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Provide kstat for taskqs
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This patch provides 2 new kstats to display task queues:

  /proc/spl/taskqs-all - Display all task queues
  /proc/spl/taskqs - Display only "active" task queues

A task queue is considered to be "active" if it currently has active
(running) threads or if any of its pending, priority, delay or waitq
lists are not empty.

If the task queue has running threads, displays each thread function's
address (symbolically, if possibly) and its argument.

If the task queue has a non-empty list of pending, priority or delayed
task queue entries (taskq_ent_t), displays each entry's thread function
address and arguemnt.

If the task queue has any waiters, displays each waiting task's pid.

Note: This patch also updates some comments in taskq.h which referred to
"taskq_t" when they should have referred to "taskq_ent_t".

Signed-off-by: Tim Chase <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Closes openzfs#491
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@dweeezil @behlendorf
dweeezil authored and behlendorf committed Dec 16, 2015
1 parent e0ed96f commit 200366f
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Showing 3 changed files with 283 additions and 7 deletions.
21 changes: 14 additions & 7 deletions include/sys/taskq.h
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Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,7 @@
#include <linux/kthread.h>
#include <sys/types.h>
#include <sys/thread.h>
#include <sys/rwlock.h>

#define TASKQ_NAMELEN 31

Expand Down Expand Up @@ -70,23 +71,25 @@ typedef void (task_func_t)(void *);
typedef struct taskq {
spinlock_t tq_lock; /* protects taskq_t */
char *tq_name; /* taskq name */
int tq_instance; /* instance of tq_name */
struct list_head tq_thread_list; /* list of all threads */
struct list_head tq_active_list; /* list of active threads */
int tq_nactive; /* # of active threads */
int tq_nthreads; /* # of existing threads */
int tq_nspawn; /* # of threads being spawned */
int tq_maxthreads; /* # of threads maximum */
int tq_pri; /* priority */
int tq_minalloc; /* min task_t pool size */
int tq_maxalloc; /* max task_t pool size */
int tq_nalloc; /* cur task_t pool size */
int tq_minalloc; /* min taskq_ent_t pool size */
int tq_maxalloc; /* max taskq_ent_t pool size */
int tq_nalloc; /* cur taskq_ent_t pool size */
uint_t tq_flags; /* flags */
taskqid_t tq_next_id; /* next pend/work id */
taskqid_t tq_lowest_id; /* lowest pend/work id */
struct list_head tq_free_list; /* free task_t's */
struct list_head tq_pend_list; /* pending task_t's */
struct list_head tq_prio_list; /* priority pending task_t's */
struct list_head tq_delay_list; /* delayed task_t's */
struct list_head tq_free_list; /* free taskq_ent_t's */
struct list_head tq_pend_list; /* pending taskq_ent_t's */
struct list_head tq_prio_list; /* priority pending taskq_ent_t's */
struct list_head tq_delay_list; /* delayed taskq_ent_t's */
struct list_head tq_taskqs; /* all taskq_t's */
wait_queue_head_t tq_work_waitq; /* new work waitq */
wait_queue_head_t tq_wait_waitq; /* wait waitq */
tq_lock_role_t tq_lock_class; /* class when taking tq_lock */
Expand Down Expand Up @@ -120,6 +123,10 @@ typedef struct taskq_thread {
/* Global system-wide dynamic task queue available for all consumers */
extern taskq_t *system_taskq;

/* List of all taskqs */
extern struct list_head tq_list;
extern struct rw_semaphore tq_list_sem;

extern taskqid_t taskq_dispatch(taskq_t *, task_func_t, void *, uint_t);
extern taskqid_t taskq_dispatch_delay(taskq_t *, task_func_t, void *,
uint_t, clock_t);
Expand Down
237 changes: 237 additions & 0 deletions module/spl/spl-proc.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,7 @@
#include <sys/kmem.h>
#include <sys/kmem_cache.h>
#include <sys/vmem.h>
#include <sys/taskq.h>
#include <linux/ctype.h>
#include <linux/kmod.h>
#include <linux/seq_file.h>
Expand All @@ -49,6 +50,8 @@ static struct ctl_table_header *spl_header = NULL;
static struct proc_dir_entry *proc_spl = NULL;
static struct proc_dir_entry *proc_spl_kmem = NULL;
static struct proc_dir_entry *proc_spl_kmem_slab = NULL;
static struct proc_dir_entry *proc_spl_taskq_all = NULL;
static struct proc_dir_entry *proc_spl_taskq = NULL;
struct proc_dir_entry *proc_spl_kstat = NULL;

static int
Expand Down Expand Up @@ -215,6 +218,176 @@ proc_dohostid(struct ctl_table *table, int write,
return (rc);
}

static void
taskq_seq_show_headers(struct seq_file *f)
{
seq_printf(f, "%-25s %5s %5s %5s %5s %5s %5s %12s %5s %10s\n",
"taskq", "act", "nthr", "spwn", "maxt", "pri",
"mina", "maxa", "cura", "flags");
}

/* indices into the lheads array below */
#define LHEAD_PEND 0
#define LHEAD_PRIO 1
#define LHEAD_DELAY 2
#define LHEAD_WAIT 3
#define LHEAD_ACTIVE 4
#define LHEAD_SIZE 5

static int
taskq_seq_show_impl(struct seq_file *f, void *p, boolean_t allflag)
{
taskq_t *tq = p;
taskq_thread_t *tqt;
wait_queue_t *wq;
struct task_struct *tsk;
taskq_ent_t *tqe;
char name[100];
struct list_head *lheads[LHEAD_SIZE], *lh;
static char *list_names[LHEAD_SIZE] =
{"pend", "prio", "delay", "wait", "active" };
int i, j, have_lheads = 0;
unsigned long wflags, flags;

spin_lock_irqsave_nested(&tq->tq_lock, flags, tq->tq_lock_class);
spin_lock_irqsave(&tq->tq_wait_waitq.lock, wflags);

/* get the various lists and check whether they're empty */
lheads[LHEAD_PEND] = &tq->tq_pend_list;
lheads[LHEAD_PRIO] = &tq->tq_prio_list;
lheads[LHEAD_DELAY] = &tq->tq_delay_list;
lheads[LHEAD_WAIT] = &tq->tq_wait_waitq.task_list;
lheads[LHEAD_ACTIVE] = &tq->tq_active_list;

for (i = 0; i < LHEAD_SIZE; ++i) {
if (list_empty(lheads[i]))
lheads[i] = NULL;
else
++have_lheads;
}

/* early return in non-"all" mode if lists are all empty */
if (!allflag && !have_lheads) {
spin_unlock_irqrestore(&tq->tq_wait_waitq.lock, wflags);
spin_unlock_irqrestore(&tq->tq_lock, flags);
return (0);
}

/* unlock the waitq quickly */
if (!lheads[LHEAD_WAIT])
spin_unlock_irqrestore(&tq->tq_wait_waitq.lock, wflags);

/* show the base taskq contents */
snprintf(name, sizeof(name), "%s/%d", tq->tq_name, tq->tq_instance);
seq_printf(f, "%-25s ", name);
seq_printf(f, "%5d %5d %5d %5d %5d %5d %12d %5d %10x\n",
tq->tq_nactive, tq->tq_nthreads, tq->tq_nspawn,
tq->tq_maxthreads, tq->tq_pri, tq->tq_minalloc, tq->tq_maxalloc,
tq->tq_nalloc, tq->tq_flags);

/* show the active list */
if (lheads[LHEAD_ACTIVE]) {
j = 0;
list_for_each_entry(tqt, &tq->tq_active_list, tqt_active_list) {
if (j == 0)
seq_printf(f, "\t%s:", list_names[LHEAD_ACTIVE]);
else if (j == 2) {
seq_printf(f, "\n\t ");
j = 0;
}
seq_printf(f, " [%d]%pf(%ps)",
tqt->tqt_thread->pid,
tqt->tqt_task->tqent_func,
tqt->tqt_task->tqent_arg);
++j;
}
seq_printf(f, "\n");
}

for (i = LHEAD_PEND; i <= LHEAD_WAIT; ++i)
if (lheads[i]) {
j = 0;
list_for_each(lh, lheads[i]) {
/* show the wait waitq list */
if (i == LHEAD_WAIT) {
wq = list_entry(lh, wait_queue_t, task_list);
if (j == 0)
seq_printf(f, "\t%s:",
list_names[i]);
else if (j == 12) {
seq_printf(f, "\n\t ");
j = 0;
}
tsk = wq->private;
seq_printf(f, " %d", tsk->pid);
/* pend, prio and delay lists */
} else {
tqe = list_entry(lh, taskq_ent_t,
tqent_list);
if (j == 0)
seq_printf(f, "\t%s:",
list_names[i]);
else if (j == 2) {
seq_printf(f, "\n\t ");
j = 0;
}
seq_printf(f, " %pf(%ps)",
tqe->tqent_func,
tqe->tqent_arg);
}
++j;
}
seq_printf(f, "\n");
}
if (lheads[LHEAD_WAIT])
spin_unlock_irqrestore(&tq->tq_wait_waitq.lock, wflags);
spin_unlock_irqrestore(&tq->tq_lock, flags);

return (0);
}

static int
taskq_all_seq_show(struct seq_file *f, void *p)
{
return (taskq_seq_show_impl(f, p, B_TRUE));
}

static int
taskq_seq_show(struct seq_file *f, void *p)
{
return (taskq_seq_show_impl(f, p, B_FALSE));
}

static void *
taskq_seq_start(struct seq_file *f, loff_t *pos)
{
struct list_head *p;
loff_t n = *pos;

down_read(&tq_list_sem);
if (!n)
taskq_seq_show_headers(f);

p = tq_list.next;
while (n--) {
p = p->next;
if (p == &tq_list)
return (NULL);
}

return (list_entry(p, taskq_t, tq_taskqs));
}

static void *
taskq_seq_next(struct seq_file *f, void *p, loff_t *pos)
{
taskq_t *tq = p;

++*pos;
return ((tq->tq_taskqs.next == &tq_list) ?
NULL : list_entry(tq->tq_taskqs.next, taskq_t, tq_taskqs));
}

static void
slab_seq_show_headers(struct seq_file *f)
{
Expand Down Expand Up @@ -325,6 +498,52 @@ static struct file_operations proc_slab_operations = {
.release = seq_release,
};

static void
taskq_seq_stop(struct seq_file *f, void *v)
{
up_read(&tq_list_sem);
}

static struct seq_operations taskq_all_seq_ops = {
.show = taskq_all_seq_show,
.start = taskq_seq_start,
.next = taskq_seq_next,
.stop = taskq_seq_stop,
};

static struct seq_operations taskq_seq_ops = {
.show = taskq_seq_show,
.start = taskq_seq_start,
.next = taskq_seq_next,
.stop = taskq_seq_stop,
};

static int
proc_taskq_all_open(struct inode *inode, struct file *filp)
{
return seq_open(filp, &taskq_all_seq_ops);
}

static int
proc_taskq_open(struct inode *inode, struct file *filp)
{
return seq_open(filp, &taskq_seq_ops);
}

static struct file_operations proc_taskq_all_operations = {
.open = proc_taskq_all_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};

static struct file_operations proc_taskq_operations = {
.open = proc_taskq_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};

static struct ctl_table spl_kmem_table[] = {
#ifdef DEBUG_KMEM
{
Expand Down Expand Up @@ -476,6 +695,20 @@ spl_proc_init(void)
goto out;
}

proc_spl_taskq_all = proc_create_data("taskq-all", 0444,
proc_spl, &proc_taskq_all_operations, NULL);
if (proc_spl_taskq_all == NULL) {
rc = -EUNATCH;
goto out;
}

proc_spl_taskq = proc_create_data("taskq", 0444,
proc_spl, &proc_taskq_operations, NULL);
if (proc_spl_taskq == NULL) {
rc = -EUNATCH;
goto out;
}

proc_spl_kmem = proc_mkdir("kmem", proc_spl);
if (proc_spl_kmem == NULL) {
rc = -EUNATCH;
Expand All @@ -499,6 +732,8 @@ spl_proc_init(void)
remove_proc_entry("kstat", proc_spl);
remove_proc_entry("slab", proc_spl_kmem);
remove_proc_entry("kmem", proc_spl);
remove_proc_entry("taskq-all", proc_spl);
remove_proc_entry("taskq", proc_spl);
remove_proc_entry("spl", NULL);
unregister_sysctl_table(spl_header);
}
Expand All @@ -512,6 +747,8 @@ spl_proc_fini(void)
remove_proc_entry("kstat", proc_spl);
remove_proc_entry("slab", proc_spl_kmem);
remove_proc_entry("kmem", proc_spl);
remove_proc_entry("taskq-all", proc_spl);
remove_proc_entry("taskq", proc_spl);
remove_proc_entry("spl", NULL);

ASSERT(spl_header != NULL);
Expand Down
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