From c78f2216a947e712fff07f6e79f743d9009e60c8 Mon Sep 17 00:00:00 2001 From: Pierre Habouzit Date: Fri, 16 Dec 2011 16:24:24 +0100 Subject: [PATCH] Pthread Workqueue Regulator (pwqr) initial commit. This contains an alpha/beta quality kernel proof-of-concept driver, plus some code concepts to wrap the syscall in lib/libpwqr.c Signed-off-by: Pierre Habouzit --- .gitignore | 8 + Makefile | 5 + kernel/Makefile | 14 ++ kernel/pwqr.c | 648 ++++++++++++++++++++++++++++++++++++++++++++++++ kernel/pwqr.h | 42 ++++ lib/COPYING | 502 +++++++++++++++++++++++++++++++++++++ lib/Makefile | 9 + lib/libpwqr.c | 345 ++++++++++++++++++++++++++ 8 files changed, 1573 insertions(+) create mode 100644 .gitignore create mode 100644 Makefile create mode 100644 kernel/Makefile create mode 100644 kernel/pwqr.c create mode 100644 kernel/pwqr.h create mode 100644 lib/COPYING create mode 100644 lib/Makefile create mode 100644 lib/libpwqr.c diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000..32058e5 --- /dev/null +++ b/.gitignore @@ -0,0 +1,8 @@ +*.o +*.ko +*.so +*.mod.c +.*.cmd +.tmp_versions +Module.symvers +modules.order diff --git a/Makefile b/Makefile new file mode 100644 index 0000000..7558a97 --- /dev/null +++ b/Makefile @@ -0,0 +1,5 @@ +all clean: + $(MAKE) -C kernel $@ + $(MAKE) -C lib $@ + +.PHONY: all clean diff --git a/kernel/Makefile b/kernel/Makefile new file mode 100644 index 0000000..94c9f88 --- /dev/null +++ b/kernel/Makefile @@ -0,0 +1,14 @@ +KVERSION = $(shell uname -r) + +obj-m = pwqr.o + +all: pwqr.ko + +pwqr.ko: pwqr.c pwqr.h + $(MAKE) -C /lib/modules/$(KVERSION)/build M=$(PWD) modules + +clean: + $(MAKE) -C /lib/modules/$(KVERSION)/build M=$(PWD) clean + $(RM) test + +.PHONY: all clean diff --git a/kernel/pwqr.c b/kernel/pwqr.c new file mode 100644 index 0000000..0dd026f --- /dev/null +++ b/kernel/pwqr.c @@ -0,0 +1,648 @@ +/* + * Copyright (C) 2012 Pierre Habouzit + * Copyright (C) 2012 Intersec SAS + * + * This file implements the Linux Pthread Workqueue Regulator, and is part + * of the linux kernel. + * + * The Linux Kernel is free software: you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published by + * the Free Software Foundation. + * + * The Linux Kernel 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 Lesser General Public + * License for more details. + * + * You should have received a copy of the GNU General Public License version 2 + * along with The Linux Kernel. If not, see . + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#ifndef CONFIG_PREEMPT_NOTIFIERS +# error PWQ module requires CONFIG_PREEMPT_NOTIFIERS +#endif + +#include "pwqr.h" + +#define PWQR_HASH_BITS 5 +#define PWQR_HASH_SIZE (1 << PWQR_HASH_BITS) + +struct pwqr_task_bucket { + spinlock_t lock; + struct hlist_head tasks; +}; + +struct pwqr_sb { + struct kref kref; + struct rcu_head rcu; + wait_queue_head_t wqh; + pid_t tgid; + + unsigned concurrency; + unsigned registered; + + unsigned running; + unsigned waiting; + unsigned quarantined; + unsigned parked; + unsigned overcommit_wakes; + + unsigned dead; +}; + +struct pwqr_task { + struct preempt_notifier notifier; + struct hlist_node link; + struct rcu_head rcu; + struct task_struct *task; + struct pwqr_sb *sb; +}; + +/* + * Global variables + */ +static struct class *pwqr_class; +static int pwqr_major; +static struct pwqr_task_bucket pwqr_tasks_hash[PWQR_HASH_SIZE]; +static struct preempt_ops pwqr_preempt_running_ops; +static struct preempt_ops pwqr_preempt_blocked_ops; +static struct preempt_ops pwqr_preempt_noop_ops; + +/***************************************************************************** + * Scoreboards + */ + +#define pwqr_sb_lock_irqsave(sb, flags) \ + spin_lock_irqsave(&(sb)->wqh.lock, flags) +#define pwqr_sb_unlock_irqrestore(sb, flags) \ + spin_unlock_irqrestore(&(sb)->wqh.lock, flags) + +static inline void __pwqr_sb_update_state(struct pwqr_sb *sb, int running_delta) +{ + int overcommit; + + sb->running += running_delta; + overcommit = sb->running + sb->waiting - sb->concurrency; + if (overcommit == 0) + return; + + if (overcommit > 0) { + if (overcommit > sb->waiting) { + sb->quarantined += sb->waiting; + sb->waiting = 0; + } else { + sb->quarantined += overcommit; + sb->waiting -= overcommit; + } + } else { + unsigned undercommit = -overcommit; + + if (undercommit < sb->quarantined) { + sb->waiting += undercommit; + sb->quarantined -= undercommit; + } else if (sb->quarantined) { + sb->waiting += sb->quarantined; + sb->quarantined = 0; + } else if (sb->waiting == 0 && sb->parked) { + wake_up_locked(&sb->wqh); + } + } +} + +static struct pwqr_sb *pwqr_sb_create(void) +{ + struct pwqr_sb *sb; + + sb = kzalloc(sizeof(struct pwqr_sb), GFP_KERNEL); + if (sb == NULL) + return ERR_PTR(-ENOMEM); + + kref_init(&sb->kref); + init_waitqueue_head(&sb->wqh); + sb->tgid = current->tgid; + sb->concurrency = num_online_cpus(); + + __module_get(THIS_MODULE); + return sb; +} +static inline void pwqr_sb_get(struct pwqr_sb *sb) +{ + kref_get(&sb->kref); +} + +static void pwqr_sb_finalize(struct rcu_head *rcu) +{ + struct pwqr_sb *sb = container_of(rcu, struct pwqr_sb, rcu); + + module_put(THIS_MODULE); + kfree(sb); +} + +static void pwqr_sb_release(struct kref *kref) +{ + struct pwqr_sb *sb = container_of(kref, struct pwqr_sb, kref); + + call_rcu(&sb->rcu, pwqr_sb_finalize); +} +static inline void pwqr_sb_put(struct pwqr_sb *sb) +{ + kref_put(&sb->kref, pwqr_sb_release); +} + +/***************************************************************************** + * tasks + */ +static inline struct pwqr_task_bucket *task_hbucket(struct task_struct *task) +{ + return &pwqr_tasks_hash[hash_ptr(task, PWQR_HASH_BITS)]; +} + +static struct pwqr_task *pwqr_task_find(struct task_struct *task) +{ + struct pwqr_task_bucket *b = task_hbucket(task); + struct hlist_node *node; + struct pwqr_task *pwqt = NULL; + + spin_lock(&b->lock); + hlist_for_each_entry(pwqt, node, &b->tasks, link) { + if (pwqt->task == task) + break; + } + spin_unlock(&b->lock); + return pwqt; +} + +static struct pwqr_task *pwqr_task_create(struct task_struct *task) +{ + struct pwqr_task_bucket *b = task_hbucket(task); + struct pwqr_task *pwqt; + + pwqt = kmalloc(sizeof(*pwqt), GFP_KERNEL); + if (pwqt == NULL) + return ERR_PTR(-ENOMEM); + + preempt_notifier_init(&pwqt->notifier, &pwqr_preempt_running_ops); + preempt_notifier_register(&pwqt->notifier); + pwqt->task = task; + + spin_lock(&b->lock); + hlist_add_head(&pwqt->link, &b->tasks); + spin_unlock(&b->lock); + + return pwqt; +} + +__cold +static void pwqr_task_detach(struct pwqr_task *pwqt, struct pwqr_sb *sb) +{ + unsigned long flags; + + pwqr_sb_lock_irqsave(sb, flags); + sb->registered--; + if (pwqt->notifier.ops == &pwqr_preempt_running_ops) { + __pwqr_sb_update_state(sb, -1); + } else { + __pwqr_sb_update_state(sb, 0); + } + pwqr_sb_unlock_irqrestore(sb, flags); + pwqr_sb_put(sb); + pwqt->sb = NULL; +} + +__cold +static void pwqr_task_attach(struct pwqr_task *pwqt, struct pwqr_sb *sb) +{ + unsigned long flags; + + pwqr_sb_lock_irqsave(sb, flags); + pwqr_sb_get(pwqt->sb = sb); + sb->registered++; + __pwqr_sb_update_state(sb, 1); + pwqr_sb_unlock_irqrestore(sb, flags); +} + +__cold +static void pwqr_task_release(struct pwqr_task *pwqt, bool from_notifier) +{ + struct pwqr_task_bucket *b = task_hbucket(pwqt->task); + + spin_lock(&b->lock); + hlist_del(&pwqt->link); + spin_unlock(&b->lock); + pwqt->notifier.ops = &pwqr_preempt_noop_ops; + + if (from_notifier) { + /* When called from sched_{out,in}, it's not allowed to + * call preempt_notifier_unregister (or worse kfree()) + * + * Though it's not a good idea to kfree() still registered + * callbacks if we're not dying, it'll panic on the next + * sched_{in,out} call. + */ + BUG_ON(!(pwqt->task->state & TASK_DEAD)); + kfree_rcu(pwqt, rcu); + } else { + preempt_notifier_unregister(&pwqt->notifier); + kfree(pwqt); + } +} + +static void pwqr_task_noop_sched_in(struct preempt_notifier *notifier, int cpu) +{ +} + +static void pwqr_task_noop_sched_out(struct preempt_notifier *notifier, + struct task_struct *next) +{ +} + +static void pwqr_task_blocked_sched_in(struct preempt_notifier *notifier, int cpu) +{ + struct pwqr_task *pwqt = container_of(notifier, struct pwqr_task, notifier); + struct pwqr_sb *sb = pwqt->sb; + unsigned long flags; + + if (unlikely(sb->dead)) { + pwqr_task_detach(pwqt, sb); + pwqr_task_release(pwqt, true); + return; + } + + pwqt->notifier.ops = &pwqr_preempt_running_ops; + pwqr_sb_lock_irqsave(sb, flags); + __pwqr_sb_update_state(sb, 1); + pwqr_sb_unlock_irqrestore(sb, flags); +} + +static void pwqr_task_sched_out(struct preempt_notifier *notifier, + struct task_struct *next) +{ + struct pwqr_task *pwqt = container_of(notifier, struct pwqr_task, notifier); + struct pwqr_sb *sb = pwqt->sb; + struct task_struct *p = pwqt->task; + + if (unlikely(p->state & TASK_DEAD) || unlikely(sb->dead)) { + pwqr_task_detach(pwqt, sb); + pwqr_task_release(pwqt, true); + return; + } + if (p->state == 0 || (p->state & (__TASK_STOPPED | __TASK_TRACED))) + return; + + pwqt->notifier.ops = &pwqr_preempt_blocked_ops; + /* see preempt.h: irq are disabled for sched_out */ + spin_lock(&sb->wqh.lock); + __pwqr_sb_update_state(sb, -1); + spin_unlock(&sb->wqh.lock); +} + +static struct preempt_ops __read_mostly pwqr_preempt_noop_ops = { + .sched_in = pwqr_task_noop_sched_in, + .sched_out = pwqr_task_noop_sched_out, +}; + +static struct preempt_ops __read_mostly pwqr_preempt_running_ops = { + .sched_in = pwqr_task_noop_sched_in, + .sched_out = pwqr_task_sched_out, +}; + +static struct preempt_ops __read_mostly pwqr_preempt_blocked_ops = { + .sched_in = pwqr_task_blocked_sched_in, + .sched_out = pwqr_task_sched_out, +}; + +/***************************************************************************** + * file descriptor + */ +static int pwqr_open(struct inode *inode, struct file *filp) +{ + struct pwqr_sb *sb; + + sb = pwqr_sb_create(); + if (IS_ERR(sb)) + return PTR_ERR(sb); + filp->private_data = sb; + return 0; +} + +static int pwqr_release(struct inode *inode, struct file *filp) +{ + struct pwqr_sb *sb = filp->private_data; + unsigned long flags; + + pwqr_sb_lock_irqsave(sb, flags); + sb->dead = true; + pwqr_sb_unlock_irqrestore(sb, flags); + wake_up_all(&sb->wqh); + pwqr_sb_put(sb); + return 0; +} + +static long +do_pwqr_wait(struct pwqr_sb *sb, struct pwqr_task *pwqt, + int in_pool, struct pwqr_ioc_wait __user *arg) +{ + unsigned long flags; + struct pwqr_ioc_wait wait; + long rc = 0; + u32 uval; + + preempt_notifier_unregister(&pwqt->notifier); + + if (in_pool && copy_from_user(&wait, arg, sizeof(wait))) { + rc = -EFAULT; + goto out; + } + + pwqr_sb_lock_irqsave(sb, flags); + if (sb->running + sb->waiting <= sb->concurrency) { + if (in_pool) { + while (probe_kernel_address(wait.pwqr_uaddr, uval)) { + pwqr_sb_unlock_irqrestore(sb, flags); + rc = get_user(uval, (u32 *)wait.pwqr_uaddr); + if (rc) + goto out; + pwqr_sb_lock_irqsave(sb, flags); + } + + if (uval != (u32)wait.pwqr_ticket) { + rc = -EWOULDBLOCK; + goto out_unlock; + } + } else { + BUG_ON(sb->quarantined != 0); + goto out_unlock; + } + } + + /* @ see */ + if (likely(!sb->dead)) { + DEFINE_WAIT(__wait); + + __wait.flags |= WQ_FLAG_EXCLUSIVE; + + if (in_pool) { + sb->waiting++; + __add_wait_queue(&sb->wqh, &__wait); + } else { + sb->parked++; + __add_wait_queue_tail(&sb->wqh, &__wait); + } + __pwqr_sb_update_state(sb, -1); + set_current_state(TASK_INTERRUPTIBLE); + + do { + if (sb->overcommit_wakes) + break; + if (signal_pending(current)) { + rc = -ERESTARTSYS; + break; + } + spin_unlock_irq(&sb->wqh.lock); + schedule(); + spin_lock_irq(&sb->wqh.lock); + if (in_pool && sb->waiting) + break; + if (sb->running + sb->waiting < sb->concurrency) + break; + } while (likely(!sb->dead)); + + __remove_wait_queue(&sb->wqh, &__wait); + __set_current_state(TASK_RUNNING); + + if (in_pool) { + if (sb->waiting) { + sb->waiting--; + } else { + BUG_ON(!sb->quarantined); + sb->quarantined--; + } + } else { + sb->parked--; + } + __pwqr_sb_update_state(sb, 1); + if (sb->overcommit_wakes) + sb->overcommit_wakes--; + if (sb->waiting + sb->running > sb->concurrency) + rc = -EDQUOT; + } + +out_unlock: + if (unlikely(sb->dead)) + rc = -EBADFD; + pwqr_sb_unlock_irqrestore(sb, flags); +out: + preempt_notifier_register(&pwqt->notifier); + return rc; +} + +static long do_pwqr_unregister(struct pwqr_sb *sb, struct pwqr_task *pwqt) +{ + if (!pwqt) + return -EINVAL; + if (pwqt->sb != sb) + return -ENOENT; + pwqr_task_detach(pwqt, sb); + pwqr_task_release(pwqt, false); + return 0; +} + +static long do_pwqr_set_conc(struct pwqr_sb *sb, int conc) +{ + long old_conc = sb->concurrency; + unsigned long flags; + + pwqr_sb_lock_irqsave(sb, flags); + if (conc <= 0) + conc = num_online_cpus(); + if (conc != old_conc) { + sb->concurrency = conc; + __pwqr_sb_update_state(sb, 0); + } + pwqr_sb_unlock_irqrestore(sb, flags); + + return old_conc; +} + +static long do_pwqr_wake(struct pwqr_sb *sb, int oc, int count) +{ + unsigned long flags; + int nwake; + + if (count < 0) + return -EINVAL; + + pwqr_sb_lock_irqsave(sb, flags); + + if (oc) { + nwake = sb->waiting + sb->quarantined + sb->parked - sb->overcommit_wakes; + if (count > nwake) { + count = nwake; + } else { + nwake = count; + } + sb->overcommit_wakes += count; + } else if (sb->running + sb->overcommit_wakes < sb->concurrency) { + nwake = sb->concurrency - sb->overcommit_wakes - sb->running; + if (count > nwake) { + count = nwake; + } else { + nwake = count; + } + } else { + /* + * This codepath deserves an explanation: when the thread is + * quarantined, for is, really, it's already "parked". Though + * userland doesn't know about, so wake as many threads as + * userlands would have liked to, and let the wakeup tell + * userland those should be parked. + * + * That's why we lie about the number of woken threads, + * really, userlandwise we woke up a thread so that it could + * be parked for real and avoid spurious syscalls. So it's as + * if we woke up 0 threads. + */ + nwake = sb->quarantined; + if (sb->waiting < sb->overcommit_wakes) + nwake -= sb->overcommit_wakes - sb->waiting; + if (nwake > count) + nwake = count; + count = 0; + } + while (nwake-- > 0) + wake_up_locked(&sb->wqh); + pwqr_sb_unlock_irqrestore(sb, flags); + + return count; +} + +static long pwqr_ioctl(struct file *filp, unsigned command, unsigned long arg) +{ + struct pwqr_sb *sb = filp->private_data; + struct task_struct *task = current; + struct pwqr_task *pwqt; + int rc = 0; + + if (sb->tgid != current->tgid) + return -EBADFD; + + switch (command) { + case PWQR_GET_CONC: + return sb->concurrency; + case PWQR_SET_CONC: + return do_pwqr_set_conc(sb, (int)arg); + + case PWQR_WAKE: + case PWQR_WAKE_OC: + return do_pwqr_wake(sb, command == PWQR_WAKE_OC, (int)arg); + + case PWQR_WAIT: + case PWQR_PARK: + case PWQR_REGISTER: + case PWQR_UNREGISTER: + break; + default: + return -EINVAL; + } + + pwqt = pwqr_task_find(task); + if (command == PWQR_UNREGISTER) + return do_pwqr_unregister(sb, pwqt); + + if (pwqt == NULL) { + pwqt = pwqr_task_create(task); + if (IS_ERR(pwqt)) + return PTR_ERR(pwqt); + pwqr_task_attach(pwqt, sb); + } else if (unlikely(pwqt->sb != sb)) { + pwqr_task_detach(pwqt, pwqt->sb); + pwqr_task_attach(pwqt, sb); + } + + switch (command) { + case PWQR_WAIT: + rc = do_pwqr_wait(sb, pwqt, true, (struct pwqr_ioc_wait __user *)arg); + break; + case PWQR_PARK: + rc = do_pwqr_wait(sb, pwqt, false, NULL); + break; + } + + if (unlikely(sb->dead)) { + pwqr_task_detach(pwqt, pwqt->sb); + return -EBADFD; + } + return rc; +} + +static const struct file_operations pwqr_dev_fops = { + .owner = THIS_MODULE, + .open = pwqr_open, + .release = pwqr_release, + .unlocked_ioctl = pwqr_ioctl, +#ifdef CONFIG_COMPAT + .compat_ioctl = pwqr_ioctl, +#endif +}; + +/***************************************************************************** + * module + */ +static int __init pwqr_start(void) +{ + int i; + + for (i = 0; i < PWQR_HASH_SIZE; i++) { + spin_lock_init(&pwqr_tasks_hash[i].lock); + INIT_HLIST_HEAD(&pwqr_tasks_hash[i].tasks); + } + + /* Register as a character device */ + pwqr_major = register_chrdev(0, "pwqr", &pwqr_dev_fops); + if (pwqr_major < 0) { + printk(KERN_ERR "pwqr: register_chrdev() failed\n"); + return pwqr_major; + } + + /* Create a device node */ + pwqr_class = class_create(THIS_MODULE, PWQR_DEVICE_NAME); + if (IS_ERR(pwqr_class)) { + printk(KERN_ERR "pwqr: Error creating raw class\n"); + unregister_chrdev(pwqr_major, PWQR_DEVICE_NAME); + return PTR_ERR(pwqr_class); + } + device_create(pwqr_class, NULL, MKDEV(pwqr_major, 0), NULL, PWQR_DEVICE_NAME); + printk(KERN_INFO "pwqr: PThreads Work Queues Regulator v1 loaded"); + return 0; +} + +static void __exit pwqr_end(void) +{ + rcu_barrier(); + device_destroy(pwqr_class, MKDEV(pwqr_major, 0)); + class_destroy(pwqr_class); + unregister_chrdev(pwqr_major, PWQR_DEVICE_NAME); +} + +module_init(pwqr_start); +module_exit(pwqr_end); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Pierre Habouzit "); +MODULE_DESCRIPTION("PThreads Work Queues Regulator"); + +// vim:noet:sw=8:cinoptions+=\:0,L-1,=1s: diff --git a/kernel/pwqr.h b/kernel/pwqr.h new file mode 100644 index 0000000..a7aa086 --- /dev/null +++ b/kernel/pwqr.h @@ -0,0 +1,42 @@ +/* + * Copyright (C) 2012 Pierre Habouzit + * Copyright (C) 2012 Intersec SAS + * + * This file implements the Linux Pthread Workqueue Regulator, and is part + * of the linux kernel. + * + * The Linux Kernel is free software: you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published by + * the Free Software Foundation. + * + * The Linux Kernel 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 Lesser General Public + * License for more details. + * + * You should have received a copy of the GNU General Public License version 2 + * along with The Linux Kernel. If not, see . + */ + +#ifndef _LINUX_PWQR_H +#define _LINUX_PWQR_H +#include + +#define PWQR_DEVICE_NAME "pwq" +#define PWQR_IO '}' + +struct pwqr_ioc_wait { + int pwqr_ticket; + void *pwqr_uaddr; +}; + +#define PWQR_GET_CONC _IO (PWQR_IO, 0) +#define PWQR_SET_CONC _IO (PWQR_IO, 1) +#define PWQR_REGISTER _IO (PWQR_IO, 2) +#define PWQR_UNREGISTER _IO (PWQR_IO, 3) +#define PWQR_WAKE _IO (PWQR_IO, 4) +#define PWQR_WAKE_OC _IO (PWQR_IO, 5) +#define PWQR_WAIT _IOW(PWQR_IO, 6, struct pwqr_ioc_wait) +#define PWQR_PARK _IO (PWQR_IO, 7) + +#endif diff --git a/lib/COPYING b/lib/COPYING new file mode 100644 index 0000000..4362b49 --- /dev/null +++ b/lib/COPYING @@ -0,0 +1,502 @@ + GNU LESSER GENERAL PUBLIC LICENSE + Version 2.1, February 1999 + + Copyright (C) 1991, 1999 Free Software Foundation, Inc. + 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + Everyone is permitted to copy and distribute verbatim copies + of this license document, but changing it is not allowed. + +[This is the first released version of the Lesser GPL. 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See the + * GNU Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public License + * along with The Linux Pthread Workqueue Regultaor. + * If not, see . + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "../kernel/pwqr.h" + +#define INPOOL 0 +#define PARKED 1 +#define PARKED_MAX 16 +#define THREADS_MAX 128 /* something dynamic is probably better */ + +/* Compiler stuff {{{ */ + +#if defined(__x86_64__) +# define mb() asm volatile("mfence":::"memory") +#elif defined(__i386__) +# define mb() asm volatile("lock; addl $0,0(%%esp)":::"memory") +#else +# error unsupported architecture +#endif + +#define container_of(obj, type_t, member) \ + ({ const typeof(((type_t *)0)->member) *__mptr = (obj); \ + ((type_t *)((char *)__mptr) - offsetof(type_t, member)); }) +#define likely(expr) __builtin_expect(!!(expr), 1) +#define unlikely(expr) __builtin_expect((expr), 0) + +#define barrier() asm volatile("":::"memory") +#define access_once(x) (*(volatile typeof(x) *)&(x)) + +#define atomic_fetch_and_add(ptr, n) __sync_fetch_and_add(ptr, n) +#define atomic_add(ptr, n) (void)atomic_fetch_and_add(ptr, n) +#define atomic_fetch_and_sub(ptr, n) __sync_fetch_and_sub(ptr, n) +#define atomic_sub(ptr, n) (void)atomic_fetch_and_sub(ptr, n) + +#define ALWAYS_INLINE __attribute__((always_inline)) inline + +/* }}} */ +/* pwqr wrapping {{{ */ + +static int pwqr_create(void) +{ + return open("/dev/"PWQR_DEVICE_NAME, O_RDWR); +} + +static int pwqr_ctl(int fd, int op, int val, void *uaddr) +{ + struct pwqr_ioc_wait wait; + + switch (op) { + case PWQR_GET_CONC: + case PWQR_REGISTER: + case PWQR_UNREGISTER: + case PWQR_PARK: + return ioctl(fd, op); + case PWQR_SET_CONC: + case PWQR_WAKE: + case PWQR_WAKE_OC: + return ioctl(fd, op, val); + case PWQR_WAIT: + wait.pwqr_ticket = val; + wait.pwqr_uaddr = uaddr; + return ioctl(fd, op, &wait); + default: + errno = EINVAL; + return -1; + } +} + +/* }}} */ + +static struct { + int fd; + /* atomic */ int spinlock; + /* atomic */ int nthreads; + /* atomic */ int waiters; + /* atomic */ int parked; + + union { + struct { +#if __BYTE_ORDER == __LITTLE_ENDIAN + /* atomic */ uint32_t lo; + /* atomic */ uint32_t hi; +#elif __BYTE_ORDER == __BIG_ENDIAN + /* atomic */ uint32_t hi; + /* atomic */ uint32_t lo; +#else +#error Unsupported endianness +#endif + }; + uint64_t ticket; + }; +} pwqr_g = { + .fd = -1, +}; + +static ALWAYS_INLINE void pwqr_lock(void) +{ + while (unlikely(__sync_lock_test_and_set(&pwqr_g.spinlock, 1))) + sched_yield(); +} + +static ALWAYS_INLINE void pwqr_unlock(void) +{ + __sync_lock_release(&pwqr_g.spinlock); +} + +static ALWAYS_INLINE uint64_t pwqr_get_ticket(void) +{ + mb(); + return access_once(pwqr_g.ticket); +} + +static ALWAYS_INLINE void pwqr_signal_n(int n) +{ +#if ULONG_MAX == UINT32_MAX + /* + * We don't know how slow things are between a pwqr_get() and a + * pwqr_wait. Hence it's not safe to assume the "count" will never + * rotate fully between the two. + * + * In 64bits mode, well, we have 64-bits atomic increments and all is + * fine. In 32bits mode, we increment the high word manually every 2^24 + * low-word increment. + * + * This assumes that at least one of the 256 threads that will try to + * perform the "hi" increment won't be stalled between deciding the modulo + * is zero and the increment itself for an almost full cycle (2^32 - 2^24) + * of the low word counter. + */ + if (unlikely(atomic_fetch_and_add(&pwqr_g.lo, 1) % (1U << 24) == 0)) + atomic_add(&pwqr_g.hi, 1); +#else + atomic_add(&pwqr_g.ticket, 1); +#endif + if (atomic_fetch_and_add(&pwqr_g.waiters, 0)) + pwqr_ctl(pwqr_g.fd, PWQR_WAKE, n, NULL); +} +static ALWAYS_INLINE void pwqr_signal(void) +{ + pwqr_signal_n(1); +} + +static ALWAYS_INLINE void pwqr_signal_relaxed_n(int n) +{ + if (access_once(pwqr_g.waiters)) + pwqr_signal_n(n); +} +static ALWAYS_INLINE void pwqr_signal_relaxed(void) +{ + pwqr_signal_relaxed_n(1); +} + + +/* returns: + - INPOOL if we were woken to run jobs. + - PARKED if we were woken to be parked (possibly consume overcommit stuff) + */ +static void pwqr_do_wait_cleanup(void *arg) +{ + atomic_sub(&pwqr_g.waiters, 1); +} +static int pwqr_do_wait(uint64_t ticket) +{ + int canceltype, rc; + + mb(); +#if ULONG_MAX == UINT32_MAX + if ((unsigned)(ticket >> 32) != access_once(pwqr_g.hi)) + return INPOOL; +#else + if (ticket != access_once(pwqr_g.ticket)) + return INPOOL; +#endif + + atomic_add(&pwqr_g.waiters, 1); + pthread_cleanup_push(&pwqr_do_wait_cleanup, NULL); + pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, &canceltype); + + rc = pwqr_ctl(pwqr_g.fd, PWQR_WAIT, ticket, &pwqr_g.lo); + if (rc < 0) { + if (errno == EINTR) { + rc = INPOOL; + } else if (errno == EDQUOT) { + rc = PARKED; + } else { + assert (errno == EBADFD); + } + } + + pthread_setcanceltype(canceltype, NULL); + pthread_cleanup_pop(1); +} + +/* returns INPOOL if the thread is to run some jobs or go to WAIT + * returns -1 if the pwqr_g.fd is broken + */ +static void pwqr_do_park_cleanup(void *arg) +{ + atomic_sub(&pwqr_g.parked, 1); +} +static void pwqr_spawn_thread(int initial_state, int count); +static int pwqr_do_park(void) +{ + int canceltype, rc = -1; + + if (atomic_fetch_and_add(&pwqr_g.parked, 1) > PARKED_MAX) { + atomic_sub(&pwqr_g.parked, 1); + return -1; + } + + pthread_cleanup_push(&pwqr_do_park_cleanup, NULL); + pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, &canceltype); + + for (;;) { +#ifdef PSEUDO_CODE + while ((job = find_some_job(OC_JOB))) + run_job(job); +#endif + + if ((rc = pwqr_ctl(pwqr_g.fd, PWQR_PARK, 0, NULL)) == 0) { + if (atomic_fetch_and_sub(&pwqr_g.parked, 1) == 0) { + pwqr_spawn_thread(PARKED, 1); + } + break; + } + + if (rc < 0) { + if (errno == EBADFD) { + atomic_sub(&pwqr_g.parked, 1); + return -1; + } + assert (errno == EINTR || errno == EDQUOT); + continue; + } + } + + pthread_setcanceltype(canceltype, NULL); + pthread_cleanup_pop(0); + return rc; +} + +static void pwqr_main_cleanup(void *arg) +{ + atomic_sub(&pwqr_g.nthreads, 1); +} +static void *pwqr_main(void *arg) +{ + int state = (long)arg; + + if (atomic_fetch_and_add(&pwqr_g.nthreads, 1) > THREADS_MAX) + goto out; + + pthread_cleanup_push(&pwqr_main_cleanup, NULL); + if (pwqr_ctl(pwqr_g.fd, PWQR_REGISTER, 0, NULL) < 0) + goto out; + + do { + uint64_t ticket; + + if (state == PARKED && (state = pwqr_do_park()) < 0) + break; +#ifdef PSEUDO_CODE + while ((job = find_some_job(ANY_JOB))) + run_job(job); +#endif + ticket = pwqr_get_ticket(); +#ifdef PSEUDO_CODE + if ((job = find_some_job(ANY_JOB))) { + run_job(job); + continue; + } +#endif + state = pwqr_do_wait(ticket); + } while (state >= 0); + + out: + pthread_cleanup_pop(1); + return NULL; +} + +static void pwqr_spawn_thread(int initial_state, int count) +{ + pthread_t thr; + pthread_attr_t attr; + + pthread_attr_init(&attr); + pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); + while (count-- > 0) + pthread_create(&thr, &attr, pwqr_main, (void *)(long)initial_state); + pthread_attr_destroy(&attr); +} + +__attribute__((cold, noinline, unused)) +static int _pthread_workqueue_init_np(void) +{ + int rc = 0, fd, n; + + pwqr_lock(); + if (pwqr_g.fd >= 0) + goto out; + + fd = pwqr_create(); + if (fd < 0) { + rc = -1; + goto out; + } + + pwqr_g.fd = fd; + n = pwqr_ctl(pwqr_g.fd, PWQR_GET_CONC, 0, NULL) + 4; + pwqr_spawn_thread(INPOOL, n); + pwqr_spawn_thread(PARKED, 4); + + out: + pwqr_unlock(); + return rc; +} -- 2.20.1