diff options
| -rw-r--r-- | Documentation/slow-work.txt | 322 | ||||
| -rw-r--r-- | include/linux/slow-work.h | 163 | ||||
| -rw-r--r-- | init/Kconfig | 24 | ||||
| -rw-r--r-- | kernel/Makefile | 2 | ||||
| -rw-r--r-- | kernel/slow-work-debugfs.c | 227 | ||||
| -rw-r--r-- | kernel/slow-work.c | 1068 | ||||
| -rw-r--r-- | kernel/slow-work.h | 72 | ||||
| -rw-r--r-- | kernel/sysctl.c | 8 |
8 files changed, 0 insertions, 1886 deletions
diff --git a/Documentation/slow-work.txt b/Documentation/slow-work.txt deleted file mode 100644 index 9dbf4470c7e..00000000000 --- a/Documentation/slow-work.txt +++ /dev/null @@ -1,322 +0,0 @@ - ==================================== - SLOW WORK ITEM EXECUTION THREAD POOL - ==================================== - -By: David Howells <dhowells@redhat.com> - -The slow work item execution thread pool is a pool of threads for performing -things that take a relatively long time, such as making mkdir calls. -Typically, when processing something, these items will spend a lot of time -blocking a thread on I/O, thus making that thread unavailable for doing other -work. - -The standard workqueue model is unsuitable for this class of work item as that -limits the owner to a single thread or a single thread per CPU. For some -tasks, however, more threads - or fewer - are required. - -There is just one pool per system. It contains no threads unless something -wants to use it - and that something must register its interest first. When -the pool is active, the number of threads it contains is dynamic, varying -between a maximum and minimum setting, depending on the load. - - -==================== -CLASSES OF WORK ITEM -==================== - -This pool support two classes of work items: - - (*) Slow work items. - - (*) Very slow work items. - -The former are expected to finish much quicker than the latter. - -An operation of the very slow class may do a batch combination of several -lookups, mkdirs, and a create for instance. - -An operation of the ordinarily slow class may, for example, write stuff or -expand files, provided the time taken to do so isn't too long. - -Operations of both types may sleep during execution, thus tying up the thread -loaned to it. - -A further class of work item is available, based on the slow work item class: - - (*) Delayed slow work items. - -These are slow work items that have a timer to defer queueing of the item for -a while. - - -THREAD-TO-CLASS ALLOCATION --------------------------- - -Not all the threads in the pool are available to work on very slow work items. -The number will be between one and one fewer than the number of active threads. -This is configurable (see the "Pool Configuration" section). - -All the threads are available to work on ordinarily slow work items, but a -percentage of the threads will prefer to work on very slow work items. - -The configuration ensures that at least one thread will be available to work on -very slow work items, and at least one thread will be available that won't work -on very slow work items at all. - - -===================== -USING SLOW WORK ITEMS -===================== - -Firstly, a module or subsystem wanting to make use of slow work items must -register its interest: - - int ret = slow_work_register_user(struct module *module); - -This will return 0 if successful, or a -ve error upon failure. The module -pointer should be the module interested in using this facility (almost -certainly THIS_MODULE). - - -Slow work items may then be set up by: - - (1) Declaring a slow_work struct type variable: - - #include <linux/slow-work.h> - - struct slow_work myitem; - - (2) Declaring the operations to be used for this item: - - struct slow_work_ops myitem_ops = { - .get_ref = myitem_get_ref, - .put_ref = myitem_put_ref, - .execute = myitem_execute, - }; - - [*] For a description of the ops, see section "Item Operations". - - (3) Initialising the item: - - slow_work_init(&myitem, &myitem_ops); - - or: - - delayed_slow_work_init(&myitem, &myitem_ops); - - or: - - vslow_work_init(&myitem, &myitem_ops); - - depending on its class. - -A suitably set up work item can then be enqueued for processing: - - int ret = slow_work_enqueue(&myitem); - -This will return a -ve error if the thread pool is unable to gain a reference -on the item, 0 otherwise, or (for delayed work): - - int ret = delayed_slow_work_enqueue(&myitem, my_jiffy_delay); - - -The items are reference counted, so there ought to be no need for a flush -operation. But as the reference counting is optional, means to cancel -existing work items are also included: - - cancel_slow_work(&myitem); - cancel_delayed_slow_work(&myitem); - -can be used to cancel pending work. The above cancel function waits for -existing work to have been executed (or prevent execution of them, depending -on timing). - - -When all a module's slow work items have been processed, and the -module has no further interest in the facility, it should unregister its -interest: - - slow_work_unregister_user(struct module *module); - -The module pointer is used to wait for all outstanding work items for that -module before completing the unregistration. This prevents the put_ref() code -from being taken away before it completes. module should almost certainly be -THIS_MODULE. - - -================ -HELPER FUNCTIONS -================ - -The slow-work facility provides a function by which it can be determined -whether or not an item is queued for later execution: - - bool queued = slow_work_is_queued(struct slow_work *work); - -If it returns false, then the item is not on the queue (it may be executing -with a requeue pending). This can be used to work out whether an item on which -another depends is on the queue, thus allowing a dependent item to be queued -after it. - -If the above shows an item on which another depends not to be queued, then the -owner of the dependent item might need to wait. However, to avoid locking up -the threads unnecessarily be sleeping in them, it can make sense under some -circumstances to return the work item to the queue, thus deferring it until -some other items have had a chance to make use of the yielded thread. - -To yield a thread and defer an item, the work function should simply enqueue -the work item again and return. However, this doesn't work if there's nothing -actually on the queue, as the thread just vacated will jump straight back into -the item's work function, thus busy waiting on a CPU. - -Instead, the item should use the thread to wait for the dependency to go away, -but rather than using schedule() or schedule_timeout() to sleep, it should use -the following function: - - bool requeue = slow_work_sleep_till_thread_needed( - struct slow_work *work, - signed long *_timeout); - -This will add a second wait and then sleep, such that it will be woken up if -either something appears on the queue that could usefully make use of the -thread - and behind which this item can be queued, or if the event the caller -set up to wait for happens. True will be returned if something else appeared -on the queue and this work function should perhaps return, of false if -something else woke it up. The timeout is as for schedule_timeout(). - -For example: - - wq = bit_waitqueue(&my_flags, MY_BIT); - init_wait(&wait); - requeue = false; - do { - prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE); - if (!test_bit(MY_BIT, &my_flags)) - break; - requeue = slow_work_sleep_till_thread_needed(&my_work, - &timeout); - } while (timeout > 0 && !requeue); - finish_wait(wq, &wait); - if (!test_bit(MY_BIT, &my_flags) - goto do_my_thing; - if (requeue) - return; // to slow_work - - -=============== -ITEM OPERATIONS -=============== - -Each work item requires a table of operations of type struct slow_work_ops. -Only ->execute() is required; the getting and putting of a reference and the -describing of an item are all optional. - - (*) Get a reference on an item: - - int (*get_ref)(struct slow_work *work); - - This allows the thread pool to attempt to pin an item by getting a - reference on it. This function should return 0 if the reference was - granted, or a -ve error otherwise. If an error is returned, - slow_work_enqueue() will fail. - - The reference is held whilst the item is queued and whilst it is being - executed. The item may then be requeued with the same reference held, or - the reference will be released. - - (*) Release a reference on an item: - - void (*put_ref)(struct slow_work *work); - - This allows the thread pool to unpin an item by releasing the reference on - it. The thread pool will not touch the item again once this has been - called. - - (*) Execute an item: - - void (*execute)(struct slow_work *work); - - This should perform the work required of the item. It may sleep, it may - perform disk I/O and it may wait for locks. - - (*) View an item through /proc: - - void (*desc)(struct slow_work *work, struct seq_file *m); - - If supplied, this should print to 'm' a small string describing the work - the item is to do. This should be no more than about 40 characters, and - shouldn't include a newline character. - - See the 'Viewing executing and queued items' section below. - - -================== -POOL CONFIGURATION -================== - -The slow-work thread pool has a number of configurables: - - (*) /proc/sys/kernel/slow-work/min-threads - - The minimum number of threads that should be in the pool whilst 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. - - -================================== -VIEWING EXECUTING AND QUEUED ITEMS -================================== - -If CONFIG_SLOW_WORK_DEBUG is enabled, a debugfs file is made available: - - /sys/kernel/debug/slow_work/runqueue - -through which the list of work items being executed and the queues of items to -be executed may be viewed. The owner of a work item is given the chance to -add some information of its own. - -The contents look something like the following: - - THR PID ITEM ADDR FL MARK DESC - === ===== ================ == ===== ========== - 0 3005 ffff880023f52348 a 952ms FSC: OBJ17d3: LOOK - 1 3006 ffff880024e33668 2 160ms FSC: OBJ17e5 OP60d3b: Write1/Store fl=2 - 2 3165 ffff8800296dd180 a 424ms FSC: OBJ17e4: LOOK - 3 4089 ffff8800262c8d78 a 212ms FSC: OBJ17ea: CRTN - 4 4090 ffff88002792bed8 2 388ms FSC: OBJ17e8 OP60d36: Write1/Store fl=2 - 5 4092 ffff88002a0ef308 2 388ms FSC: OBJ17e7 OP60d2e: Write1/Store fl=2 - 6 4094 ffff88002abaf4b8 2 132ms FSC: OBJ17e2 OP60d4e: Write1/Store fl=2 - 7 4095 ffff88002bb188e0 a 388ms FSC: OBJ17e9: CRTN - vsq - ffff880023d99668 1 308ms FSC: OBJ17e0 OP60f91: Write1/EnQ fl=2 - vsq - ffff8800295d1740 1 212ms FSC: OBJ16be OP4d4b6: Write1/EnQ fl=2 - vsq - ffff880025ba3308 1 160ms FSC: OBJ179a OP58dec: Write1/EnQ fl=2 - vsq - ffff880024ec83e0 1 160ms FSC: OBJ17ae OP599f2: Write1/EnQ fl=2 - vsq - ffff880026618e00 1 160ms FSC: OBJ17e6 OP60d33: Write1/EnQ fl=2 - vsq - ffff880025a2a4b8 1 132ms FSC: OBJ16a2 OP4d583: Write1/EnQ fl=2 - vsq - ffff880023cbe6d8 9 212ms FSC: OBJ17eb: LOOK - vsq - ffff880024d37590 9 212ms FSC: OBJ17ec: LOOK - vsq - ffff880027746cb0 9 212ms FSC: OBJ17ed: LOOK - vsq - ffff880024d37ae8 9 212ms FSC: OBJ17ee: LOOK - vsq - ffff880024d37cb0 9 212ms FSC: OBJ17ef: LOOK - vsq - ffff880025036550 9 212ms FSC: OBJ17f0: LOOK - vsq - ffff8800250368e0 9 212ms FSC: OBJ17f1: LOOK - vsq - ffff880025036aa8 9 212ms FSC: OBJ17f2: LOOK - -In the 'THR' column, executing items show the thread they're occupying and -queued threads indicate which queue they're on. 'PID' shows the process ID of -a slow-work thread that's executing something. 'FL' shows the work item flags. -'MARK' indicates how long since an item was queued or began executing. Lastly, -the 'DESC' column permits the owner of an item to give some information. - diff --git a/include/linux/slow-work.h b/include/linux/slow-work.h deleted file mode 100644 index 13337bf6c3f..00000000000 --- a/include/linux/slow-work.h +++ /dev/null @@ -1,163 +0,0 @@ -/* Worker thread pool for slow items, such as filesystem lookups or mkdirs - * - * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved. - * Written by David Howells (dhowells@redhat.com) - * - * This program is free software; you can redistribute it and/or - * modify it under the terms of the GNU General Public Licence - * as published by the Free Software Foundation; either version - * 2 of the Licence, or (at your option) any later version. - * - * See Documentation/slow-work.txt - */ - -#ifndef _LINUX_SLOW_WORK_H -#define _LINUX_SLOW_WORK_H - -#ifdef CONFIG_SLOW_WORK - -#include <linux/sysctl.h> -#include <linux/timer.h> - -struct slow_work; -#ifdef CONFIG_SLOW_WORK_DEBUG -struct seq_file; -#endif - -/* - * The operations used to support slow work items - */ -struct slow_work_ops { - /* owner */ - struct module *owner; - - /* get a ref on a work item - * - return 0 if successful, -ve if not - */ - int (*get_ref)(struct slow_work *work); - - /* discard a ref to a work item */ - void (*put_ref)(struct slow_work *work); - - /* execute a work item */ - void (*execute)(struct slow_work *work); - -#ifdef CONFIG_SLOW_WORK_DEBUG - /* describe a work item for debugfs */ - void (*desc)(struct slow_work *work, struct seq_file *m); -#endif -}; - -/* - * A slow work item - * - A reference is held on the parent object by the thread pool when it is - * queued - */ -struct slow_work { - struct module *owner; /* the owning module */ - unsigned long flags; -#define SLOW_WORK_PENDING 0 /* item pending (further) execution */ -#define SLOW_WORK_EXECUTING 1 /* item currently executing */ -#define SLOW_WORK_ENQ_DEFERRED 2 /* item enqueue deferred */ -#define SLOW_WORK_VERY_SLOW 3 /* item is very slow */ -#define SLOW_WORK_CANCELLING 4 /* item is being cancelled, don't enqueue */ -#define SLOW_WORK_DELAYED 5 /* item is struct delayed_slow_work with active timer */ - const struct slow_work_ops *ops; /* operations table for this item */ - struct list_head link; /* link in queue */ -#ifdef CONFIG_SLOW_WORK_DEBUG - struct timespec mark; /* jiffies at which queued or exec begun */ -#endif -}; - -struct delayed_slow_work { - struct slow_work work; - struct timer_list timer; -}; - -/** - * slow_work_init - Initialise a slow work item - * @work: The work item to initialise - * @ops: The operations to use to handle the slow work item - * - * Initialise a slow work item. - */ -static inline void slow_work_init(struct slow_work *work, - const struct slow_work_ops *ops) -{ - work->flags = 0; - work->ops = ops; - INIT_LIST_HEAD(&work->link); -} - -/** - * slow_work_init - Initialise a delayed slow work item - * @work: The work item to initialise - * @ops: The operations to use to handle the slow work item - * - * Initialise a delayed slow work item. - */ -static inline void delayed_slow_work_init(struct delayed_slow_work *dwork, - const struct slow_work_ops *ops) -{ - init_timer(&dwork->timer); - slow_work_init(&dwork->work, ops); -} - -/** - * vslow_work_init - Initialise a very slow work item - * @work: The work item to initialise - * @ops: The operations to use to handle the slow work item - * - * Initialise a very slow work item. This item will be restricted such that - * only a certain number of the pool threads will be able to execute items of - * this type. - */ -static inline void vslow_work_init(struct slow_work *work, - const struct slow_work_ops *ops) -{ - work->flags = 1 << SLOW_WORK_VERY_SLOW; - work->ops = ops; - INIT_LIST_HEAD(&work->link); -} - -/** - * slow_work_is_queued - Determine if a slow work item is on the work queue - * work: The work item to test - * - * Determine if the specified slow-work item is on the work queue. This - * returns true if it is actually on the queue. - * - * If the item is executing and has been marked for requeue when execution - * finishes, then false will be returned. - * - * Anyone wishing to wait for completion of execution can wait on the - * SLOW_WORK_EXECUTING bit. - */ -static inline bool slow_work_is_queued(struct slow_work *work) -{ - unsigned long flags = work->flags; - return flags & SLOW_WORK_PENDING && !(flags & SLOW_WORK_EXECUTING); -} - -extern int slow_work_enqueue(struct slow_work *work); -extern void slow_work_cancel(struct slow_work *work); -extern int slow_work_register_user(struct module *owner); -extern void slow_work_unregister_user(struct module *owner); - -extern int delayed_slow_work_enqueue(struct delayed_slow_work *dwork, - unsigned long delay); - -static inline void delayed_slow_work_cancel(struct delayed_slow_work *dwork) -{ - slow_work_cancel(&dwork->work); -} - -extern bool slow_work_sleep_till_thread_needed(struct slow_work *work, - signed long *_timeout); - -#ifdef CONFIG_SYSCTL -extern ctl_table slow_work_sysctls[]; -#endif - -#endif /* CONFIG_SLOW_WORK */ -#endif /* _LINUX_SLOW_WORK_H */ diff --git a/init/Kconfig b/init/Kconfig index 5cff9a980c3..cb64c5889e0 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1143,30 +1143,6 @@ config TRACEPOINTS source "arch/Kconfig" -config SLOW_WORK - default n - bool - help - The slow work thread pool provides a number of dynamically allocated - threads that can be used by the kernel to perform operations that - take a relatively long time. - - An example of this would be CacheFiles doing a path lookup followed - by a series of mkdirs and a create call, all of which have to touch - disk. - - See Documentation/slow-work.txt. - -config SLOW_WORK_DEBUG - bool "Slow work debugging through debugfs" - default n - depends on SLOW_WORK && DEBUG_FS - help - Display the contents of the slow work run queue through debugfs, - including items currently executing. - - See Documentation/slow-work.txt. - endmenu # General setup config HAVE_GENERIC_DMA_COHERENT diff --git a/kernel/Makefile b/kernel/Makefile index 057472fbc27..2484ac39b2e 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -99,8 +99,6 @@ obj-$(CONFIG_TRACING) += trace/ obj-$(CONFIG_X86_DS) += trace/ obj-$(CONFIG_RING_BUFFER) += trace/ obj-$(CONFIG_SMP) += sched_cpupri.o -obj-$(CONFIG_SLOW_WORK) += slow-work.o -obj-$(CONFIG_SLOW_WORK_DEBUG) += slow-work-debugfs.o obj-$(CONFIG_PERF_EVENTS) += perf_event.o obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o obj-$(CONFIG_USER_RETURN_NOTIFIER) += user-return-notifier.o diff --git a/kernel/slow-work-debugfs.c b/kernel/slow-work-debugfs.c deleted file mode 100644 index e45c4364529..00000000000 --- a/kernel/slow-work-debugfs.c +++ /dev/null @@ -1,227 +0,0 @@ -/* Slow work debugging - * - * Copyright (C) 2009 Red Hat, Inc. All Rights Reserved. - * Written by David Howells (dhowells@redhat.com) - * - * This program is free software; you can redistribute it and/or - * modify it under the terms of the GNU General Public Licence - * as published by the Free Software Foundation; either version - * 2 of the Licence, or (at your option) any later version. - */ - -#include <linux/module.h> -#include <linux/slow-work.h> -#include <linux/fs.h> -#include <linux/time.h> -#include <linux/seq_file.h> -#include "slow-work.h" - -#define ITERATOR_SHIFT (BITS_PER_LONG - 4) -#define ITERATOR_SELECTOR (0xfUL << ITERATOR_SHIFT) -#define ITERATOR_COUNTER (~ITERATOR_SELECTOR) - -void slow_work_new_thread_desc(struct slow_work *work, struct seq_file *m) -{ - seq_puts(m, "Slow-work: New thread"); -} - -/* - * Render the time mark field on a work item into a 5-char time with units plus - * a space - */ -static void slow_work_print_mark(struct seq_file *m, struct slow_work *work) -{ - struct timespec now, diff; - - now = CURRENT_TIME; - diff = timespec_sub(now, work->mark); - - if (diff.tv_sec < 0) - seq_puts(m, " -ve "); - else if (diff.tv_sec == 0 && diff.tv_nsec < 1000) - seq_printf(m, "%3luns ", diff.tv_nsec); - else if (diff.tv_sec == 0 && diff.tv_nsec < 1000000) - seq_printf(m, "%3luus ", diff.tv_nsec / 1000); - else if (diff.tv_sec == 0 && diff.tv_nsec < 1000000000) - seq_printf(m, "%3lums ", diff.tv_nsec / 1000000); - else if (diff.tv_sec <= 1) - seq_puts(m, " 1s "); - else if (diff.tv_sec < 60) - seq_printf(m, "%4lus ", diff.tv_sec); - else if (diff.tv_sec < 60 * 60) - seq_printf(m, "%4lum ", diff.tv_sec / 60); - else if (diff.tv_sec < 60 * 60 * 24) - seq_printf(m, "%4luh ", diff.tv_sec / 3600); - else - seq_puts(m, "exces "); -} - -/* - * Describe a slow work item for debugfs - */ -static int slow_work_runqueue_show(struct seq_file *m, void *v) -{ - struct slow_work *work; - struct list_head *p = v; - unsigned long id; - - switch ((unsigned long) v) { - case 1: - seq_puts(m, "THR PID ITEM ADDR FL MARK DESC\n"); - return 0; - case 2: - seq_puts(m, "=== ===== ================ == ===== ==========\n"); - return 0; - - case 3 ... 3 + SLOW_WORK_THREAD_LIMIT - 1: - id = (unsigned long) v - 3; - - read_lock(&slow_work_execs_lock); - work = slow_work_execs[id]; - if (work) { - smp_read_barrier_depends(); - - seq_printf(m, "%3lu %5d %16p %2lx ", - id, slow_work_pids[id], work, work->flags); - slow_work_print_mark(m, work); - - if (work->ops->desc) - work->ops->desc(work, m); - seq_putc(m, '\n'); - } - read_unlock(&slow_work_execs_lock); - return 0; - - default: - work = list_entry(p, struct slow_work, link); - seq_printf(m, "%3s - %16p %2lx ", - work->flags & SLOW_WORK_VERY_SLOW ? "vsq" : "sq", - work, work->flags); - slow_work_print_mark(m, work); - - if (work->ops->desc) - work->ops->desc(work, m); - seq_putc(m, '\n'); - return 0; - } -} - -/* - * map the iterator to a work item - */ -static void *slow_work_runqueue_index(struct seq_file *m, loff_t *_pos) -{ - struct list_head *p; - unsigned long count, id; - - switch (*_pos >> ITERATOR_SHIFT) { - case 0x0: - if (*_pos == 0) - *_pos = 1; - if (*_pos < 3) - return (void *)(unsigned long) *_pos; - if (*_pos < 3 + SLOW_WORK_THREAD_LIMIT) - for (id = *_pos - 3; - id < SLOW_WORK_THREAD_LIMIT; - id++, (*_pos)++) - if (slow_work_execs[id]) - return (void *)(unsigned long) *_pos; - *_pos = 0x1UL << ITERATOR_SHIFT; - - case 0x1: - count = *_pos & ITERATOR_COUNTER; - list_for_each(p, &slow_work_queue) { - if (count == 0) - return p; - count--; - } - *_pos = 0x2UL << ITERATOR_SHIFT; - - case 0x2: - count = *_pos & ITERATOR_COUNTER; - list_for_each(p, &vslow_work_queue) { - if (count == 0) - return p; - count--; - } - *_pos = 0x3UL << ITERATOR_SHIFT; - - default: - return NULL; - } -} - -/* - * set up the iterator to start reading from the first line - */ -static void *slow_work_runqueue_start(struct seq_file *m, loff_t *_pos) -{ - spin_lock_irq(&slow_work_queue_lock); - return slow_work_runqueue_index(m, _pos); -} - -/* - * move to the next line - */ -static void *slow_work_runqueue_next(struct seq_file *m, void *v, loff_t *_pos) -{ - struct list_head *p = v; - unsigned long selector = *_pos >> ITERATOR_SHIFT; - - (*_pos)++; - switch (selector) { - case 0x0: - return slow_work_runqueue_index(m, _pos); - - case 0x1: - if (*_pos >> ITERATOR_SHIFT == 0x1) { - p = p->next; - if (p != &slow_work_queue) - return p; - } - *_pos = 0x2UL << ITERATOR_SHIFT; - p = &vslow_work_queue; - - case 0x2: - if (*_pos >> ITERATOR_SHIFT == 0x2) { - p = p->next; - if (p != &vslow_work_queue) - return p; - } - *_pos = 0x3UL << ITERATOR_SHIFT; - - default: - return NULL; - } -} - -/* - * clean up after reading - */ -static void slow_work_runqueue_stop(struct seq_file *m, void *v) -{ - spin_unlock_irq(&slow_work_queue_lock); -} - -static const struct seq_operations slow_work_runqueue_ops = { - .start = slow_work_runqueue_start, - .stop = slow_work_runqueue_stop, - .next = slow_work_runqueue_next, - .show = slow_work_runqueue_show, -}; - -/* - * open "/sys/kernel/debug/slow_work/runqueue" to list queue contents - */ -static int slow_work_runqueue_open(struct inode *inode, struct file *file) -{ - return seq_open(file, &slow_work_runqueue_ops); -} - -const struct file_operations slow_work_runqueue_fops = { - .owner = THIS_MODULE, - .open = slow_work_runqueue_open, - .read = seq_read, - .llseek = seq_lseek, - .release = seq_release, -}; diff --git a/kernel/slow-work.c b/kernel/slow-work.c deleted file mode 100644 index 7d3f4fa9ef4..00000000000 --- a/kernel/slow-work.c +++ /dev/null @@ -1,1068 +0,0 @@ -/* Worker thread pool for slow items, such as filesystem lookups or mkdirs - * - * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved. - * Written by David Howells (dhowells@redhat.com) - * - * This program is free software; you can redistribute it and/or - * modify it under the terms of the GNU General Public Licence - * as published by the Free Software Foundation; either version - * 2 of the Licence, or (at your option) any later version. - * - * See Documentation/slow-work.txt - */ - -#include <linux/module.h> -#include <linux/slow-work.h> -#include <linux/kthread.h> -#include <linux/freezer.h> -#include <linux/wait.h> -#include <linux/debugfs.h> -#include "slow-work.h" - -static void slow_work_cull_timeout(unsigned long); -static void slow_work_oom_timeout(unsigned long); - -#ifdef CONFIG_SYSCTL -static int slow_work_min_threads_sysctl(struct ctl_table *, int, - void __user *, size_t *, loff_t *); - -static int slow_work_max_threads_sysctl(struct ctl_table *, int , - void __user *, size_t *, loff_t *); -#endif - -/* - * The pool of threads has at least min threads in it as long as someone is - * using the facility, and may have as many as max. - * - * A portion of the pool may be processing very slow operations. - */ -static unsigned slow_work_min_threads = 2; -static unsigned slow_work_max_threads = 4; -static unsigned vslow_work_proportion = 50; /* % of threads that may process - * very slow work */ - -#ifdef CONFIG_SYSCTL -static const int slow_work_min_min_threads = 2; -static int slow_work_max_max_threads = SLOW_WORK_THREAD_LIMIT; -static const int slow_work_min_vslow = 1; -static const int slow_work_max_vslow = 99; - -ctl_table slow_work_sysctls[] = { - { - .procname = "min-threads", - .data = &slow_work_min_threads, - .maxlen = sizeof(unsigned), - .mode = 0644, - .proc_handler = slow_work_min_threads_sysctl, - .extra1 = (void *) &slow_work_min_min_threads, - .extra2 = &slow_work_max_threads, - }, - { - .procname = "max-threads", - .data = &slow_work_max_threads, - .maxlen = sizeof(unsigned), - .mode = 0644, - .proc_handler = slow_work_max_threads_sysctl, - .extra1 = &slow_work_min_threads, - .extra2 = (void *) &slow_work_max_max_threads, - }, - { - .procname = "vslow-percentage", - .data = &vslow_work_proportion, - .maxlen = sizeof(unsigned), - .mode = 0644, - .proc_handler = proc_dointvec_minmax, - .extra1 = (void *) &slow_work_min_vslow, - .extra2 = (void *) &slow_work_max_vslow, - }, - {} -}; -#endif - -/* - * The active state of the thread pool - */ -static atomic_t slow_work_thread_count; -static atomic_t vslow_work_executing_count; - -static bool slow_work_may_not_start_new_thread; -static bool slow_work_cull; /* cull a thread due to lack of activity */ -static DEFINE_TIMER(slow_work_cull_timer, slow_work_cull_timeout, 0, 0); -static DEFINE_TIMER(slow_work_oom_timer, slow_work_oom_timeout, 0, 0); -static struct slow_work slow_work_new_thread; /* new thread starter */ - -/* - * slow work ID allocation (use slow_work_queue_lock) - */ -static DECLARE_BITMAP(slow_work_ids, SLOW_WORK_THREAD_LIMIT); - -/* - * Unregistration tracking to prevent put_ref() from disappearing during module - * unload - */ -#ifdef CONFIG_MODULES -static struct module *slow_work_thread_processing[SLOW_WORK_THREAD_LIMIT]; -static struct module *slow_work_unreg_module; -static struct slow_work *slow_work_unreg_work_item; -static DECLARE_WAIT_QUEUE_HEAD(slow_work_unreg_wq); -static DEFINE_MUTEX(slow_work_unreg_sync_lock); - -static void slow_work_set_thread_processing(int id, struct slow_work *work) -{ - if (work) - slow_work_thread_processing[id] = work->owner; -} -static void slow_work_done_thread_processing(int id, struct slow_work *work) -{ - struct module *module = slow_work_thread_processing[id]; - - slow_work_thread_processing[id] = NULL; - smp_mb(); - if (slow_work_unreg_work_item == work || - slow_work_unreg_module == module) - wake_up_all(&slow_work_unreg_wq); -} -static void slow_work_clear_thread_processing(int id) -{ - slow_work_thread_processing[id] = NULL; -} -#else -static void slow_work_set_thread_processing(int id, struct slow_work *work) {} -static void slow_work_done_thread_processing(int id, struct slow_work *work) {} -static void slow_work_clear_thread_processing(int id) {} -#endif - -/* - * Data for tracking currently executing items for indication through /proc - */ -#ifdef CONFIG_SLOW_WORK_DEBUG -struct slow_work *slow_work_execs[SLOW_WORK_THREAD_LIMIT]; -pid_t slow_work_pids[SLOW_WORK_THREAD_LIMIT]; -DEFINE_RWLOCK(slow_work_execs_lock); -#endif - -/* - * The queues of work items and the lock governing access to them. These are - * shared between all the CPUs. It doesn't make sense to have per-CPU queues - * as the number of threads bears no relation to the number of CPUs. - * - * There are two queues of work items: one for slow work items, and one for - * very slow work items. - */ -LIST_HEAD(slow_work_queue); -LIST_HEAD(vslow_work_queue); -DEFINE_SPINLOCK(slow_work_queue_lock); - -/* - * The following are two wait queues that get pinged when a work item is placed - * on an empty queue. These allow work items that are hogging a thread by - * sleeping in a way that could be deferred to yield their thread and enqueue - * themselves. - */ -static DECLARE_WAIT_QUEUE_HEAD(slow_work_queue_waits_for_occupation); -static DECLARE_WAIT_QUEUE_HEAD(vslow_work_queue_waits_for_occupation); - -/* - * The thread controls. A variable used to signal to the threads that they - * should exit when the queue is empty, a waitqueue used by the threads to wait - * for signals, and a completion set by the last thread to exit. - */ -static bool slow_work_threads_should_exit; -static DECLARE_WAIT_QUEUE_HEAD(slow_work_thread_wq); -static DECLARE_COMPLETION(slow_work_last_thread_exited); - -/* - * The number of users of the thread pool and its lock. Whilst this is zero we - * have no threads hanging around, and when this reaches zero, we wait for all - * active or queued work items to complete and kill all the threads we do have. - */ -static int slow_work_user_count; -static DEFINE_MUTEX(slow_work_user_lock); - -static inline int slow_work_get_ref(struct slow_work *work) -{ - if (work->ops->get_ref) - return work->ops->get_ref(work); - - return 0; -} - -static inline void slow_work_put_ref(struct slow_work *work) -{ - if (work->ops->put_ref) - work->ops->put_ref(work); -} - -/* - * Calculate the maximum number of active threads in the pool that are - * permitted to process very slow work items. - * - * The answer is rounded up to at least 1, but may not equal or exceed the - * maximum number of the threads in the pool. This means we always have at - * least one thread that can process slow work items, and we always have at - * least one thread that won't get tied up doing so. - */ -static unsigned slow_work_calc_vsmax(void) -{ - unsigned vsmax; - - vsmax = atomic_read(&slow_work_thread_count) * vslow_work_proportion; - vsmax /= 100; - vsmax = max(vsmax, 1U); - return min(vsmax, slow_work_max_threads - 1); -} - -/* - * Attempt to execute stuff queued on a slow thread. Return true if we managed - * it, false if there was nothing to do. - */ -static noinline bool slow_work_execute(int id) -{ - struct slow_work *work = NULL; - unsigned vsmax; - bool very_slow; - - vsmax = slow_work_calc_vsmax(); - - /* see if we can schedule a new thread to be started if we're not - * keeping up with the work */ - if (!waitqueue_active(&slow_work_thread_wq) && - (!list_empty(&slow_work_queue) || !list_empty(&vslow_work_queue)) && - atomic_read(&slow_work_thread_count) < slow_work_max_threads && - !slow_work_may_not_start_new_thread) - slow_work_enqueue(&slow_work_new_thread); - - /* find something to execute */ - spin_lock_irq(&slow_work_queue_lock); - if (!list_empty(&vslow_work_queue) && - atomic_read(&vslow_work_executing_count) < vsmax) { - work = list_entry(vslow_work_queue.next, - struct slow_work, link); - if (test_and_set_bit_lock(SLOW_WORK_EXECUTING, &work->flags)) - BUG(); - list_del_init(&work->link); - atomic_inc(&vslow_work_executing_count); - very_slow = true; - } else if (!list_empty(&slow_work_queue)) { - work = list_entry(slow_work_queue.next, - struct slow_work, link); - if (test_and_set_bit_lock(SLOW_WORK_EXECUTING, &work->flags)) - BUG(); - list_del_init(&work->link); - very_slow = false; - } else { - very_slow = false; /* avoid the compiler warning */ - } - - slow_work_set_thread_processing(id, work); - if (work) { - slow_work_mark_time(work); - slow_work_begin_exec(id, work); - } - - spin_unlock_irq(&slow_work_queue_lock); - - if (!work) - return false; - - if (!test_and_clear_bit(SLOW_WORK_PENDING, &work->flags)) - BUG(); - - /* don't execute if the work is in the process of being cancelled */ - if (!test_bit(SLOW_WORK_CANCELLING, &work->flags)) |