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SubjectRe: [RFC] [PATCH] cgroup: limit network bandwidth
An approach that we've been experimenting with at Google is much simpler:

- add a "network class id" subsystem, that lets you associated an id
with each cgroup

- propagate this id to sockets created by that cgroup, and from there
to packets sent/received on that socket

- add a new traffic filter that can select based on a packet's cgroup class id

This is a very small amount of kernel code, but it then lets userspace
set up whatever queues/filters/classes it wants using the standard
Linux traffic API, rather than creating a new traffic control API
that's much more limited. So you can easily do things like controlling
guarantees and limits, have different behaviour for local and remote
packets, have packet/byte accounting for different flow classes,
filter on ToS bits in order to let the cgroup prioritize its own
traffic, etc.

We also have plans (have had for months in fact, but haven't had time
for it yet) to let the cgroup network id be selected on in iptables
rules, and possibly add a new iptable for events such as listen(),
bind(), and connect(), to allow very easy control over what network
connections a cgroup can access. This would let you use the full power
of the existing packet/connection matching available in the standard
iptables rules without having to add a new complex (but still limited)
API.

Paul

On Jan 23, 2008 1:09 AM, Andrea Righi <righiandr@users.sourceforge.net> wrote:
> Allow to limit the network bandwidth for specific process containers (cgroups)
> imposing additional delays in the sockets' sendmsg()/recvmsg() calls made by
> those processes that exceed the limits defined in the control group filesystem.
>
> Example:
> # mkdir /dev/cgroup
> # mount -t cgroup -onet net /dev/cgroup
> # cd /dev/cgroup
> # mkdir foo
> --> the cgroup foo has been created
> # /bin/echo $$ > foo/tasks
> # /bin/echo 1024 > foo/net.tcp
> # /bin/echo 2048 > foo/net.tot
> # sh
> --> the subshell 'sh' is running in cgroup "foo" that has a maximum network
> bandwidth for TCP traffic of 1MB/s and 2MB/s for total network
> activities.
>
> The netlimit approach can be easily extended to support additional network
> protocols or different socket families or types (PF_UNIX, PF_BLUETOOTH,
> SOCK_SEQPACKET, etc.).
>
> Signed-off-by: Andrea Righi <a.righi@cineca.it>
> ---
>
> diff -urpN linux-2.6.24-rc8/include/linux/cgroup_netlimit.h linux-2.6.24-rc8-cgroup-netlimit/include/linux/cgroup_netlimit.h
> --- linux-2.6.24-rc8/include/linux/cgroup_netlimit.h 1970-01-01 01:00:00.000000000 +0100
> +++ linux-2.6.24-rc8-cgroup-netlimit/include/linux/cgroup_netlimit.h 2008-01-22 21:36:15.000000000 +0100
> @@ -0,0 +1,29 @@
> +#ifndef CGROUP_NETLIMIT_H
> +#define CGROUP_NETLIMIT_H
> +
> +enum {
> + CGROUP_NETLIMIT_TOT,
> + CGROUP_NETLIMIT_TCP,
> + CGROUP_NETLIMIT_UDP,
> + CGROUP_NETLIMIT_RAW,
> + /* This sets the size of the different netlimit types */
> + CGROUP_NETLIMIT_END,
> +};
> +
> +#define CGROUP_NETLIMIT_FILE(_x, _y) \
> + { \
> + .name = _x, \
> + .read = netlimit_read, \
> + .write_uint = netlimit_write_uint, \
> + .private = _y, \
> + }
> +
> +#ifdef CONFIG_CGROUP_NETLIMIT
> +extern void cgroup_nl_acct(int limit_id, size_t bytes);
> +extern void cgroup_nl_throttle(int limit_id, int interruptible);
> +#else
> +static inline void cgroup_nl_acct(int limit_id, size_t bytes) { }
> +static inline void cgroup_nl_throttle(int limit_id, int interruptible) { }
> +#endif /* CONFIG_CGROUP_NETLIMIT */
> +
> +#endif
> diff -urpN linux-2.6.24-rc8/include/linux/cgroup_subsys.h linux-2.6.24-rc8-cgroup-netlimit/include/linux/cgroup_subsys.h
> --- linux-2.6.24-rc8/include/linux/cgroup_subsys.h 2008-01-16 05:22:48.000000000 +0100
> +++ linux-2.6.24-rc8-cgroup-netlimit/include/linux/cgroup_subsys.h 2008-01-22 14:42:17.000000000 +0100
> @@ -37,3 +37,9 @@ SUBSYS(cpuacct)
>
> /* */
>
> +#ifdef CONFIG_CGROUP_NETLIMIT
> +SUBSYS(netlimit)
> +#endif
> +
> +/* */
> +
> diff -urpN linux-2.6.24-rc8/init/Kconfig linux-2.6.24-rc8-cgroup-netlimit/init/Kconfig
> --- linux-2.6.24-rc8/init/Kconfig 2008-01-16 05:22:48.000000000 +0100
> +++ linux-2.6.24-rc8-cgroup-netlimit/init/Kconfig 2008-01-23 00:44:04.000000000 +0100
> @@ -313,6 +313,15 @@ config CGROUP_NS
> for instance virtual servers and checkpoint/restart
> jobs.
>
> +config CGROUP_NETLIMIT
> + bool "Enable cgroup network bandwidth limitinig (EXPERIMENTAL)"
> + depends on EXPERIMENTAL && CGROUPS
> + help
> + This allows to define network bandwidth limiting/shaping rules for
> + specific cgroup(s).
> +
> + Say N if unsure.
> +
> config CPUSETS
> bool "Cpuset support"
> depends on SMP && CGROUPS
> diff -urpN linux-2.6.24-rc8/kernel/cgroup_netlimit.c linux-2.6.24-rc8-cgroup-netlimit/kernel/cgroup_netlimit.c
> --- linux-2.6.24-rc8/kernel/cgroup_netlimit.c 1970-01-01 01:00:00.000000000 +0100
> +++ linux-2.6.24-rc8-cgroup-netlimit/kernel/cgroup_netlimit.c 2008-01-22 21:35:53.000000000 +0100
> @@ -0,0 +1,229 @@
> +/*
> + * 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 <a.righi@cineca.it>
> + */
> +
> +#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/fs.h>
> +#include <linux/jiffies.h>
> +#include <linux/spinlock.h>
> +#include <linux/cgroup_netlimit.h>
> +
> +struct netlimit {
> + struct cgroup_subsys_state css;
> + spinlock_t lock[CGROUP_NETLIMIT_END];
> + unsigned long bandwidth[CGROUP_NETLIMIT_END];
> + unsigned long req[CGROUP_NETLIMIT_END];
> + unsigned long last_request[CGROUP_NETLIMIT_END];
> +};
> +
> +static inline struct netlimit *cgroup_to_netlimit(struct cgroup *cont)
> +{
> + return container_of(cgroup_subsys_state(cont, netlimit_subsys_id),
> + struct netlimit, css);
> +}
> +
> +static inline struct netlimit *task_to_netlimit(struct task_struct *task)
> +{
> + return container_of(task_subsys_state(task, netlimit_subsys_id),
> + struct netlimit, css);
> +}
> +
> +/*
> + * Rules: you can only create a cgroup if:
> + * 1. you are capable(CAP_SYS_ADMIN)
> + * 2. the target cgroup is a descendant of your own cgroup
> + *
> + * Note: called from kernel/cgroup.c with cgroup_lock() held.
> + */
> +static struct cgroup_subsys_state *netlimit_create(
> + struct cgroup_subsys *ss, struct cgroup *cont)
> +{
> + struct netlimit *nl;
> + int i;
> +
> + if (!capable(CAP_SYS_ADMIN))
> + return ERR_PTR(-EPERM);
> +
> + if (!cgroup_is_descendant(cont))
> + return ERR_PTR(-EPERM);
> +
> + nl = kzalloc(sizeof(struct netlimit), GFP_KERNEL);
> + if (unlikely(!nl))
> + return ERR_PTR(-ENOMEM);
> +
> + for (i = 0; i < CGROUP_NETLIMIT_END; i++) {
> + spin_lock_init(&nl->lock[i]);
> + nl->last_request[i] = jiffies;
> + }
> +
> + return &nl->css;
> +}
> +
> +/*
> + * Note: called from kernel/cgroup.c with cgroup_lock() held.
> + */
> +static void netlimit_destroy(struct cgroup_subsys *ss, struct cgroup *cont)
> +{
> + kfree(cgroup_to_netlimit(cont));
> +}
> +
> +static ssize_t netlimit_read(struct cgroup *cont, struct cftype *cft,
> + struct file *file, char __user *buf,
> + size_t nbytes, loff_t *ppos)
> +{
> + ssize_t count, ret;
> + unsigned long delta, bandwidth, req, last_request;
> + struct netlimit *nl;
> + char *page;
> +
> + page = (char *)__get_free_page(GFP_TEMPORARY);
> + if (!page)
> + return -ENOMEM;
> +
> + cgroup_lock();
> + if (cgroup_is_removed(cont)) {
> + cgroup_unlock();
> + ret = -ENODEV;
> + goto out;
> + }
> +
> + nl = cgroup_to_netlimit(cont);
> + spin_lock_irq(&nl->lock[cft->private]);
> +
> + delta = (long)jiffies - (long)nl->last_request[cft->private];
> + bandwidth = nl->bandwidth[cft->private];
> + req = nl->req[cft->private];
> + last_request = nl->last_request[cft->private];
> +
> + spin_unlock_irq(&nl->lock[cft->private]);
> + cgroup_unlock();
> +
> + /* print additional debugging stuff */
> + count = sprintf(page, " type: %s\n"
> + "max-bandwidth: %lu KB/sec\n"
> + " requested: %lu KB\n"
> + " last request: %lu jiffies\n"
> + " delta: %lu jiffies\n",
> + cft->name,
> + bandwidth, req >> 10, last_request, delta);
> +
> + ret = simple_read_from_buffer(buf, nbytes, ppos, page, count);
> +
> +out:
> + free_page((unsigned long)page);
> + return ret;
> +}
> +
> +static int netlimit_write_uint(struct cgroup *cont, struct cftype *cft,
> + u64 val)
> +{
> + struct netlimit *nl;
> + int ret = 0;
> +
> + cgroup_lock();
> + if (cgroup_is_removed(cont)) {
> + ret = -ENODEV;
> + goto out;
> + }
> +
> + nl = cgroup_to_netlimit(cont);
> +
> + spin_lock_irq(&nl->lock[cft->private]);
> + nl->bandwidth[cft->private] = (unsigned long)val;
> + nl->req[cft->private] = 0;
> + nl->last_request[cft->private] = jiffies;
> + spin_unlock_irq(&nl->lock[cft->private]);
> +
> +out:
> + cgroup_unlock();
> + return ret;
> +}
> +
> +static struct cftype files[] = {
> + CGROUP_NETLIMIT_FILE("tot", CGROUP_NETLIMIT_TOT),
> + CGROUP_NETLIMIT_FILE("tcp", CGROUP_NETLIMIT_TCP),
> + CGROUP_NETLIMIT_FILE("udp", CGROUP_NETLIMIT_UDP),
> + CGROUP_NETLIMIT_FILE("raw", CGROUP_NETLIMIT_RAW),
> +};
> +
> +static int netlimit_populate(struct cgroup_subsys *ss, struct cgroup *cont)
> +{
> + return cgroup_add_files(cont, ss, files, ARRAY_SIZE(files));
> +}
> +
> +struct cgroup_subsys netlimit_subsys = {
> + .name = "net",
> + .create = netlimit_create,
> + .destroy = netlimit_destroy,
> + .populate = netlimit_populate,
> + .subsys_id = netlimit_subsys_id,
> +};
> +
> +void cgroup_nl_acct(int limit_id, size_t bytes)
> +{
> + struct netlimit *nl;
> +
> + nl = task_to_netlimit(current);
> + if (!nl || !nl->bandwidth[limit_id])
> + return;
> +
> + nl->req[limit_id] += bytes;
> +}
> +EXPORT_SYMBOL(cgroup_nl_acct);
> +
> +void cgroup_nl_throttle(int limit_id, int interruptible)
> +{
> + struct netlimit *nl;
> + unsigned long delta, t;
> + long sleep;
> +
> + nl = task_to_netlimit(current);
> + if (!nl || !nl->bandwidth[limit_id])
> + return;
> +
> + delta = (long)jiffies - (long)nl->last_request[limit_id];
> + if (!delta)
> + return;
> +
> + t = msecs_to_jiffies(nl->req[limit_id] / nl->bandwidth[limit_id]);
> + if (!t)
> + return;
> +
> + sleep = t - delta;
> + if (sleep > 0) {
> + pr_debug("cgroup-netlimit(%s):"
> + " task %p (%s) must sleep %lu jiffies\n",
> + files[limit_id].name,
> + current, current->comm, sleep);
> + if (interruptible)
> + schedule_timeout_interruptible(sleep);
> + else
> + schedule_timeout_uninterruptible(sleep);
> + return;
> + }
> +
> + nl->req[limit_id] = 0;
> + nl->last_request[limit_id] = jiffies;
> +}
> +EXPORT_SYMBOL(cgroup_nl_throttle);
> diff -urpN linux-2.6.24-rc8/kernel/Makefile linux-2.6.24-rc8-cgroup-netlimit/kernel/Makefile
> --- linux-2.6.24-rc8/kernel/Makefile 2008-01-16 05:22:48.000000000 +0100
> +++ linux-2.6.24-rc8-cgroup-netlimit/kernel/Makefile 2008-01-22 11:39:23.000000000 +0100
> @@ -41,6 +41,7 @@ obj-$(CONFIG_CGROUPS) += cgroup.o
> obj-$(CONFIG_CGROUP_DEBUG) += cgroup_debug.o
> obj-$(CONFIG_CPUSETS) += cpuset.o
> obj-$(CONFIG_CGROUP_NS) += ns_cgroup.o
> +obj-$(CONFIG_CGROUP_NETLIMIT) += cgroup_netlimit.o
> obj-$(CONFIG_IKCONFIG) += configs.o
> obj-$(CONFIG_STOP_MACHINE) += stop_machine.o
> obj-$(CONFIG_AUDIT) += audit.o auditfilter.o
> diff -urpN linux-2.6.24-rc8/net/socket.c linux-2.6.24-rc8-cgroup-netlimit/net/socket.c
> --- linux-2.6.24-rc8/net/socket.c 2008-01-16 05:22:48.000000000 +0100
> +++ linux-2.6.24-rc8-cgroup-netlimit/net/socket.c 2008-01-22 21:33:46.000000000 +0100
> @@ -85,6 +85,7 @@
> #include <linux/audit.h>
> #include <linux/wireless.h>
> #include <linux/nsproxy.h>
> +#include <linux/cgroup_netlimit.h>
>
> #include <asm/uaccess.h>
> #include <asm/unistd.h>
> @@ -551,10 +552,33 @@ static inline int __sock_sendmsg(struct
> si->size = size;
>
> err = security_socket_sendmsg(sock, msg, size);
> - if (err)
> - return err;
> + if (!err)
> + err = sock->ops->sendmsg(iocb, sock, msg, size);
>
> - return sock->ops->sendmsg(iocb, sock, msg, size);
> + if (err >= 0 && sock->sk) {
> + switch (sock->sk->sk_family) {
> + case PF_INET:
> + case PF_INET6:
> + switch (sock->sk->sk_type) {
> + case SOCK_STREAM:
> + cgroup_nl_acct(CGROUP_NETLIMIT_TCP, size);
> + cgroup_nl_throttle(CGROUP_NETLIMIT_TCP, 1);
> + break;
> + case SOCK_DGRAM:
> + cgroup_nl_acct(CGROUP_NETLIMIT_UDP, size);
> + cgroup_nl_throttle(CGROUP_NETLIMIT_UDP, 1);
> + break;
> + case SOCK_RAW:
> + cgroup_nl_acct(CGROUP_NETLIMIT_RAW, size);
> + cgroup_nl_throttle(CGROUP_NETLIMIT_RAW, 1);
> + break;
> + }
> + cgroup_nl_acct(CGROUP_NETLIMIT_TOT, size);
> + cgroup_nl_throttle(CGROUP_NETLIMIT_TOT, 1);
> + }
> + }
> +
> + return err;
> }
>
> int sock_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
> @@ -633,10 +657,33 @@ static inline int __sock_recvmsg(struct
> si->flags = flags;
>
> err = security_socket_recvmsg(sock, msg, size, flags);
> - if (err)
> - return err;
> + if (!err)
> + err = sock->ops->recvmsg(iocb, sock, msg, size, flags);
>
> - return sock->ops->recvmsg(iocb, sock, msg, size, flags);
> + if (err >= 0 && sock->sk) {
> + switch (sock->sk->sk_family) {
> + case PF_INET:
> + case PF_INET6:
> + switch (sock->sk->sk_type) {
> + case SOCK_STREAM:
> + cgroup_nl_acct(CGROUP_NETLIMIT_TCP, size);
> + cgroup_nl_throttle(CGROUP_NETLIMIT_TCP, 1);
> + break;
> + case SOCK_DGRAM:
> + cgroup_nl_acct(CGROUP_NETLIMIT_UDP, size);
> + cgroup_nl_throttle(CGROUP_NETLIMIT_UDP, 1);
> + break;
> + case SOCK_RAW:
> + cgroup_nl_acct(CGROUP_NETLIMIT_RAW, size);
> + cgroup_nl_throttle(CGROUP_NETLIMIT_RAW, 1);
> + break;
> + }
> + cgroup_nl_acct(CGROUP_NETLIMIT_TOT, size);
> + cgroup_nl_throttle(CGROUP_NETLIMIT_TOT, 1);
> + }
> + }
> +
> + return err;
> }
>
> int sock_recvmsg(struct socket *sock, struct msghdr *msg,
>


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