights reserved.
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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
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* License v2 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,
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* but 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 for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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#include <linux/kthread.h>
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#include <linux/slab.h>
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#include <linux/list.h>
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#include <linux/spinlock.h>
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#include <linux/freezer.h>
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#include <linux/workqueue.h>
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#include "async-thread.h"
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#define WORK_QUEUED_BIT 0
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#define WORK_DONE_BIT 1
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#define WORK_ORDER_DONE_BIT 2
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#define WORK_HIGH_PRIO_BIT 3
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#define NO_THRESHOLD (-1)
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#define DFT_THRESHOLD (32)
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/*
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* container for the kthread task pointer and the list of pending work
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* One of these is allocated per thread.
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*/
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struct btrfs_worker_thread {
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/* pool we belong to */
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struct btrfs_workers *workers;
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/* list of struct btrfs_work that are waiting for service */
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struct list_head pending;
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struct list_head prio_pending;
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/* list of worker threads from struct btrfs_workers */
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struct list_head worker_list;
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/* kthread */
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struct task_struct *task;
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/* number of things on the pending list */
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atomic_t num_pending;
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/* reference counter for this struct */
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atomic_t refs;
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unsigned long sequence;
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/* protects the pending list. */
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spinlock_t lock;
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/* set to non-zero when this thread is already awake and kicking */
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int working;
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/* are we currently idle */
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int idle;
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};
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static int __btrfs_start_workers(struct btrfs_workers *workers);
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/*
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* btrfs_start_workers uses kthread_run, which can block waiting for memory
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* for a very long time. It will actually throttle on page writeback,
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* and so it may not make progress until after our btrfs worker threads
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* process all of the pending work structs in their queue
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*
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* This means we can't use btrfs_start_workers from inside a btrfs worker
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* thread that is used as part of cleaning dirty memory, which pretty much
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* involves all of the worker threads.
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*
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* Instead we have a helper queue who never has more than one thread
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* where we scheduler thread start operations. This worker_start struct
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* is used to contain the work and hold a pointer to the queue that needs
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* another worker.
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*/
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struct worker_start {
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struct btrfs_work work;
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struct btrfs_workers *queue;
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};
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static void start_new_worker_func(struct btrfs_work *work)
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{
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struct worker_start *start;
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start = container_of(work, struct worker_start, work);
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__btrfs_start_workers(start->queue);
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kfree(start);
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}
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/*
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* helper function to move a thread onto the idle list after it
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* has finished some requests.
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*/
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static void check_idle_worker(struct btrfs_worker_thread *worker)
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{
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if (!worker->idle && atomic_read(&worker->num_pending) <
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worker->workers->idle_thresh / 2) {
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unsigned long flags;
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spin_lock_irqsave(&worker->workers->lock, flags);
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worker->idle = 1;
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/* the list may be empty if the worker is just starting */
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if (!list_empty(&worker->worker_list) &&
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!worker->workers->stopping) {
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list_move(&worker->worker_list,
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&worker->workers->idle_list);
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}
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spin_unlock_irqrestore(&worker->workers->lock, flags);
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}
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}
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/*
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* helper function to move a thread off the idle list after new
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* pending work is added.
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*/
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static void check_busy_worker(struct btrfs_worker_thread *worker)
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{
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if (worker->idle && atomic_read(&worker->num_pending) >=
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worker->workers->idle_thresh) {
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unsigned long flags;
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spin_lock_irqsave(&worker->workers->lock, flags);
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worker->idle = 0;
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if (!list_empty(&worker->worker_list) &&
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!worker->workers->stopping) {
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list_move_tail(&worker->worker_list,
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&worker->workers->worker_list);
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}
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spin_unlock_irqrestore(&worker->workers->lock, flags);
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}
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}
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static void check_pending_worker_creates(struct btrfs_worker_thread *worker)
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{
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struct btrfs_workers *workers = worker->workers;
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struct worker_start *start;
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unsigned long flags;
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rmb();
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if (!workers->atomic_start_pending)
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return;
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start = kzalloc(sizeof(*start), GFP_NOFS);
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if (!start)
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return;
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start->work.func = start_new_worker_func;
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start->queue = workers;
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spin_lock_irqsave(&workers->lock, flags);
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if (!workers->atomic_start_pending)
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goto out;
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workers->atomic_start_pending = 0;
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if (workers->num_workers + workers->num_workers_starting >=
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workers->max_workers)
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goto out;
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workers->num_workers_starting += 1;
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spin_unlock_irqrestore(&workers->lock, flags);
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btrfs_queue_worker(workers->atomic_worker_start, &start->work);
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return;
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out:
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kfree(start);
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spin_unlock_irqrestore(&workers->lock, flags);
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}
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static noinline void run_ordered_completions(struct btrfs_workers *workers,
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struct btrfs_work *work)
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{
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if (!workers->ordered)
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return;
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set_bit(WORK_DONE_BIT, &work->flags);
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spin_lock(&workers->order_lock);
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while (1) {
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if (!list_empty(&workers->prio_order_list)) {
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work = list_entry(workers->prio_order_list.next,
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struct btrfs_work, order_list);
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} else if (!list_empty(&workers->order_list)) {
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work = list_entry(workers->order_list.next,
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struct btrfs_work, order_list);
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} else {
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break;
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}
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if (!test_bit(WORK_DONE_BIT, &work->flags))
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break;
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/* we are going to call the ordered done function, but
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* we leave the work item on the list as a barrier so
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* that later work items that are done don't have their
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* functions called before this one returns
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*/
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if (test_and_set_bit(WORK_ORDER_DONE_BIT, &work->flags))
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break;
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spin_unlock(&workers->order_lock);
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work->ordered_func(work);
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/* now take the lock again and drop our item from the list */
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spin_lock(&workers->order_lock);
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list_del(&work->order_list);
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spin_unlock(&workers->order_lock);
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/*
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* we don't want to call the ordered free functions
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* with the lock held though
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*/
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work->ordered_free(work);
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spin_lock(&workers->order_lock);
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}
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spin_unlock(&workers->order_lock);
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}
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static void put_worker(struct btrfs_worker_thread *worker)
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{
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if (atomic_dec_and_test(&worker->refs))
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kfree(worker);
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}
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static int try_worker_shutdown(struct btrfs_worker_thread *worker)
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{
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int freeit = 0;
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spin_lock_irq(&worker->lock);
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spin_lock(&worker->workers->lock);
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if (worker->workers->num_workers > 1 &&
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worker->idle &&
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!worker->working &&
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!list_empty(&worker->worker_list) &&
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list_empty(&worker->prio_pending) &&
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list_empty(&worker->pending) &&
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atomic_read(&worker->num_pending) == 0) {
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freeit = 1;
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list_del_init(&worker->worker_list);
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worker->workers->num_workers--;
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}
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spin_unlock(&worker->workers->lock);
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spin_unlock_irq(&worker->lock);
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if (freeit)
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put_worker(worker);
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return freeit;
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}
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static struct btrfs_work *get_next_work(struct btrfs_worker_thread *worker,
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struct list_head *prio_head,
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struct list_head *head)
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{
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struct btrfs_work *work = NULL;
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struct list_head *cur = NULL;
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if (!list_empty(prio_head)) {
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cur = prio_head->next;
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goto out;
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}
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smp_mb();
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if (!list_empty(&worker->prio_pending))
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goto refill;
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if (!list_empty(head)) {
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cur = head->next;
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goto out;
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}
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refill:
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spin_lock_irq(&worker->lock);
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list_splice_tail_init(&worker->prio_pending, prio_head);
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list_splice_tail_init(&worker->pending, head);
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if (!list_empty(prio_head))
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cur = prio_head->next;
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else if (!list_empty(head))
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cur = head->next;
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spin_unlock_irq(&worker->lock);
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if (!cur)
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goto out_fail;
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out:
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work = list_entry(cur, struct btrfs_work, list);
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out_fail:
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return work;
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}
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/*
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* main loop for servicing work items
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*/
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static int worker_loop(void *arg)
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{
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struct btrfs_worker_thread *worker = arg;
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struct list_head head;
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struct list_head prio_head;
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struct btrfs_work *work;
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INIT_LIST_HEAD(&head);
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INIT_LIST_HEAD(&prio_head);
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do {
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again:
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while (1) {
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work = get_next_work(worker, &prio_head, &head);
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if (!work)
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break;
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list_del(&work->list);
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clear_bit(WORK_QUEUED_BIT, &work->flags);
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work->worker = worker;
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work->func(work);
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atomic_dec(&worker->num_pending);
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/*
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* unless this is an ordered work queue,
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* 'work' was probably freed by func above.
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*/
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run_ordered_completions(worker->workers, work);
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check_pending_worker_creates(worker);
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cond_resched();
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}
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spin_lock_irq(&worker->lock);
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check_idle_worker(worker);
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if (freezing(current)) {
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worker->working = 0;
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spin_unlock_irq(&worker->lock);
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try_to_freeze();
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} else {
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spin_unlock_irq(&worker->lock);
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if (!kthread_should_stop()) {
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cpu_relax();
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/*
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* we've dropped the lock, did someone else
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* jump_in?
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*/
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smp_mb();
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if (!list_empty(&worker->pending) ||
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!list_empty(&worker->prio_pending))
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continue;
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/*
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* this short schedule allows more work to
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* come in without the queue functions
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* needing to go through wake_up_process()
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*
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* worker->working is still 1, so nobody
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* is going to try and wake us up
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*/
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schedule_timeout(1);
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smp_mb();
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if (!list_empty(&worker->pending) ||
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!list_empty(&worker->prio_pending))
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continue;
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if (kthread_should_stop())
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break;
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/* still no more work?, sleep for real */
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spin_lock_irq(&worker->lock);
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set_current_state(TASK_INTERRUPTIBLE);
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if (!list_empty(&worker->pending) ||
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!list_empty(&worker->prio_pending)) {
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spin_unlock_irq(&worker->lock);
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set_current_state(TASK_RUNNING);
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goto again;
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}
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/*
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* this makes sure we get a wakeup when someone
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* adds something new to the queue
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*/
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worker->working = 0;
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spin_unlock_irq(&worker->lock);
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if (!kthread_should_stop()) {
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schedule_timeout(HZ * 120);
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if (!worker->working &&
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try_worker_shutdown(worker)) {
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return 0;
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}
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}
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}
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__set_current_state(TASK_RUNNING);
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}
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} while (!kthread_should_stop());
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return 0;
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}
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/*
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* this will wait for all the worker threads to shutdown
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*/
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void btrfs_stop_workers(struct btrfs_workers *workers)
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{
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struct list_head *cur;
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struct btrfs_worker_thread *worker;
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int can_stop;
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spin_lock_irq(&workers->lock);
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workers->stopping = 1;
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list_splice_init(&workers->idle_list, &workers->worker_list);
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while (!list_empty(&workers->worker_list)) {
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cur = workers->worker_list.next;
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worker = list_entry(cur, struct btrfs_worker_thread,
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worker_list);
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atomic_inc(&worker->refs);
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workers->num_workers -= 1;
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if (!list_empty(&worker->worker_list)) {
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list_del_init(&worker->worker_list);
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put_worker(worker);
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can_stop = 1;
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} else
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can_stop = 0;
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spin_unlock_irq(&workers->lock);
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if (can_stop)
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kthread_stop(worker->task);
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spin_lock_irq(&workers->lock);
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put_worker(worker);
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}
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spin_unlock_irq(&workers->lock);
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}
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/*
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* simple init on struct btrfs_workers
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*/
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void btrfs_init_workers(struct btrfs_workers *workers, char *name, int max,
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struct btrfs_workers *async_helper)
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{
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workers->num_workers = 0;
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workers->num_workers_starting = 0;
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INIT_LIST_HEAD(&workers->worker_list);
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INIT_LIST_HEAD(&workers->idle_list);
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INIT_LIST_HEAD(&workers->order_list);
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INIT_LIST_HEAD(&workers->prio_order_list);
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spin_lock_init(&workers->lock);
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spin_lock_init(&workers->order_lock);
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workers->max_workers = max;
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workers->idle_thresh = 32;
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workers->name = name;
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workers->ordered = 0;
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workers->atomic_start_pending = 0;
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workers->atomic_worker_start = async_helper;
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workers->stopping = 0;
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}
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/*
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* starts new worker threads. This does not enforce the max worker
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* count in case you need to temporarily go past it.
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*/
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static int __btrfs_start_workers(struct btrfs_workers *workers)
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{
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struct btrfs_worker_thread *worker;
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int ret = 0;
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worker = kzalloc(sizeof(*worker), GFP_NOFS);
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if (!worker) {
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ret = -ENOMEM;
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goto fail;
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}
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INIT_LIST_HEAD(&worker->pending);
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INIT_LIST_HEAD(&worker->prio_pending);
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INIT_LIST_HEAD(&worker->worker_list);
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spin_lock_init(&worker->lock);
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atomic_set(&worker->num_pending, 0);
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atomic_set(&worker->refs, 1);
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worker->workers = workers;
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worker->task = kthread_create(worker_loop, worker,
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"btrfs-%s-%d", workers->name,
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workers->num_workers + 1);
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if (IS_ERR(worker->task)) {
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ret = PTR_ERR(worker->task);
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goto fail;
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}
|
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|
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spin_lock_irq(&workers->lock);
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if (workers->stopping) {
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spin_unlock_irq(&workers->lock);
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ret = -EINVAL;
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goto fail_kthread;
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}
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list_add_tail(&worker->worker_list, &workers->idle_list);
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worker->idle = 1;
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workers->num_workers++;
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workers->num_workers_starting--;
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WARN_ON(workers->num_workers_starting < 0);
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spin_unlock_irq(&workers->lock);
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|
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wake_up_process(worker->task);
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return 0;
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fail_kthread:
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kthread_stop(worker->task);
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fail:
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kfree(worker);
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spin_lock_irq(&workers->lock);
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workers->num_workers_starting--;
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spin_unlock_irq(&workers->lock);
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return ret;
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}
|
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|
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int btrfs_start_workers(struct btrfs_workers *workers)
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{
|
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spin_lock_irq(&workers->lock);
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workers->num_workers_starting++;
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spin_unlock_irq(&workers->lock);
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return __btrfs_start_workers(workers);
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}
|
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|
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/*
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* run through the list and find a worker thread that doesn't have a lot
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* to do right now. This can return null if we aren't yet at the thread
|
|
* count limit and all of the threads are busy.
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*/
|
|
static struct btrfs_worker_thread *next_worker(struct btrfs_workers *workers)
|
|
{
|
|
struct btrfs_worker_thread *worker;
|
|
struct list_head *next;
|
|
int enforce_min;
|
|
|
|
enforce_min = (workers->num_workers + workers->num_workers_starting) <
|
|
workers->max_workers;
|
|
|
|
/*
|
|
* if we find an idle thread, don't move it to the end of the
|
|
* idle list. This improves the chance that the next submission
|
|
* will reuse the same thread, and maybe catch it while it is still
|
|
* working
|
|
*/
|
|
if (!list_empty(&workers->idle_list)) {
|
|
next = workers->idle_list.next;
|
|
worker = list_entry(next, struct btrfs_worker_thread,
|
|
worker_list);
|
|
return worker;
|
|
}
|
|
if (enforce_min || list_empty(&workers->worker_list))
|
|
return NULL;
|
|
|
|
/*
|
|
* if we pick a busy task, move the task to the end of the list.
|
|
* hopefully this will keep things somewhat evenly balanced.
|
|
* Do the move in batches based on the sequence number. This groups
|
|
* requests submitted at roughly the same time onto the same worker.
|
|
*/
|
|
next = workers->worker_list.next;
|
|
worker = list_entry(next, struct btrfs_worker_thread, worker_list);
|
|
worker->sequence++;
|
|
|
|
if (worker->sequence % workers->idle_thresh == 0)
|
|
list_move_tail(next, &workers->worker_list);
|
|
return worker;
|
|
}
|
|
|
|
/*
|
|
* selects a worker thread to take the next job. This will either find
|
|
* an idle worker, start a new worker up to the max count, or just return
|
|
* one of the existing busy workers.
|
|
*/
|
|
static struct btrfs_worker_thread *find_worker(struct btrfs_workers *workers)
|
|
{
|
|
struct btrfs_worker_thread *worker;
|
|
unsigned long flags;
|
|
struct list_head *fallback;
|
|
int ret;
|
|
|
|
spin_lock_irqsave(&workers->lock, flags);
|
|
again:
|
|
worker = next_worker(workers);
|
|
|
|
if (!worker) {
|
|
if (workers->num_workers + workers->num_workers_starting >=
|
|
workers->max_workers) {
|
|
goto fallback;
|
|
} else if (workers->atomic_worker_start) {
|
|
workers->atomic_start_pending = 1;
|
|
goto fallback;
|
|
} else {
|
|
workers->num_workers_starting++;
|
|
spin_unlock_irqrestore(&workers->lock, flags);
|
|
/* we're below the limit, start another worker */
|
|
ret = __btrfs_start_workers(workers);
|
|
spin_lock_irqsave(&workers->lock, flags);
|
|
if (ret)
|
|
goto fallback;
|
|
goto again;
|
|
}
|
|
}
|
|
goto found;
|
|
|
|
fallback:
|
|
fallback = NULL;
|
|
/*
|
|
* we have failed to find any workers, just
|
|
* return the first one we can find.
|
|
*/
|
|
if (!list_empty(&workers->worker_list))
|
|
fallback = workers->worker_list.next;
|
|
if (!list_empty(&workers->idle_list))
|
|
fallback = workers->idle_list.next;
|
|
BUG_ON(!fallback);
|
|
worker = list_entry(fallback,
|
|
struct btrfs_worker_thread, worker_list);
|
|
found:
|
|
/*
|
|
* this makes sure the worker doesn't exit before it is placed
|
|
* onto a busy/idle list
|
|
*/
|
|
atomic_inc(&worker->num_pending);
|
|
spin_unlock_irqrestore(&workers->lock, flags);
|
|
return worker;
|
|
}
|
|
|
|
/*
|
|
* btrfs_requeue_work just puts the work item back on the tail of the list
|
|
* it was taken from. It is intended for use with long running work functions
|
|
* that make some progress and want to give the cpu up for others.
|
|
*/
|
|
void btrfs_requeue_work(struct btrfs_work *work)
|
|
{
|
|
struct btrfs_worker_thread *worker = work->worker;
|
|
unsigned long flags;
|
|
int wake = 0;
|
|
|
|
if (test_and_set_bit(WORK_QUEUED_BIT, &work->flags))
|
|
return;
|
|
|
|
spin_lock_irqsave(&worker->lock, flags);
|
|
if (test_bit(WORK_HIGH_PRIO_BIT, &work->flags))
|
|
list_add_tail(&work->list, &worker->prio_pending);
|
|
else
|
|
list_add_tail(&work->list, &worker->pending);
|
|
atomic_inc(&worker->num_pending);
|
|
|
|
/* by definition we're busy, take ourselves off the idle
|
|
* list
|
|
*/
|
|
if (worker->idle) {
|
|
spin_lock(&worker->workers->lock);
|
|
worker->idle = 0;
|
|
list_move_tail(&worker->worker_list,
|
|
&worker->workers->worker_list);
|
|
spin_unlock(&worker->workers->lock);
|
|
}
|
|
if (!worker->working) {
|
|
wake = 1;
|
|
worker->working = 1;
|
|
}
|
|
|
|
if (wake)
|
|
wake_up_process(worker->task);
|
|
spin_unlock_irqrestore(&worker->lock, flags);
|
|
}
|
|
|
|
void btrfs_set_work_high_prio(struct btrfs_work *work)
|
|
{
|
|
set_bit(WORK_HIGH_PRIO_BIT, &work->flags);
|
|
}
|
|
|
|
/*
|
|
* places a struct btrfs_work into the pending queue of one of the kthreads
|
|
*/
|
|
void btrfs_queue_worker(struct btrfs_workers *workers, struct btrfs_work *work)
|
|
{
|
|
struct btrfs_worker_thread *worker;
|
|
unsigned long flags;
|
|
int wake = 0;
|
|
|
|
/* don't requeue something already on a list */
|
|
if (test_and_set_bit(WORK_QUEUED_BIT, &work->flags))
|
|
return;
|
|
|
|
worker = find_worker(workers);
|
|
if (workers->ordered) {
|
|
/*
|
|
* you're not allowed to do ordered queues from an
|
|
* interrupt handler
|
|
*/
|
|
spin_lock(&workers->order_lock);
|
|
if (test_bit(WORK_HIGH_PRIO_BIT, &work->flags)) {
|
|
list_add_tail(&work->order_list,
|
|
&workers->prio_order_list);
|
|
} else {
|
|
list_add_tail(&work->order_list, &workers->order_list);
|
|
}
|
|
spin_unlock(&workers->order_lock);
|
|
} else {
|
|
INIT_LIST_HEAD(&work->order_list);
|
|
}
|
|
|
|
spin_lock_irqsave(&worker->lock, flags);
|
|
|
|
if (test_bit(WORK_HIGH_PRIO_BIT, &work->flags))
|
|
list_add_tail(&work->list, &worker->prio_pending);
|
|
else
|
|
list_add_tail(&work->list, &worker->pending);
|
|
check_busy_worker(worker);
|
|
|
|
/*
|
|
* avoid calling into wake_up_process if this thread has already
|
|
* been kicked
|
|
*/
|
|
if (!worker->working)
|
|
wake = 1;
|
|
worker->working = 1;
|
|
|
|
if (wake)
|
|
wake_up_process(worker->task);
|
|
spin_unlock_irqrestore(&worker->lock, flags);
|
|
}
|
|
|
|
struct __btrfs_workqueue_struct {
|
|
struct workqueue_struct *normal_wq;
|
|
/* List head pointing to ordered work list */
|
|
struct list_head ordered_list;
|
|
|
|
/* Spinlock for ordered_list */
|
|
spinlock_t list_lock;
|
|
|
|
/* Thresholding related variants */
|
|
atomic_t pending;
|
|
int max_active;
|
|
int current_max;
|
|
int thresh;
|
|
unsigned int count;
|
|
spinlock_t thres_lock;
|
|
};
|
|
|
|
struct btrfs_workqueue_struct {
|
|
struct __btrfs_workqueue_struct *normal;
|
|
struct __btrfs_workqueue_struct *high;
|
|
};
|
|
|
|
static inline struct __btrfs_workqueue_struct
|
|
*__btrfs_alloc_workqueue(char *name, int flags, int max_active, int thresh)
|
|
{
|
|
struct __btrfs_workqueue_struct *ret = kzalloc(sizeof(*ret), GFP_NOFS);
|
|
|
|
if (unlikely(!ret))
|
|
return NULL;
|
|
|
|
ret->max_active = max_active;
|
|
atomic_set(&ret->pending, 0);
|
|
if (thresh == 0)
|
|
thresh = DFT_THRESHOLD;
|
|
/* For low threshold, disabling threshold is a better choice */
|
|
if (thresh < DFT_THRESHOLD) {
|
|
ret->current_max = max_active;
|
|
ret->thresh = NO_THRESHOLD;
|
|
} else {
|
|
ret->current_max = 1;
|
|
ret->thresh = thresh;
|
|
}
|
|
|
|
if (flags & WQ_HIGHPRI)
|
|
ret->normal_wq = alloc_workqueue("%s-%s-high", flags,
|
|
ret->max_active,
|
|
"btrfs", name);
|
|
else
|
|
ret->normal_wq = alloc_workqueue("%s-%s", flags,
|
|
ret->max_active, "btrfs",
|
|
name);
|
|
if (unlikely(!ret->normal_wq)) {
|
|
kfree(ret);
|
|
return NULL;
|
|
}
|
|
|
|
INIT_LIST_HEAD(&ret->ordered_list);
|
|
spin_lock_init(&ret->list_lock);
|
|
spin_lock_init(&ret->thres_lock);
|
|
return ret;
|
|
}
|
|
|
|
static inline void
|
|
__btrfs_destroy_workqueue(struct __btrfs_workqueue_struct *wq);
|
|
|
|
struct btrfs_workqueue_struct *btrfs_alloc_workqueue(char *name,
|
|
int flags,
|
|
int max_active,
|
|
int thresh)
|
|
{
|
|
struct btrfs_workqueue_struct *ret = kzalloc(sizeof(*ret), GFP_NOFS);
|
|
|
|
if (unlikely(!ret))
|
|
return NULL;
|
|
|
|
ret->normal = __btrfs_alloc_workqueue(name, flags & ~WQ_HIGHPRI,
|
|
max_active, thresh);
|
|
if (unlikely(!ret->normal)) {
|
|
kfree(ret);
|
|
return NULL;
|
|
}
|
|
|
|
if (flags & WQ_HIGHPRI) {
|
|
ret->high = __btrfs_alloc_workqueue(name, flags, max_active,
|
|
thresh);
|
|
if (unlikely(!ret->high)) {
|
|
__btrfs_destroy_workqueue(ret->normal);
|
|
kfree(ret);
|
|
return NULL;
|
|
}
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Hook for threshold which will be called in btrfs_queue_work.
|
|
* This hook WILL be called in IRQ handler context,
|
|
* so workqueue_set_max_active MUST NOT be called in this hook
|
|
*/
|
|
static inline void thresh_queue_hook(struct __btrfs_workqueue_struct *wq)
|
|
{
|
|
if (wq->thresh == NO_THRESHOLD)
|
|
return;
|
|
atomic_inc(&wq->pending);
|
|
}
|
|
|
|
/*
|
|
* Hook for threshold which will be called before executing the work,
|
|
* This hook is called in kthread content.
|
|
* So workqueue_set_max_active is called here.
|
|
*/
|
|
static inline void thresh_exec_hook(struct __btrfs_workqueue_struct *wq)
|
|
{
|
|
int new_max_active;
|
|
long pending;
|
|
int need_change = 0;
|
|
|
|
if (wq->thresh == NO_THRESHOLD)
|
|
return;
|
|
|
|
atomic_dec(&wq->pending);
|
|
spin_lock(&wq->thres_lock);
|
|
/*
|
|
* Use wq->count to limit the calling frequency of
|
|
* workqueue_set_max_active.
|
|
*/
|
|
wq->count++;
|
|
wq->count %= (wq->thresh / 4);
|
|
if (!wq->count)
|
|
goto out;
|
|
new_max_active = wq->current_max;
|
|
|
|
/*
|
|
* pending may be changed later, but it's OK since we really
|
|
* don't need it so accurate to calculate new_max_active.
|
|
*/
|
|
pending = atomic_read(&wq->pending);
|
|
if (pending > wq->thresh)
|
|
new_max_active++;
|
|
if (pending < wq->thresh / 2)
|
|
new_max_active--;
|
|
new_max_active = clamp_val(new_max_active, 1, wq->max_active);
|
|
if (new_max_active != wq->current_max) {
|
|
need_change = 1;
|
|
wq->current_max = new_max_active;
|
|
}
|
|
out:
|
|
spin_unlock(&wq->thres_lock);
|
|
|
|
if (need_change) {
|
|
workqueue_set_max_active(wq->normal_wq, wq->current_max);
|
|
}
|
|
}
|
|
|
|
static void run_ordered_work(struct __btrfs_workqueue_struct *wq)
|
|
{
|
|
struct list_head *list = &wq->ordered_list;
|
|
struct btrfs_work_struct *work;
|
|
spinlock_t *lock = &wq->list_lock;
|
|
unsigned long flags;
|
|
|
|
while (1) {
|
|
spin_lock_irqsave(lock, flags);
|
|
if (list_empty(list))
|
|
break;
|
|
work = list_entry(list->next, struct btrfs_work_struct,
|
|
ordered_list);
|
|
if (!test_bit(WORK_DONE_BIT, &work->flags))
|
|
break;
|
|
|
|
/*
|
|
* we are going to call the ordered done function, but
|
|
* we leave the work item on the list as a barrier so
|
|
* that later work items that are done don't have their
|
|
* functions called before this one returns
|
|
*/
|
|
if (test_and_set_bit(WORK_ORDER_DONE_BIT, &work->flags))
|
|
break;
|
|
spin_unlock_irqrestore(lock, flags);
|
|
work->ordered_func(work);
|
|
|
|
/* now take the lock again and drop our item from the list */
|
|
spin_lock_irqsave(lock, flags);
|
|
list_del(&work->ordered_list);
|
|
spin_unlock_irqrestore(lock, flags);
|
|
|
|
/*
|
|
* we don't want to call the ordered free functions
|
|
* with the lock held though
|
|
*/
|
|
work->ordered_free(work);
|
|
}
|
|
spin_unlock_irqrestore(lock, flags);
|
|
}
|
|
|
|
static void normal_work_helper(struct work_struct *arg)
|
|
{
|
|
struct btrfs_work_struct *work;
|
|
struct __btrfs_workqueue_struct *wq;
|
|
int need_order = 0;
|
|
|
|
work = container_of(arg, struct btrfs_work_struct, normal_work);
|
|
/*
|
|
* We should not touch things inside work in the following cases:
|
|
* 1) after work->func() if it has no ordered_free
|
|
* Since the struct is freed in work->func().
|
|
* 2) after setting WORK_DONE_BIT
|
|
* The work may be freed in other threads almost instantly.
|
|
* So we save the needed things here.
|
|
*/
|
|
if (work->ordered_func)
|
|
need_order = 1;
|
|
wq = work->wq;
|
|
|
|
thresh_exec_hook(wq);
|
|
work->func(work);
|
|
if (need_order) {
|
|
set_bit(WORK_DONE_BIT, &work->flags);
|
|
run_ordered_work(wq);
|
|
}
|
|
}
|
|
|
|
void btrfs_init_work(struct btrfs_work_struct *work,
|
|
void (*func)(struct btrfs_work_struct *),
|
|
void (*ordered_func)(struct btrfs_work_struct *),
|
|
void (*ordered_free)(struct btrfs_work_struct *))
|
|
{
|
|
work->func = func;
|
|
work->ordered_func = ordered_func;
|
|
work->ordered_free = ordered_free;
|
|
INIT_WORK(&work->normal_work, normal_work_helper);
|
|
INIT_LIST_HEAD(&work->ordered_list);
|
|
work->flags = 0;
|
|
}
|
|
|
|
static inline void __btrfs_queue_work(struct __btrfs_workqueue_struct *wq,
|
|
struct btrfs_work_struct *work)
|
|
{
|
|
unsigned long flags;
|
|
|
|
work->wq = wq;
|
|
thresh_queue_hook(wq);
|
|
if (work->ordered_func) {
|
|
spin_lock_irqsave(&wq->list_lock, flags);
|
|
list_add_tail(&work->ordered_list, &wq->ordered_list);
|
|
spin_unlock_irqrestore(&wq->list_lock, flags);
|
|
}
|
|
queue_work(wq->normal_wq, &work->normal_work);
|
|
}
|
|
|
|
void btrfs_queue_work(struct btrfs_workqueue_struct *wq,
|
|
struct btrfs_work_struct *work)
|
|
{
|
|
struct __btrfs_workqueue_struct *dest_wq;
|
|
|
|
if (test_bit(WORK_HIGH_PRIO_BIT, &work->flags) && wq->high)
|
|
dest_wq = wq->high;
|
|
else
|
|
dest_wq = wq->normal;
|
|
__btrfs_queue_work(dest_wq, work);
|
|
}
|
|
|
|
static inline void
|
|
__btrfs_destroy_workqueue(struct __btrfs_workqueue_struct *wq)
|
|
{
|
|
destroy_workqueue(wq->normal_wq);
|
|
kfree(wq);
|
|
}
|
|
|
|
void btrfs_destroy_workqueue(struct btrfs_workqueue_struct *wq)
|
|
{
|
|
if (!wq)
|
|
return;
|
|
if (wq->high)
|
|
__btrfs_destroy_workqueue(wq->high);
|
|
__btrfs_destroy_workqueue(wq->normal);
|
|
}
|
|
|
|
void btrfs_workqueue_set_max(struct btrfs_workqueue_struct *wq, int max)
|
|
{
|
|
wq->normal->max_active = max;
|
|
if (wq->high)
|
|
wq->high->max_active = max;
|
|
}
|
|
|
|
void btrfs_set_work_high_priority(struct btrfs_work_struct *work)
|
|
{
|
|
set_bit(WORK_HIGH_PRIO_BIT, &work->flags);
|
|
}
|