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Date: Fri, 4 Jul 2008 15:58:47 +0200 From: Andrea Righi <righi.andrea@...il.com> To: Balbir Singh <balbir@...ux.vnet.ibm.com>, Paul Menage <menage@...gle.com> Cc: Carl Henrik Lunde <chlunde@...g.uio.no>, axboe@...nel.dk, matt@...ehost.com, roberto@...it.it, randy.dunlap@...cle.com, Divyesh Shah <dpshah@...gle.com>, subrata@...ux.vnet.ibm.com, eric.rannaud@...il.com, akpm@...ux-foundation.org, containers@...ts.linux-foundation.org, linux-kernel@...r.kernel.org, Andrea Righi <righi.andrea@...il.com> Subject: [PATCH 2/3] i/o bandwidth controller infrastructure This is the core io-throttle kernel infrastructure. It creates the basic interfaces to cgroups and implements the I/O measurement and throttling functions. Signed-off-by: Andrea Righi <righi.andrea@...il.com> --- block/Makefile | 2 + block/blk-io-throttle.c | 529 +++++++++++++++++++++++++++++++++++++++ include/linux/blk-io-throttle.h | 14 + include/linux/cgroup_subsys.h | 6 + init/Kconfig | 10 + 5 files changed, 561 insertions(+), 0 deletions(-) create mode 100644 block/blk-io-throttle.c create mode 100644 include/linux/blk-io-throttle.h diff --git a/block/Makefile b/block/Makefile index 5a43c7d..8dec69b 100644 --- a/block/Makefile +++ b/block/Makefile @@ -14,3 +14,5 @@ obj-$(CONFIG_IOSCHED_CFQ) += cfq-iosched.o obj-$(CONFIG_BLK_DEV_IO_TRACE) += blktrace.o obj-$(CONFIG_BLOCK_COMPAT) += compat_ioctl.o + +obj-$(CONFIG_CGROUP_IO_THROTTLE) += blk-io-throttle.o diff --git a/block/blk-io-throttle.c b/block/blk-io-throttle.c new file mode 100644 index 0000000..caf740a --- /dev/null +++ b/block/blk-io-throttle.c @@ -0,0 +1,529 @@ +/* + * blk-io-throttle.c + * + * This program 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. + * + * This program 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 this program; if not, write to the + * Free Software Foundation, Inc., 59 Temple Place - Suite 330, + * Boston, MA 021110-1307, USA. + * + * Copyright (C) 2008 Andrea Righi <righi.andrea@...il.com> + */ + +#include <linux/init.h> +#include <linux/module.h> +#include <linux/cgroup.h> +#include <linux/slab.h> +#include <linux/gfp.h> +#include <linux/err.h> +#include <linux/sched.h> +#include <linux/genhd.h> +#include <linux/fs.h> +#include <linux/jiffies.h> +#include <linux/hardirq.h> +#include <linux/list.h> +#include <linux/spinlock.h> +#include <linux/uaccess.h> +#include <linux/blk-io-throttle.h> + +/** + * struct iothrottle_node - throttling rule of a single block device + * @node: list of per block device throttling rules + * @dev: block device number, used as key in the list + * @iorate: max i/o bandwidth (in bytes/s) + * @strategy: throttling strategy (0 = leaky bucket, 1 = token bucket) + * @timestamp: timestamp of the last I/O request (in jiffies) + * @stat: i/o activity counter (leaky bucket only) + * @bucket_size: bucket size in bytes (token bucket only) + * @token: token counter (token bucket only) + * + * Define a i/o throttling rule for a single block device. + * + * NOTE: limiting rules always refer to dev_t; if a block device is unplugged + * the limiting rules defined for that device persist and they are still valid + * if a new device is plugged and it uses the same dev_t number. + */ +struct iothrottle_node { + struct list_head node; + dev_t dev; + u64 iorate; + long strategy; + unsigned long timestamp; + atomic_long_t stat; + s64 bucket_size; + atomic_long_t token; +}; + +/** + * struct iothrottle - throttling rules for a cgroup + * @css: pointer to the cgroup state + * @lock: spinlock used to protect write operations in the list + * @list: list of iothrottle_node elements + * + * Define multiple per-block device i/o throttling rules. + * Note: the list of the throttling rules is protected by RCU locking. + */ +struct iothrottle { + struct cgroup_subsys_state css; + spinlock_t lock; + struct list_head list; +}; + +static inline struct iothrottle *cgroup_to_iothrottle(struct cgroup *cont) +{ + return container_of(cgroup_subsys_state(cont, iothrottle_subsys_id), + struct iothrottle, css); +} + +static inline struct iothrottle *task_to_iothrottle(struct task_struct *task) +{ + return container_of(task_subsys_state(task, iothrottle_subsys_id), + struct iothrottle, css); +} + +/* + * Note: called with rcu_read_lock() held. + */ +static struct iothrottle_node * +iothrottle_search_node(const struct iothrottle *iot, dev_t dev) +{ + struct iothrottle_node *n; + + list_for_each_entry_rcu(n, &iot->list, node) + if (n->dev == dev) + return n; + return NULL; +} + +/* + * Note: called with iot->lock held. + */ +static inline void iothrottle_insert_node(struct iothrottle *iot, + struct iothrottle_node *n) +{ + list_add_rcu(&n->node, &iot->list); +} + +/* + * Note: called with iot->lock held. + */ +static inline struct iothrottle_node * +iothrottle_replace_node(struct iothrottle *iot, struct iothrottle_node *old, + struct iothrottle_node *new) +{ + list_replace_rcu(&old->node, &new->node); + return old; +} + +/* + * Note: called with iot->lock held. + */ +static struct iothrottle_node * +iothrottle_delete_node(struct iothrottle *iot, dev_t dev) +{ + struct iothrottle_node *n; + + list_for_each_entry_rcu(n, &iot->list, node) + if (n->dev == dev) { + list_del_rcu(&n->node); + return n; + } + return NULL; +} + +/* + * Note: called from kernel/cgroup.c with cgroup_lock() held. + */ +static struct cgroup_subsys_state * +iothrottle_create(struct cgroup_subsys *ss, struct cgroup *cont) +{ + struct iothrottle *iot; + + iot = kmalloc(sizeof(*iot), GFP_KERNEL); + if (unlikely(!iot)) + return ERR_PTR(-ENOMEM); + + INIT_LIST_HEAD(&iot->list); + spin_lock_init(&iot->lock); + + return &iot->css; +} + +/* + * Note: called from kernel/cgroup.c with cgroup_lock() held. + */ +static void iothrottle_destroy(struct cgroup_subsys *ss, struct cgroup *cont) +{ + struct iothrottle_node *n, *p; + struct iothrottle *iot = cgroup_to_iothrottle(cont); + + /* + * don't worry about locking here, at this point there must be not any + * reference to the list. + */ + list_for_each_entry_safe(n, p, &iot->list, node) + kfree(n); + kfree(iot); +} + +static ssize_t iothrottle_read(struct cgroup *cont, struct cftype *cft, + struct file *file, char __user *userbuf, + size_t nbytes, loff_t *ppos) +{ + struct iothrottle *iot; + char *buffer; + int s = 0; + struct iothrottle_node *n; + ssize_t ret; + + buffer = kmalloc(nbytes + 1, GFP_KERNEL); + if (!buffer) + return -ENOMEM; + + cgroup_lock(); + if (cgroup_is_removed(cont)) { + ret = -ENODEV; + goto out; + } + + iot = cgroup_to_iothrottle(cont); + rcu_read_lock(); + list_for_each_entry_rcu(n, &iot->list, node) { + unsigned long delta; + + BUG_ON(!n->dev); + delta = jiffies_to_msecs((long)jiffies - (long)n->timestamp); + s += scnprintf(buffer + s, nbytes - s, + "%u %u %llu %li %li %lli %li %lu\n", + MAJOR(n->dev), MINOR(n->dev), n->iorate, + n->strategy, atomic_long_read(&n->stat), + n->bucket_size, atomic_long_read(&n->token), + delta); + } + rcu_read_unlock(); + ret = simple_read_from_buffer(userbuf, nbytes, ppos, buffer, s); +out: + cgroup_unlock(); + kfree(buffer); + return ret; +} + +static dev_t devname2dev_t(const char *buf) +{ + struct block_device *bdev; + dev_t dev = 0; + struct gendisk *disk; + int part; + + /* use a lookup to validate the block device */ + bdev = lookup_bdev(buf); + if (IS_ERR(bdev)) + return 0; + + /* only entire devices are allowed, not single partitions */ + disk = get_gendisk(bdev->bd_dev, &part); + if (disk && !part) { + BUG_ON(!bdev->bd_inode); + dev = bdev->bd_inode->i_rdev; + } + bdput(bdev); + + return dev; +} + +/* + * The userspace input string must use the following syntax: + * + * device:bw-limit:strategy:bucket-size + */ +static int iothrottle_parse_args(char *buf, size_t nbytes, + dev_t *dev, u64 *iorate, + long *strategy, s64 *bucket_size) +{ + char *ioratep, *strategyp, *bucket_sizep; + int ret; + + ioratep = memchr(buf, ':', nbytes); + if (!ioratep) + return -EINVAL; + *ioratep++ = '\0'; + + strategyp = memchr(ioratep, ':', buf + nbytes - ioratep); + if (!strategyp) + return -EINVAL; + *strategyp++ = '\0'; + + bucket_sizep = memchr(strategyp, ':', buf + nbytes - strategyp); + if (!bucket_sizep) + return -EINVAL; + *bucket_sizep++ = '\0'; + + /* i/o bandwidth limit (0 to delete a limiting rule) */ + ret = strict_strtoull(ioratep, 10, iorate); + if (ret < 0) + return ret; + *iorate = ALIGN(*iorate, 1024); + + /* throttling strategy */ + ret = strict_strtol(strategyp, 10, strategy); + if (ret < 0) + return ret; + + /* bucket size */ + ret = strict_strtoll(bucket_sizep, 10, bucket_size); + if (ret < 0) + return ret; + if (*bucket_size < 0) + return -EINVAL; + *bucket_size = ALIGN(*bucket_size, 1024); + + /* block device number */ + *dev = devname2dev_t(buf); + if (!*dev) + return -EINVAL; + + return 0; +} + +static ssize_t iothrottle_write(struct cgroup *cont, struct cftype *cft, + struct file *file, const char __user *userbuf, + size_t nbytes, loff_t *ppos) +{ + struct iothrottle *iot; + struct iothrottle_node *n, *newn = NULL; + char *buffer, *s; + dev_t dev; + u64 iorate; + long strategy; + s64 bucket_size; + int ret; + + if (!nbytes) + return -EINVAL; + + /* Upper limit on largest io-throttle rule string user might write. */ + if (nbytes > 1024) + return -E2BIG; + + buffer = kmalloc(nbytes + 1, GFP_KERNEL); + if (!buffer) + return -ENOMEM; + + ret = strncpy_from_user(buffer, userbuf, nbytes); + if (ret < 0) + goto out1; + buffer[nbytes] = '\0'; + s = strstrip(buffer); + + ret = iothrottle_parse_args(s, nbytes, &dev, &iorate, + &strategy, &bucket_size); + if (ret) + goto out1; + + if (iorate) { + newn = kmalloc(sizeof(*newn), GFP_KERNEL); + if (!newn) { + ret = -ENOMEM; + goto out1; + } + newn->dev = dev; + newn->iorate = iorate; + newn->strategy = strategy; + newn->bucket_size = bucket_size; + newn->timestamp = jiffies; + atomic_long_set(&newn->stat, 0); + atomic_long_set(&newn->token, 0); + } + + cgroup_lock(); + if (cgroup_is_removed(cont)) { + ret = -ENODEV; + goto out2; + } + + iot = cgroup_to_iothrottle(cont); + spin_lock(&iot->lock); + if (!iorate) { + /* Delete a block device limiting rule */ + n = iothrottle_delete_node(iot, dev); + goto out3; + } + n = iothrottle_search_node(iot, dev); + if (n) { + /* Update a block device limiting rule */ + iothrottle_replace_node(iot, n, newn); + goto out3; + } + /* Add a new block device limiting rule */ + iothrottle_insert_node(iot, newn); +out3: + ret = nbytes; + spin_unlock(&iot->lock); + if (n) { + synchronize_rcu(); + kfree(n); + } +out2: + cgroup_unlock(); +out1: + kfree(buffer); + return ret; +} + +static struct cftype files[] = { + { + .name = "bandwidth", + .read = iothrottle_read, + .write = iothrottle_write, + }, +}; + +static int iothrottle_populate(struct cgroup_subsys *ss, struct cgroup *cont) +{ + return cgroup_add_files(cont, ss, files, ARRAY_SIZE(files)); +} + +struct cgroup_subsys iothrottle_subsys = { + .name = "blockio", + .create = iothrottle_create, + .destroy = iothrottle_destroy, + .populate = iothrottle_populate, + .subsys_id = iothrottle_subsys_id, +}; + +/* + * Note: called with rcu_read_lock() held. + */ +static unsigned long leaky_bucket(struct iothrottle_node *n, size_t bytes) +{ + unsigned long delta, t; + long sleep; + + /* Account the i/o activity */ + atomic_long_add(bytes, &n->stat); + + /* Evaluate if we need to throttle the current process */ + delta = (long)jiffies - (long)n->timestamp; + if (!delta) + return 0; + + /* + * NOTE: n->iorate cannot be set to zero here, iorate can only change + * via the userspace->kernel interface that in case of update fully + * replaces the iothrottle_node pointer in the list, using the RCU way. + */ + t = usecs_to_jiffies(atomic_long_read(&n->stat) + * USEC_PER_SEC / n->iorate); + if (!t) + return 0; + + sleep = t - delta; + if (unlikely(sleep > 0)) + return sleep; + + /* Reset i/o statistics */ + atomic_long_set(&n->stat, 0); + /* + * NOTE: be sure i/o statistics have been resetted before updating the + * timestamp, otherwise a very small time delta may possibly be read by + * another CPU w.r.t. accounted i/o statistics, generating unnecessary + * long sleeps. + */ + smp_wmb(); + n->timestamp = jiffies; + return 0; +} + +/* + * Note: called with rcu_read_lock() held. + * XXX: need locking in order to evaluate a consistent sleep??? + */ +static unsigned long token_bucket(struct iothrottle_node *n, size_t bytes) +{ + unsigned long iorate = n->iorate / MSEC_PER_SEC; + unsigned long delta; + long tok; + + BUG_ON(!iorate); + + atomic_long_sub(bytes, &n->token); + delta = jiffies_to_msecs((long)jiffies - (long)n->timestamp); + n->timestamp = jiffies; + tok = atomic_long_read(&n->token); + if (delta && tok < n->bucket_size) { + tok += delta * iorate; + pr_debug("io-throttle: adding %lu tokens\n", delta * iorate); + if (tok > n->bucket_size) + tok = n->bucket_size; + atomic_long_set(&n->token, tok); + } + atomic_long_set(&n->token, tok); + + return (tok < 0) ? msecs_to_jiffies(-tok / iorate) : 0; +} + +/** + * cgroup_io_throttle() - account and throttle i/o activity + * @bdev: block device involved for the i/o. + * @bytes: size in bytes of the i/o operation. + * @can_sleep: used to set to 1 if we're in a sleep()able context, 0 + * otherwise; into a non-sleep()able context we only account the + * i/o activity without applying any throttling sleep. + * + * This is the core of the block device i/o bandwidth controller. This function + * must be called by any function that generates i/o activity (directly or + * indirectly). It provides both i/o accounting and throttling functionalities; + * throttling is disabled if @can_sleep is set to 0. + **/ +void cgroup_io_throttle(struct block_device *bdev, size_t bytes, int can_sleep) +{ + struct iothrottle *iot; + struct iothrottle_node *n; + dev_t dev; + unsigned long sleep; + + if (unlikely(!bdev)) + return; + + iot = task_to_iothrottle(current); + if (unlikely(!iot)) + return; + + BUG_ON(!bdev->bd_inode || !bdev->bd_disk); + dev = MKDEV(MAJOR(bdev->bd_inode->i_rdev), bdev->bd_disk->first_minor); + + rcu_read_lock(); + n = iothrottle_search_node(iot, dev); + if (!n || !n->iorate) { + rcu_read_unlock(); + return; + } + switch (n->strategy) { + case 0: + sleep = leaky_bucket(n, bytes); + break; + case 1: + sleep = token_bucket(n, bytes); + break; + default: + sleep = 0; + } + if (unlikely(can_sleep && sleep)) { + rcu_read_unlock(); + pr_debug("io-throttle: task %p (%s) must sleep %lu jiffies\n", + current, current->comm, sleep); + schedule_timeout_killable(sleep); + return; + } + rcu_read_unlock(); +} +EXPORT_SYMBOL(cgroup_io_throttle); diff --git a/include/linux/blk-io-throttle.h b/include/linux/blk-io-throttle.h new file mode 100644 index 0000000..0fe7430 --- /dev/null +++ b/include/linux/blk-io-throttle.h @@ -0,0 +1,14 @@ +#ifndef BLK_IO_THROTTLE_H +#define BLK_IO_THROTTLE_H + +#ifdef CONFIG_CGROUP_IO_THROTTLE +extern void +cgroup_io_throttle(struct block_device *bdev, size_t bytes, int can_sleep); +#else +static inline void +cgroup_io_throttle(struct block_device *bdev, size_t bytes, int can_sleep) +{ +} +#endif /* CONFIG_CGROUP_IO_THROTTLE */ + +#endif /* BLK_IO_THROTTLE_H */ diff --git a/include/linux/cgroup_subsys.h b/include/linux/cgroup_subsys.h index e287745..0caf3c2 100644 --- a/include/linux/cgroup_subsys.h +++ b/include/linux/cgroup_subsys.h @@ -48,3 +48,9 @@ SUBSYS(devices) #endif /* */ + +#ifdef CONFIG_CGROUP_IO_THROTTLE +SUBSYS(iothrottle) +#endif + +/* */ diff --git a/init/Kconfig b/init/Kconfig index 6199d11..3117d99 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -306,6 +306,16 @@ config CGROUP_DEVICE Provides a cgroup implementing whitelists for devices which a process in the cgroup can mknod or open. +config CGROUP_IO_THROTTLE + bool "Enable cgroup I/O throttling (EXPERIMENTAL)" + depends on CGROUPS && EXPERIMENTAL + help + This allows to limit the maximum I/O bandwidth for specific + cgroup(s). + See Documentation/controllers/io-throttle.txt for more information. + + If unsure, say N. + config CPUSETS bool "Cpuset support" depends on SMP && CGROUPS -- 1.5.4.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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