*
* Copyright (C) 2002, Linus Torvalds.
*
- * 09Apr2002 akpm@zip.com.au
+ * 09Apr2002 Andrew Morton
* Initial version
* 29Feb2004 kaos@sgi.com
* Move worker thread creation to kthread to avoid chewing
#include <linux/gfp.h>
#include <linux/init.h>
#include <linux/module.h>
-#include <linux/fs.h> // Needed by writeback.h
-#include <linux/writeback.h> // Prototypes pdflush_operation()
+#include <linux/fs.h> /* Needed by writeback.h */
+#include <linux/writeback.h> /* Prototypes pdflush_operation() */
#include <linux/kthread.h>
#include <linux/cpuset.h>
+#include <linux/freezer.h>
/*
int nr_pdflush_threads = 0;
/*
+ * The max/min number of pdflush threads. R/W by sysctl at
+ * /proc/sys/vm/nr_pdflush_threads_max/min
+ */
+int nr_pdflush_threads_max __read_mostly = MAX_PDFLUSH_THREADS;
+int nr_pdflush_threads_min __read_mostly = MIN_PDFLUSH_THREADS;
+
+
+/*
* The time at which the pdflush thread pool last went empty
*/
static unsigned long last_empty_jifs;
* Thread pool management algorithm:
*
* - The minimum and maximum number of pdflush instances are bound
- * by MIN_PDFLUSH_THREADS and MAX_PDFLUSH_THREADS.
+ * by nr_pdflush_threads_min and nr_pdflush_threads_max.
*
* - If there have been no idle pdflush instances for 1 second, create
* a new one.
static int __pdflush(struct pdflush_work *my_work)
{
current->flags |= PF_FLUSHER | PF_SWAPWRITE;
+ set_freezable();
my_work->fn = NULL;
my_work->who = current;
INIT_LIST_HEAD(&my_work->list);
spin_lock_irq(&pdflush_lock);
- nr_pdflush_threads++;
for ( ; ; ) {
struct pdflush_work *pdf;
list_move(&my_work->list, &pdflush_list);
my_work->when_i_went_to_sleep = jiffies;
spin_unlock_irq(&pdflush_lock);
-
schedule();
- if (try_to_freeze()) {
- spin_lock_irq(&pdflush_lock);
- continue;
- }
-
+ try_to_freeze();
spin_lock_irq(&pdflush_lock);
if (!list_empty(&my_work->list)) {
- printk("pdflush: bogus wakeup!\n");
+ /*
+ * Someone woke us up, but without removing our control
+ * structure from the global list. swsusp will do this
+ * in try_to_freeze()->refrigerator(). Handle it.
+ */
my_work->fn = NULL;
continue;
}
if (my_work->fn == NULL) {
- printk("pdflush: NULL work function\n");
+ printk("pdflush: bogus wakeup\n");
continue;
}
spin_unlock_irq(&pdflush_lock);
(*my_work->fn)(my_work->arg0);
+ spin_lock_irq(&pdflush_lock);
+
/*
* Thread creation: For how long have there been zero
* available threads?
+ *
+ * To throttle creation, we reset last_empty_jifs.
*/
- if (jiffies - last_empty_jifs > 1 * HZ) {
- /* unlocked list_empty() test is OK here */
- if (list_empty(&pdflush_list)) {
- /* unlocked test is OK here */
- if (nr_pdflush_threads < MAX_PDFLUSH_THREADS)
- start_one_pdflush_thread();
+ if (time_after(jiffies, last_empty_jifs + 1 * HZ)) {
+ if (list_empty(&pdflush_list) &&
+ nr_pdflush_threads < nr_pdflush_threads_max) {
+ last_empty_jifs = jiffies;
+ nr_pdflush_threads++;
+ spin_unlock_irq(&pdflush_lock);
+ start_one_pdflush_thread();
+ spin_lock_irq(&pdflush_lock);
}
}
- spin_lock_irq(&pdflush_lock);
my_work->fn = NULL;
/*
*/
if (list_empty(&pdflush_list))
continue;
- if (nr_pdflush_threads <= MIN_PDFLUSH_THREADS)
+ if (nr_pdflush_threads <= nr_pdflush_threads_min)
continue;
pdf = list_entry(pdflush_list.prev, struct pdflush_work, list);
- if (jiffies - pdf->when_i_went_to_sleep > 1 * HZ) {
+ if (time_after(jiffies, pdf->when_i_went_to_sleep + 1 * HZ)) {
/* Limit exit rate */
pdf->when_i_went_to_sleep = jiffies;
break; /* exeunt */
static int pdflush(void *dummy)
{
struct pdflush_work my_work;
- cpumask_t cpus_allowed;
+ cpumask_var_t cpus_allowed;
+
+ /*
+ * Since the caller doesn't even check kthread_run() worked, let's not
+ * freak out too much if this fails.
+ */
+ if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
+ printk(KERN_WARNING "pdflush failed to allocate cpumask\n");
+ return 0;
+ }
/*
* pdflush can spend a lot of time doing encryption via dm-crypt. We
/*
* Some configs put our parent kthread in a limited cpuset,
- * which kthread() overrides, forcing cpus_allowed == CPU_MASK_ALL.
+ * which kthread() overrides, forcing cpus_allowed == cpu_all_mask.
* Our needs are more modest - cut back to our cpusets cpus_allowed.
* This is needed as pdflush's are dynamically created and destroyed.
* The boottime pdflush's are easily placed w/o these 2 lines.
*/
- cpus_allowed = cpuset_cpus_allowed(current);
- set_cpus_allowed(current, cpus_allowed);
+ cpuset_cpus_allowed(current, cpus_allowed);
+ set_cpus_allowed_ptr(current, cpus_allowed);
+ free_cpumask_var(cpus_allowed);
return __pdflush(&my_work);
}
unsigned long flags;
int ret = 0;
- if (fn == NULL)
- BUG(); /* Hard to diagnose if it's deferred */
+ BUG_ON(fn == NULL); /* Hard to diagnose if it's deferred */
spin_lock_irqsave(&pdflush_lock, flags);
if (list_empty(&pdflush_list)) {
- spin_unlock_irqrestore(&pdflush_lock, flags);
ret = -1;
} else {
struct pdflush_work *pdf;
pdf->fn = fn;
pdf->arg0 = arg0;
wake_up_process(pdf->who);
- spin_unlock_irqrestore(&pdflush_lock, flags);
}
+ spin_unlock_irqrestore(&pdflush_lock, flags);
+
return ret;
}
static void start_one_pdflush_thread(void)
{
- kthread_run(pdflush, NULL, "pdflush");
+ struct task_struct *k;
+
+ k = kthread_run(pdflush, NULL, "pdflush");
+ if (unlikely(IS_ERR(k))) {
+ spin_lock_irq(&pdflush_lock);
+ nr_pdflush_threads--;
+ spin_unlock_irq(&pdflush_lock);
+ }
}
static int __init pdflush_init(void)
{
int i;
- for (i = 0; i < MIN_PDFLUSH_THREADS; i++)
+ /*
+ * Pre-set nr_pdflush_threads... If we fail to create,
+ * the count will be decremented.
+ */
+ nr_pdflush_threads = nr_pdflush_threads_min;
+
+ for (i = 0; i < nr_pdflush_threads_min; i++)
start_one_pdflush_thread();
return 0;
}
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff