mirror_zfs/include/os/linux/spl/sys/taskq.h
Rich Ercolani 35a6247c5f
Add a delay to tearing down threads.
It's been observed that in certain workloads (zvol-related being a
big one), ZFS will end up spending a large amount of time spinning
up taskqs only to tear them down again almost immediately, then
spin them up again...

I noticed this when I looked at what my mostly-idle system was doing
and wondered how on earth taskq creation/destroy was a bunch of time...

So I added a configurable delay to avoid it tearing down tasks the
first time it notices them idle, and the total number of threads at
steady state went up, but the amount of time being burned just
tearing down/turning up new ones almost vanished.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rich Ercolani <rincebrain@gmail.com>
Closes #14938
2023-06-26 13:57:12 -07:00

171 lines
5.7 KiB
C

/*
* Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
* Copyright (C) 2007 The Regents of the University of California.
* Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
* Written by Brian Behlendorf <behlendorf1@llnl.gov>.
* UCRL-CODE-235197
*
* This file is part of the SPL, Solaris Porting Layer.
*
* The SPL is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*
* The SPL is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*
* You should have received a copy of the GNU General Public License along
* with the SPL. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef _SPL_TASKQ_H
#define _SPL_TASKQ_H
#include <linux/module.h>
#include <linux/gfp.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/kthread.h>
#include <sys/types.h>
#include <sys/thread.h>
#include <sys/rwlock.h>
#include <sys/wait.h>
#define TASKQ_NAMELEN 31
#define TASKQ_PREPOPULATE 0x00000001
#define TASKQ_CPR_SAFE 0x00000002
#define TASKQ_DYNAMIC 0x00000004
#define TASKQ_THREADS_CPU_PCT 0x00000008
#define TASKQ_DC_BATCH 0x00000010
#define TASKQ_ACTIVE 0x80000000
/*
* Flags for taskq_dispatch. TQ_SLEEP/TQ_NOSLEEP should be same as
* KM_SLEEP/KM_NOSLEEP. TQ_NOQUEUE/TQ_NOALLOC are set particularly
* large so as not to conflict with already used GFP_* defines.
*/
#define TQ_SLEEP 0x00000000
#define TQ_NOSLEEP 0x00000001
#define TQ_PUSHPAGE 0x00000002
#define TQ_NOQUEUE 0x01000000
#define TQ_NOALLOC 0x02000000
#define TQ_NEW 0x04000000
#define TQ_FRONT 0x08000000
/*
* Reserved taskqid values.
*/
#define TASKQID_INVALID ((taskqid_t)0)
#define TASKQID_INITIAL ((taskqid_t)1)
/*
* spin_lock(lock) and spin_lock_nested(lock,0) are equivalent,
* so TQ_LOCK_DYNAMIC must not evaluate to 0
*/
typedef enum tq_lock_role {
TQ_LOCK_GENERAL = 0,
TQ_LOCK_DYNAMIC = 1,
} tq_lock_role_t;
typedef unsigned long taskqid_t;
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 */
/* If PERCPU flag is set, percent of NCPUs to have as threads */
int tq_cpu_pct;
int tq_pri; /* priority */
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 taskq_ent_t's */
struct list_head tq_pend_list; /* pending taskq_ent_t's */
struct list_head tq_prio_list; /* priority taskq_ent_t's */
struct list_head tq_delay_list; /* delayed taskq_ent_t's */
struct list_head tq_taskqs; /* all taskq_t's */
spl_wait_queue_head_t tq_work_waitq; /* new work waitq */
spl_wait_queue_head_t tq_wait_waitq; /* wait waitq */
tq_lock_role_t tq_lock_class; /* class when taking tq_lock */
/* list node for the cpu hotplug callback */
struct hlist_node tq_hp_cb_node;
boolean_t tq_hp_support;
unsigned long lastshouldstop; /* when to purge dynamic */
} taskq_t;
typedef struct taskq_ent {
spinlock_t tqent_lock;
spl_wait_queue_head_t tqent_waitq;
struct timer_list tqent_timer;
struct list_head tqent_list;
taskqid_t tqent_id;
task_func_t *tqent_func;
void *tqent_arg;
taskq_t *tqent_taskq;
uintptr_t tqent_flags;
unsigned long tqent_birth;
} taskq_ent_t;
#define TQENT_FLAG_PREALLOC 0x1
#define TQENT_FLAG_CANCEL 0x2
typedef struct taskq_thread {
struct list_head tqt_thread_list;
struct list_head tqt_active_list;
struct task_struct *tqt_thread;
taskq_t *tqt_tq;
taskqid_t tqt_id;
taskq_ent_t *tqt_task;
uintptr_t tqt_flags;
} taskq_thread_t;
/* Global system-wide dynamic task queue available for all consumers */
extern taskq_t *system_taskq;
/* Global dynamic task queue for long delay */
extern taskq_t *system_delay_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);
extern void taskq_dispatch_ent(taskq_t *, task_func_t, void *, uint_t,
taskq_ent_t *);
extern int taskq_empty_ent(taskq_ent_t *);
extern void taskq_init_ent(taskq_ent_t *);
extern taskq_t *taskq_create(const char *, int, pri_t, int, int, uint_t);
extern void taskq_destroy(taskq_t *);
extern void taskq_wait_id(taskq_t *, taskqid_t);
extern void taskq_wait_outstanding(taskq_t *, taskqid_t);
extern void taskq_wait(taskq_t *);
extern int taskq_cancel_id(taskq_t *, taskqid_t);
extern int taskq_member(taskq_t *, kthread_t *);
extern taskq_t *taskq_of_curthread(void);
#define taskq_create_proc(name, nthreads, pri, min, max, proc, flags) \
taskq_create(name, nthreads, pri, min, max, flags)
#define taskq_create_sysdc(name, nthreads, min, max, proc, dc, flags) \
((void) sizeof (dc), \
taskq_create(name, nthreads, maxclsyspri, min, max, flags))
int spl_taskq_init(void);
void spl_taskq_fini(void);
#endif /* _SPL_TASKQ_H */