* 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/kthread.h>
#include <linux/freezer.h>
#include <linux/wait.h>
-#include <asm/system.h>
#define SLOW_WORK_CULL_TIMEOUT (5 * HZ) /* cull threads 5s after running out of
* things to do */
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, struct file *,
+ void __user *, size_t *, loff_t *);
+
+static int slow_work_max_threads_sysctl(struct ctl_table *, int , struct file *,
+ 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.
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 = 255;
+static const int slow_work_min_vslow = 1;
+static const int slow_work_max_vslow = 99;
+
+ctl_table slow_work_sysctls[] = {
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .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,
+ },
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .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,
+ },
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .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,
+ },
+ { .ctl_name = 0 }
+};
+#endif
+
+/*
+ * The active state of the thread pool
+ */
static atomic_t slow_work_thread_count;
static atomic_t vslow_work_executing_count;
EXPORT_SYMBOL(slow_work_enqueue);
/*
+ * Schedule a cull of the thread pool at some time in the near future
+ */
+static void slow_work_schedule_cull(void)
+{
+ mod_timer(&slow_work_cull_timer,
+ round_jiffies(jiffies + SLOW_WORK_CULL_TIMEOUT));
+}
+
+/*
* Worker thread culling algorithm
*/
static bool slow_work_cull_thread(void)
list_empty(&vslow_work_queue) &&
atomic_read(&slow_work_thread_count) >
slow_work_min_threads) {
- mod_timer(&slow_work_cull_timer,
- jiffies + SLOW_WORK_CULL_TIMEOUT);
+ slow_work_schedule_cull();
do_cull = true;
}
}
vsmax *= atomic_read(&slow_work_thread_count);
vsmax /= 100;
- prepare_to_wait(&slow_work_thread_wq, &wait,
- TASK_INTERRUPTIBLE);
+ prepare_to_wait_exclusive(&slow_work_thread_wq, &wait,
+ TASK_INTERRUPTIBLE);
if (!freezing(current) &&
!slow_work_threads_should_exit &&
!slow_work_available(vsmax) &&
list_empty(&vslow_work_queue) &&
atomic_read(&slow_work_thread_count) >
slow_work_min_threads)
- mod_timer(&slow_work_cull_timer,
- jiffies + SLOW_WORK_CULL_TIMEOUT);
+ slow_work_schedule_cull();
continue;
}
if (atomic_dec_and_test(&slow_work_thread_count))
BUG(); /* we're running on a slow work thread... */
mod_timer(&slow_work_oom_timer,
- jiffies + SLOW_WORK_OOM_TIMEOUT);
+ round_jiffies(jiffies + SLOW_WORK_OOM_TIMEOUT));
} else {
/* ratelimit the starting of new threads */
mod_timer(&slow_work_oom_timer, jiffies + 1);
slow_work_may_not_start_new_thread = false;
}
+#ifdef CONFIG_SYSCTL
+/*
+ * Handle adjustment of the minimum number of threads
+ */
+static int slow_work_min_threads_sysctl(struct ctl_table *table, int write,
+ struct file *filp, void __user *buffer,
+ size_t *lenp, loff_t *ppos)
+{
+ int ret = proc_dointvec_minmax(table, write, filp, buffer, lenp, ppos);
+ int n;
+
+ if (ret == 0) {
+ mutex_lock(&slow_work_user_lock);
+ if (slow_work_user_count > 0) {
+ /* see if we need to start or stop threads */
+ n = atomic_read(&slow_work_thread_count) -
+ slow_work_min_threads;
+
+ if (n < 0 && !slow_work_may_not_start_new_thread)
+ slow_work_enqueue(&slow_work_new_thread);
+ else if (n > 0)
+ slow_work_schedule_cull();
+ }
+ mutex_unlock(&slow_work_user_lock);
+ }
+
+ return ret;
+}
+
+/*
+ * Handle adjustment of the maximum number of threads
+ */
+static int slow_work_max_threads_sysctl(struct ctl_table *table, int write,
+ struct file *filp, void __user *buffer,
+ size_t *lenp, loff_t *ppos)
+{
+ int ret = proc_dointvec_minmax(table, write, filp, buffer, lenp, ppos);
+ int n;
+
+ if (ret == 0) {
+ mutex_lock(&slow_work_user_lock);
+ if (slow_work_user_count > 0) {
+ /* see if we need to stop threads */
+ n = slow_work_max_threads -
+ atomic_read(&slow_work_thread_count);
+
+ if (n < 0)
+ slow_work_schedule_cull();
+ }
+ mutex_unlock(&slow_work_user_lock);
+ }
+
+ return ret;
+}
+#endif /* CONFIG_SYSCTL */
+
/**
* slow_work_register_user - Register a user of the facility
*
if (slow_work_user_count == 0) {
printk(KERN_NOTICE "Slow work thread pool: Shutting down\n");
slow_work_threads_should_exit = true;
+ del_timer_sync(&slow_work_cull_timer);
+ del_timer_sync(&slow_work_oom_timer);
wake_up_all(&slow_work_thread_wq);
wait_for_completion(&slow_work_last_thread_exited);
printk(KERN_NOTICE "Slow work thread pool:"
" Shut down complete\n");
}
- del_timer_sync(&slow_work_cull_timer);
-
mutex_unlock(&slow_work_user_lock);
}
EXPORT_SYMBOL(slow_work_unregister_user);
{
unsigned nr_cpus = num_possible_cpus();
- if (nr_cpus > slow_work_max_threads)
+ if (slow_work_max_threads < nr_cpus)
slow_work_max_threads = nr_cpus;
+#ifdef CONFIG_SYSCTL
+ if (slow_work_max_max_threads < nr_cpus * 2)
+ slow_work_max_max_threads = nr_cpus * 2;
+#endif
return 0;
}
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