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Subject[PATCH 2/7] Porting io-throttle v11 to 2.6.28-rc2-mm1
From: Andrea Righi <righi.andrea@gmail.com>

Porting io-throttle v11 to 2.6.28-rc2-mm1

Signed-off-by: Andrea Righi <righi.andrea@gmail.com>
---
Documentation/controllers/io-throttle.txt | 409 ++++++++++++++++
block/Makefile | 2 +
block/blk-core.c | 4 +
block/blk-io-throttle.c | 735 +++++++++++++++++++++++++++++
fs/aio.c | 12 +
fs/direct-io.c | 3 +
fs/proc/base.c | 18 +
include/linux/blk-io-throttle.h | 95 ++++
include/linux/cgroup_subsys.h | 6 +
include/linux/memcontrol.h | 5 +-
include/linux/res_counter.h | 69 ++-
include/linux/sched.h | 7 +
init/Kconfig | 10 +
kernel/fork.c | 8 +
kernel/res_counter.c | 73 +++-
mm/memcontrol.c | 30 ++
mm/page-writeback.c | 4 +
mm/readahead.c | 3 +
18 files changed, 1474 insertions(+), 19 deletions(-)
create mode 100644 Documentation/controllers/io-throttle.txt
create mode 100644 block/blk-io-throttle.c
create mode 100644 include/linux/blk-io-throttle.h

diff --git a/Documentation/controllers/io-throttle.txt b/Documentation/controllers/io-throttle.txt
new file mode 100644
index 0000000..2a3bbd1
--- /dev/null
+++ b/Documentation/controllers/io-throttle.txt
@@ -0,0 +1,409 @@
+
+ Block device I/O bandwidth controller
+
+----------------------------------------------------------------------
+1. DESCRIPTION
+
+This controller allows to limit the I/O bandwidth of specific block devices for
+specific process containers (cgroups [1]) imposing additional delays on I/O
+requests for those processes that exceed the limits defined in the control
+group filesystem.
+
+Bandwidth limiting rules offer better control over QoS with respect to priority
+or weight-based solutions that only give information about applications'
+relative performance requirements. Nevertheless, priority based solutions are
+affected by performance bursts, when only low-priority requests are submitted
+to a general purpose resource dispatcher.
+
+The goal of the I/O bandwidth controller is to improve performance
+predictability from the applications' point of view and provide performance
+isolation of different control groups sharing the same block devices.
+
+NOTE #1: If you're looking for a way to improve the overall throughput of the
+system probably you should use a different solution.
+
+NOTE #2: The current implementation does not guarantee minimum bandwidth
+levels, the QoS is implemented only slowing down I/O "traffic" that exceeds the
+limits specified by the user; minimum I/O rate thresholds are supposed to be
+guaranteed if the user configures a proper I/O bandwidth partitioning of the
+block devices shared among the different cgroups (theoretically if the sum of
+all the single limits defined for a block device doesn't exceed the total I/O
+bandwidth of that device).
+
+----------------------------------------------------------------------
+2. USER INTERFACE
+
+A new I/O limitation rule is described using the files:
+- blockio.bandwidth-max
+- blockio.iops-max
+
+The I/O bandwidth (blockio.bandwidth-max) can be used to limit the throughput
+of a certain cgroup, while blockio.iops-max can be used to throttle cgroups
+containing applications doing a sparse/seeky I/O workload. Any combination of
+them can be used to define more complex I/O limiting rules, expressed both in
+terms of iops/s and bandwidth.
+
+The same files can be used to set multiple rules for different block devices
+relative to the same cgroup.
+
+The following syntax can be used to configure any limiting rule:
+
+# /bin/echo DEV:LIMIT:STRATEGY:BUCKET_SIZE > CGROUP/FILE
+
+- DEV is the name of the device the limiting rule is applied to.
+
+- LIMIT is the maximum I/O activity allowed on DEV by CGROUP; LIMIT can
+ represent a bandwidth limitation (expressed in bytes/s) when writing to
+ blockio.bandwidth-max, or a limitation to the maximum I/O operations per
+ second (expressed in iops/s) issued by CGROUP.
+
+ A generic I/O limiting rule for a block device DEV can be removed setting the
+ LIMIT to 0.
+
+- STRATEGY is the throttling strategy used to throttle the applications' I/O
+ requests from/to device DEV. At the moment two different strategies can be
+ used [2][3]:
+
+ 0 = leaky bucket: the controller accepts at most B bytes (B = LIMIT * time)
+ or O operations (O = LIMIT * time); further I/O requests
+ are delayed scheduling a timeout for the tasks that made
+ those requests.
+
+ Different I/O flow
+ | | |
+ | v |
+ | v
+ v
+ .......
+ \ /
+ \ / leaky-bucket
+ ---
+ |||
+ vvv
+ Smoothed I/O flow
+
+ 1 = token bucket: LIMIT tokens are added to the bucket every seconds; the
+ bucket can hold at the most BUCKET_SIZE tokens; I/O
+ requests are accepted if there are available tokens in the
+ bucket; when a request of N bytes arrives N tokens are
+ removed from the bucket; if fewer than N tokens are
+ available the request is delayed until a sufficient amount
+ of token is available in the bucket.
+
+ Tokens (I/O rate)
+ o
+ o
+ o
+ ....... <--.
+ \ / | Bucket size (burst limit)
+ \ooo/ |
+ --- <--'
+ |ooo
+ Incoming --->|---> Conforming
+ I/O |oo I/O
+ requests -->|--> requests
+ |
+ ---->|
+
+ Leaky bucket is more precise than token bucket to respect the limits, because
+ bursty workloads are always smoothed. Token bucket, instead, allows a small
+ irregularity degree in the I/O flows (burst limit), and, for this, it is
+ better in terms of efficiency (bursty workloads are not smoothed when there
+ are sufficient tokens in the bucket).
+
+- BUCKET_SIZE is used only with token bucket (STRATEGY == 1) and defines the
+ size of the bucket in bytes (blockio.bandwidth-max) or in I/O operations
+ (blockio.iops-max).
+
+- CGROUP is the name of the limited process container.
+
+Also the following syntaxes are allowed:
+
+- remove an I/O bandwidth limiting rule
+# /bin/echo DEV:0 > CGROUP/blockio.bandwidth-max
+
+- configure a limiting rule using leaky bucket throttling (ignore bucket size):
+# /bin/echo DEV:LIMIT:0 > CGROUP/blockio.bandwidth-max
+
+- configure a limiting rule using token bucket throttling
+ (with bucket size == LIMIT):
+# /bin/echo DEV:LIMIT:1 > CGROUP/blockio.bandwidth-max
+
+2.2. Show I/O limiting rules
+
+All the defined rules and statistics for a specific cgroup can be shown reading
+the files blockio.bandwidth-max for bandwidth constraints and blockio.iops-max
+for I/O operations per second constraints.
+
+The following syntax is used:
+
+$ cat CGROUP/blockio.bandwidth-max
+MAJOR MINOR LIMIT STRATEGY LEAKY_STAT BUCKET_SIZE BUCKET_FILL TIME_DELTA
+
+- MAJOR is the major device number of DEV (defined above)
+
+- MINOR is the minor device number of DEV (defined above)
+
+- LIMIT, STRATEGY and BUCKET_SIZE are the same parameters defined above
+
+- LEAKY_STAT is the amount of bytes (blockio.bandwidth-max) or I/O operations
+ (blockio.iops-max) currently allowed by the I/O controller (only used with
+ leaky bucket strategy - STRATEGY == 0)
+
+- BUCKET_FILL represents the amount of tokens present in the bucket (only used
+ with token bucket strategy - STRATEGY == 1)
+
+- TIME_DELTA can be one of the following:
+ - the amount of jiffies elapsed from the last I/O request (token bucket)
+ - the amount of jiffies during which the bytes or the number of I/O
+ operations given by LEAKY_STAT have been accumulated (leaky bucket)
+
+Multiple per-block device rules are reported in multiple rows
+(DEVi, i = 1 .. n):
+
+$ cat CGROUP/blockio.bandwidth-max
+MAJOR1 MINOR1 BW1 STRATEGY1 LEAKY_STAT1 BUCKET_SIZE1 BUCKET_FILL1 TIME_DELTA1
+MAJOR1 MINOR1 BW2 STRATEGY2 LEAKY_STAT2 BUCKET_SIZE2 BUCKET_FILL2 TIME_DELTA2
+...
+MAJORn MINORn BWn STRATEGYn LEAKY_STATn BUCKET_SIZEn BUCKET_FILLn TIME_DELTAn
+
+The same fields are used to describe I/O operations/sec rules. The only
+difference is that the cost of each I/O operation is scaled up by a factor of
+1000. This allows to apply better fine grained sleeps and provide a more
+precise throttling.
+
+$ cat CGROUP/blockio.iops-max
+MAJOR MINOR LIMITx1000 STRATEGY LEAKY_STATx1000 BUCKET_SIZEx1000 BUCKET_FILLx1000 TIME_DELTA
+...
+
+2.3. Additional I/O statistics
+
+Additional cgroup I/O throttling statistics are reported in
+blockio.throttlecnt:
+
+$ cat CGROUP/blockio.throttlecnt
+MAJOR MINOR BW_COUNTER BW_SLEEP IOPS_COUNTER IOPS_SLEEP
+
+ - MAJOR, MINOR are respectively the major and the minor number of the device
+ the following statistics refer to
+ - BW_COUNTER gives the number of times that the cgroup bandwidth limit of
+ this particular device was exceeded
+ - BW_SLEEP is the amount of sleep time measured in clock ticks (divide
+ by sysconf(_SC_CLK_TCK)) imposed to the processes of this cgroup that
+ exceeded the bandwidth limit for this particular device
+ - IOPS_COUNTER gives the number of times that the cgroup I/O operation per
+ second limit of this particular device was exceeded
+ - IOPS_SLEEP is the amount of sleep time measured in clock ticks (divide
+ by sysconf(_SC_CLK_TCK)) imposed to the processes of this cgroup that
+ exceeded the I/O operations per second limit for this particular device
+
+Example:
+$ cat CGROUP/blockio.throttlecnt
+8 0 0 0 0 0
+^ ^ ^ ^ ^ ^
+ \ \ \ \ \ \___iops sleep (in clock ticks)
+ \ \ \ \ \____iops throttle counter
+ \ \ \ \_____bandwidth sleep (in clock ticks)
+ \ \ \______bandwidth throttle counter
+ \ \_______minor dev. number
+ \________major dev. number
+
+Distinct statistics for each process are reported in
+/proc/PID/io-throttle-stat:
+
+$ cat /proc/PID/io-throttle-stat
+BW_COUNTER BW_SLEEP IOPS_COUNTER IOPS_SLEEP
+
+Example:
+$ cat /proc/$$/io-throttle-stat
+0 0 0 0
+^ ^ ^ ^
+ \ \ \ \_____global iops sleep (in clock ticks)
+ \ \ \______global iops counter
+ \ \_______global bandwidth sleep (clock ticks)
+ \________global bandwidth counter
+
+2.4. Examples
+
+* Mount the cgroup filesystem (blockio subsystem):
+ # mkdir /mnt/cgroup
+ # mount -t cgroup -oblockio blockio /mnt/cgroup
+
+* Instantiate the new cgroup "foo":
+ # mkdir /mnt/cgroup/foo
+ --> the cgroup foo has been created
+
+* Add the current shell process to the cgroup "foo":
+ # /bin/echo $$ > /mnt/cgroup/foo/tasks
+ --> the current shell has been added to the cgroup "foo"
+
+* Give maximum 1MiB/s of I/O bandwidth on /dev/sda for the cgroup "foo", using
+ leaky bucket throttling strategy:
+ # /bin/echo /dev/sda:$((1024 * 1024)):0:0 > \
+ > /mnt/cgroup/foo/blockio.bandwidth-max
+ # sh
+ --> the subshell 'sh' is running in cgroup "foo" and it can use a maximum I/O
+ bandwidth of 1MiB/s on /dev/sda
+
+* Give maximum 8MiB/s of I/O bandwidth on /dev/sdb for the cgroup "foo", using
+ token bucket throttling strategy, bucket size = 8MiB:
+ # /bin/echo /dev/sdb:$((8 * 1024 * 1024)):1:$((8 * 1024 * 1024)) > \
+ > /mnt/cgroup/foo/blockio.bandwidth-max
+ # sh
+ --> the subshell 'sh' is running in cgroup "foo" and it can use a maximum I/O
+ bandwidth of 1MiB/s on /dev/sda (controlled by leaky bucket throttling)
+ and 8MiB/s on /dev/sdb (controlled by token bucket throttling)
+
+* Run a benchmark doing I/O on /dev/sda and /dev/sdb; I/O limits and usage
+ defined for cgroup "foo" can be shown as following:
+ # cat /mnt/cgroup/foo/blockio.bandwidth-max
+ 8 16 8388608 1 0 8388608 -522560 48
+ 8 0 1048576 0 737280 0 0 216
+
+* Extend the maximum I/O bandwidth for the cgroup "foo" to 16MiB/s on /dev/sda:
+ # /bin/echo /dev/sda:$((16 * 1024 * 1024)):0:0 > \
+ > /mnt/cgroup/foo/blockio.bandwidth-max
+ # cat /mnt/cgroup/foo/blockio.bandwidth-max
+ 8 16 8388608 1 0 8388608 -84432 206436
+ 8 0 16777216 0 0 0 0 15212
+
+* Remove limiting rule on /dev/sdb for cgroup "foo":
+ # /bin/echo /dev/sdb:0:0:0 > /mnt/cgroup/foo/blockio.bandwidth-max
+ # cat /mnt/cgroup/foo/blockio.bandwidth-max
+ 8 0 16777216 0 0 0 0 110388
+
+* Set a maximum of 100 I/O operations/sec (leaky bucket strategy) to /dev/sdc
+ for cgroup "foo":
+ # /bin/echo /dev/sdc:100:0 > /mnt/cgroup/foo/blockio.iops-max
+ # cat /mnt/cgroup/foo/blockio.iops-max
+ 8 32 100000 0 846000 0 2113
+ ^ ^
+ /________/
+ /
+ Remember: these values are scaled up by a factor of 1000 to apply a fine
+ grained throttling (i.e. LIMIT == 100000 means a maximum of 100 I/O operation
+ per second)
+
+* Remove limiting rule for I/O operations from /dev/sdc for cgroup "foo":
+ # /bin/echo /dev/sdc:0 > /mnt/cgroup/foo/blockio.iops-max
+
+----------------------------------------------------------------------
+3. ADVANTAGES OF PROVIDING THIS FEATURE
+
+* Allow I/O traffic shaping for block device shared among different cgroups
+* Improve I/O performance predictability on block devices shared between
+ different cgroups
+* Limiting rules do not depend of the particular I/O scheduler (anticipatory,
+ deadline, CFQ, noop) and/or the type of the underlying block devices
+* The bandwidth limitations are guaranteed both for synchronous and
+ asynchronous operations, even the I/O passing through the page cache or
+ buffers and not only direct I/O (see below for details)
+* It is possible to implement a simple user-space application to dynamically
+ adjust the I/O workload of different process containers at run-time,
+ according to the particular users' requirements and applications' performance
+ constraints
+
+----------------------------------------------------------------------
+4. DESIGN
+
+The I/O throttling is performed imposing an explicit timeout, via
+schedule_timeout_killable() on the processes that exceed the I/O limits
+dedicated to the cgroup they belong to. I/O accounting happens per cgroup.
+
+It just works as expected for read operations: the real I/O activity is reduced
+synchronously according to the defined limitations.
+
+Multiple re-reads of pages already present in the page cache are not considered
+to account the I/O activity, since they actually don't generate any real I/O
+operation.
+
+This means that a process that re-reads multiple times the same blocks of a
+file is affected by the I/O limitations only for the actual I/O performed from
+the underlying block devices.
+
+For write operations the scenario is a bit more complex, because the writes in
+the page cache are processed asynchronously by kernel threads (pdflush), using
+a write-back policy. So the real writes to the underlying block devices occur
+in a different I/O context respect to the task that originally generated the
+dirty pages.
+
+The I/O bandwidth controller uses the following solution to resolve this
+problem.
+
+The cost of each I/O operation is always accounted when the operation is
+submitted to the I/O subsystem (submit_bio()).
+
+If the operation is a read then we automatically know that the context of the
+request is the current task and so we can charge the cgroup the current task
+belongs to. And throttle the current task as well, if it exceeded the cgroup
+limitations.
+
+If the operation is a write, we can charge the right cgroup looking at the
+owner of the first page involved in the I/O operation, that gives the context
+that generated the I/O activity at the source. This information can be
+retrieved using the page_cgroup functionality provided by the cgroup memory
+controller [4]. In this way we can correctly account the I/O cost to the right
+cgroup, but we cannot throttle the current task in this stage, because, in
+general, it is a different task (e.g. a kernel thread that is processing
+asynchronously the dirty page). For this reason, throttling of write operations
+is always performed asynchronously in balance_dirty_pages_ratelimited_nr(), a
+function always called by processes which are dirtying memory.
+
+Multiple rules for different block devices are stored in a linked list, using
+the dev_t number of each block device as key to uniquely identify each element
+of the list. RCU synchronization is used to protect the whole list structure,
+since the elements in the list are not supposed to change frequently (they
+change only when a new rule is defined or an old rule is removed or updated),
+while the reads in the list occur at each operation that generates I/O. This
+allows to provide zero overhead for cgroups that do not use any limitation.
+
+WARNING: per-block device limiting rules always refer to the dev_t device
+number. If a block device is unplugged (i.e. a USB device) the limiting rules
+defined for that device persist and they are still valid if a new device is
+plugged in the system and it uses the same major and minor numbers.
+
+NOTE: explicit sleeps are *not* imposed on tasks doing asynchronous I/O (AIO)
+operations; AIO throttling is performed returning -EAGAIN from sys_io_submit().
+Userspace applications must be able to handle this error code opportunely.
+
+----------------------------------------------------------------------
+5. TODO
+
+* Implement a rbtree per request queue; all the requests queued to the I/O
+ subsystem first will go in this rbtree. Then based on cgroup grouping and
+ control policy dispatch the requests and pass them to the elevator associated
+ with the queue. This would allow to provide both bandwidth limiting and
+ proportional bandwidth functionalities using a generic approach (suggested by
+ Vivek Goyal)
+
+* Improve fair throttling: distribute the time to sleep among all the tasks of
+ a cgroup that exceeded the I/O limits, depending of the amount of IO activity
+ previously generated in the past by each task (see task_io_accounting)
+
+* Try to reduce the cost of calling cgroup_io_throttle() on every submit_bio();
+ this is not too much expensive, but the call of task_subsys_state() has
+ surely a cost. A possible solution could be to temporarily account I/O in the
+ current task_struct and call cgroup_io_throttle() only on each X MB of I/O.
+ Or on each Y number of I/O requests as well. Better if both X and/or Y can be
+ tuned at runtime by a userspace tool
+
+* Think an alternative design for general purpose usage; special purpose usage
+ right now is restricted to improve I/O performance predictability and
+ evaluate more precise response timings for applications doing I/O. To a large
+ degree the block I/O bandwidth controller should implement a more complex
+ logic to better evaluate real I/O operations cost, depending also on the
+ particular block device profile (i.e. USB stick, optical drive, hard disk,
+ etc.). This would also allow to appropriately account I/O cost for seeky
+ workloads, respect to large stream workloads. Instead of looking at the
+ request stream and try to predict how expensive the I/O cost will be, a
+ totally different approach could be to collect request timings (start time /
+ elapsed time) and based on collected informations, try to estimate the I/O
+ cost and usage
+
+----------------------------------------------------------------------
+6. REFERENCES
+
+[1] Documentation/cgroups/cgroups.txt
+[2] http://en.wikipedia.org/wiki/Leaky_bucket
+[3] http://en.wikipedia.org/wiki/Token_bucket
+[4] Documentation/controllers/memory.txt
diff --git a/block/Makefile b/block/Makefile
index bfe7304..6049d09 100644
--- a/block/Makefile
+++ b/block/Makefile
@@ -13,6 +13,8 @@ obj-$(CONFIG_IOSCHED_AS) += as-iosched.o
obj-$(CONFIG_IOSCHED_DEADLINE) += deadline-iosched.o
obj-$(CONFIG_IOSCHED_CFQ) += cfq-iosched.o

+obj-$(CONFIG_CGROUP_IO_THROTTLE) += blk-io-throttle.o
+
obj-$(CONFIG_BLK_DEV_IO_TRACE) += blktrace.o
obj-$(CONFIG_BLOCK_COMPAT) += compat_ioctl.o
obj-$(CONFIG_BLK_DEV_INTEGRITY) += blk-integrity.o
diff --git a/block/blk-core.c b/block/blk-core.c
index c3df30c..e187476 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -26,6 +26,7 @@
#include <linux/swap.h>
#include <linux/writeback.h>
#include <linux/task_io_accounting_ops.h>
+#include <linux/blk-io-throttle.h>
#include <linux/blktrace_api.h>
#include <linux/fault-inject.h>

@@ -1536,9 +1537,12 @@ void submit_bio(int rw, struct bio *bio)
if (bio_has_data(bio)) {
if (rw & WRITE) {
count_vm_events(PGPGOUT, count);
+ cgroup_io_throttle(bio_iovec_idx(bio, 0)->bv_page,
+ bio->bi_bdev, bio->bi_size, 0);
} else {
task_io_account_read(bio->bi_size);
count_vm_events(PGPGIN, count);
+ cgroup_io_throttle(NULL, bio->bi_bdev, bio->bi_size, 1);
}

if (unlikely(block_dump)) {
diff --git a/block/blk-io-throttle.c b/block/blk-io-throttle.c
new file mode 100644
index 0000000..bb27587
--- /dev/null
+++ b/block/blk-io-throttle.c
@@ -0,0 +1,735 @@
+/*
+ * 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@gmail.com>
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/res_counter.h>
+#include <linux/memcontrol.h>
+#include <linux/slab.h>
+#include <linux/gfp.h>
+#include <linux/err.h>
+#include <linux/genhd.h>
+#include <linux/hardirq.h>
+#include <linux/list.h>
+#include <linux/seq_file.h>
+#include <linux/spinlock.h>
+#include <linux/blk-io-throttle.h>
+
+/*
+ * Statistics for I/O bandwidth controller.
+ */
+enum iothrottle_stat_index {
+ /* # of times the cgroup has been throttled for bw limit */
+ IOTHROTTLE_STAT_BW_COUNT,
+ /* # of jiffies spent to sleep for throttling for bw limit */
+ IOTHROTTLE_STAT_BW_SLEEP,
+ /* # of times the cgroup has been throttled for iops limit */
+ IOTHROTTLE_STAT_IOPS_COUNT,
+ /* # of jiffies spent to sleep for throttling for iops limit */
+ IOTHROTTLE_STAT_IOPS_SLEEP,
+ /* total number of bytes read and written */
+ IOTHROTTLE_STAT_BYTES_TOT,
+ /* total number of I/O operations */
+ IOTHROTTLE_STAT_IOPS_TOT,
+
+ IOTHROTTLE_STAT_NSTATS,
+};
+
+struct iothrottle_stat_cpu {
+ unsigned long long count[IOTHROTTLE_STAT_NSTATS];
+} ____cacheline_aligned_in_smp;
+
+struct iothrottle_stat {
+ struct iothrottle_stat_cpu cpustat[NR_CPUS];
+};
+
+static void iothrottle_stat_add(struct iothrottle_stat *stat,
+ enum iothrottle_stat_index type, unsigned long long val)
+{
+ int cpu = get_cpu();
+
+ stat->cpustat[cpu].count[type] += val;
+ put_cpu();
+}
+
+static void iothrottle_stat_add_sleep(struct iothrottle_stat *stat,
+ int type, unsigned long long sleep)
+{
+ int cpu = get_cpu();
+
+ switch (type) {
+ case IOTHROTTLE_BANDWIDTH:
+ stat->cpustat[cpu].count[IOTHROTTLE_STAT_BW_COUNT]++;
+ stat->cpustat[cpu].count[IOTHROTTLE_STAT_BW_SLEEP] += sleep;
+ break;
+ case IOTHROTTLE_IOPS:
+ stat->cpustat[cpu].count[IOTHROTTLE_STAT_IOPS_COUNT]++;
+ stat->cpustat[cpu].count[IOTHROTTLE_STAT_IOPS_SLEEP] += sleep;
+ break;
+ }
+ put_cpu();
+}
+
+static unsigned long long iothrottle_read_stat(struct iothrottle_stat *stat,
+ enum iothrottle_stat_index idx)
+{
+ int cpu;
+ unsigned long long ret = 0;
+
+ for_each_possible_cpu(cpu)
+ ret += stat->cpustat[cpu].count[idx];
+ return ret;
+}
+
+struct iothrottle_sleep {
+ unsigned long long bw_sleep;
+ unsigned long long iops_sleep;
+};
+
+/*
+ * 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
+ * @bw: max i/o bandwidth (in bytes/s)
+ * @iops: max i/o operations per second
+ * @stat: throttling statistics
+ *
+ * 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;
+ struct res_counter bw;
+ struct res_counter iops;
+ struct iothrottle_stat stat;
+};
+
+/**
+ * struct iothrottle - throttling rules for a cgroup
+ * @css: pointer to the cgroup state
+ * @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:
+ * - hold cgroup_lock() for update.
+ * - hold rcu_read_lock() for read.
+ */
+struct iothrottle {
+ struct cgroup_subsys_state css;
+ struct list_head list;
+};
+static struct iothrottle init_iothrottle;
+
+static inline struct iothrottle *cgroup_to_iothrottle(struct cgroup *cgrp)
+{
+ return container_of(cgroup_subsys_state(cgrp, iothrottle_subsys_id),
+ struct iothrottle, css);
+}
+
+/*
+ * Note: called with rcu_read_lock() held.
+ */
+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() or iot->lock held.
+ */
+static struct iothrottle_node *
+iothrottle_search_node(const struct iothrottle *iot, dev_t dev)
+{
+ struct iothrottle_node *n;
+
+ if (list_empty(&iot->list))
+ return NULL;
+ 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 void
+iothrottle_replace_node(struct iothrottle *iot, struct iothrottle_node *old,
+ struct iothrottle_node *new)
+{
+ list_replace_rcu(&old->node, &new->node);
+}
+
+/*
+ * Note: called with iot->lock held.
+ */
+static inline void
+iothrottle_delete_node(struct iothrottle *iot, struct iothrottle_node *n)
+{
+ list_del_rcu(&n->node);
+}
+
+/*
+ * Note: called from kernel/cgroup.c with cgroup_lock() held.
+ */
+static struct cgroup_subsys_state *
+iothrottle_create(struct cgroup_subsys *ss, struct cgroup *cgrp)
+{
+ struct iothrottle *iot;
+
+ if (unlikely((cgrp->parent) == NULL))
+ iot = &init_iothrottle;
+ else {
+ iot = kmalloc(sizeof(*iot), GFP_KERNEL);
+ if (unlikely(!iot))
+ return ERR_PTR(-ENOMEM);
+ }
+ INIT_LIST_HEAD(&iot->list);
+
+ return &iot->css;
+}
+
+/*
+ * Note: called from kernel/cgroup.c with cgroup_lock() held.
+ */
+static void iothrottle_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
+{
+ struct iothrottle_node *n, *p;
+ struct iothrottle *iot = cgroup_to_iothrottle(cgrp);
+
+ /*
+ * don't worry about locking here, at this point there must be not any
+ * reference to the list.
+ */
+ if (!list_empty(&iot->list))
+ list_for_each_entry_safe(n, p, &iot->list, node)
+ kfree(n);
+ kfree(iot);
+}
+
+/*
+ * NOTE: called with rcu_read_lock() held.
+ *
+ * do not care too much about locking for single res_counter values here.
+ */
+static void iothrottle_show_limit(struct seq_file *m, dev_t dev,
+ struct res_counter *res)
+{
+ if (!res->limit)
+ return;
+ seq_printf(m, "%u %u %llu %llu %lli %llu %li\n",
+ MAJOR(dev), MINOR(dev),
+ res->limit, res->policy,
+ (long long)res->usage, res->capacity,
+ jiffies_to_clock_t(res_counter_ratelimit_delta_t(res)));
+}
+
+/*
+ * NOTE: called with rcu_read_lock() held.
+ *
+ */
+static void iothrottle_show_failcnt(struct seq_file *m, dev_t dev,
+ struct iothrottle_stat *stat)
+{
+ unsigned long long bw_count, bw_sleep, iops_count, iops_sleep;
+
+ bw_count = iothrottle_read_stat(stat, IOTHROTTLE_STAT_BW_COUNT);
+ bw_sleep = iothrottle_read_stat(stat, IOTHROTTLE_STAT_BW_SLEEP);
+ iops_count = iothrottle_read_stat(stat, IOTHROTTLE_STAT_IOPS_COUNT);
+ iops_sleep = iothrottle_read_stat(stat, IOTHROTTLE_STAT_IOPS_SLEEP);
+
+ seq_printf(m, "%u %u %llu %li %llu %li\n", MAJOR(dev), MINOR(dev),
+ bw_count, jiffies_to_clock_t(bw_sleep),
+ iops_count, jiffies_to_clock_t(iops_sleep));
+}
+
+/*
+ * NOTE: called with rcu_read_lock() held.
+ */
+static void iothrottle_show_stat(struct seq_file *m, dev_t dev,
+ struct iothrottle_stat *stat)
+{
+ unsigned long long bytes, iops;
+
+ bytes = iothrottle_read_stat(stat, IOTHROTTLE_STAT_BYTES_TOT);
+ iops = iothrottle_read_stat(stat, IOTHROTTLE_STAT_IOPS_TOT);
+
+ seq_printf(m, "%u %u %llu %llu\n", MAJOR(dev), MINOR(dev), bytes, iops);
+}
+
+static int iothrottle_read(struct cgroup *cgrp, struct cftype *cft,
+ struct seq_file *m)
+{
+ struct iothrottle *iot = cgroup_to_iothrottle(cgrp);
+ struct iothrottle_node *n;
+
+ rcu_read_lock();
+ if (list_empty(&iot->list))
+ goto unlock_and_return;
+ list_for_each_entry_rcu(n, &iot->list, node) {
+ BUG_ON(!n->dev);
+ switch (cft->private) {
+ case IOTHROTTLE_BANDWIDTH:
+ iothrottle_show_limit(m, n->dev, &n->bw);
+ break;
+ case IOTHROTTLE_IOPS:
+ iothrottle_show_limit(m, n->dev, &n->iops);
+ break;
+ case IOTHROTTLE_FAILCNT:
+ iothrottle_show_failcnt(m, n->dev, &n->stat);
+ break;
+ case IOTHROTTLE_STAT:
+ iothrottle_show_stat(m, n->dev, &n->stat);
+ break;
+ }
+ }
+unlock_and_return:
+ rcu_read_unlock();
+ return 0;
+}
+
+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 one of the following syntaxes:
+ *
+ * dev:0 <- delete an i/o limiting rule
+ * dev:io-limit:0 <- set a leaky bucket throttling rule
+ * dev:io-limit:1:bucket-size <- set a token bucket throttling rule
+ * dev:io-limit:1 <- set a token bucket throttling rule using
+ * bucket-size == io-limit
+ */
+static int iothrottle_parse_args(char *buf, size_t nbytes, int filetype,
+ dev_t *dev, unsigned long long *iolimit,
+ unsigned long long *strategy,
+ unsigned long long *bucket_size)
+{
+ char *p;
+ int count = 0;
+ char *s[4];
+ int ret;
+
+ memset(s, 0, sizeof(s));
+ *dev = 0;
+ *iolimit = 0;
+ *strategy = 0;
+ *bucket_size = 0;
+
+ /* split the colon-delimited input string into its elements */
+ while (count < ARRAY_SIZE(s)) {
+ p = strsep(&buf, ":");
+ if (!p)
+ break;
+ if (!*p)
+ continue;
+ s[count++] = p;
+ }
+
+ /* i/o limit */
+ if (!s[1])
+ return -EINVAL;
+ ret = strict_strtoull(s[1], 10, iolimit);
+ if (ret < 0)
+ return ret;
+ if (!*iolimit)
+ goto out;
+ /* throttling strategy (leaky bucket / token bucket) */
+ if (!s[2])
+ return -EINVAL;
+ ret = strict_strtoull(s[2], 10, strategy);
+ if (ret < 0)
+ return ret;
+ switch (*strategy) {
+ case RATELIMIT_LEAKY_BUCKET:
+ goto out;
+ case RATELIMIT_TOKEN_BUCKET:
+ break;
+ default:
+ return -EINVAL;
+ }
+ /* bucket size */
+ if (!s[3])
+ *bucket_size = *iolimit;
+ else {
+ ret = strict_strtoll(s[3], 10, bucket_size);
+ if (ret < 0)
+ return ret;
+ }
+ if (*bucket_size <= 0)
+ return -EINVAL;
+out:
+ /* block device number */
+ *dev = devname2dev_t(s[0]);
+ return *dev ? 0 : -EINVAL;
+}
+
+static int iothrottle_write(struct cgroup *cgrp, struct cftype *cft,
+ const char *buffer)
+{
+ struct iothrottle *iot;
+ struct iothrottle_node *n, *newn = NULL;
+ dev_t dev;
+ unsigned long long iolimit, strategy, bucket_size;
+ char *buf;
+ size_t nbytes = strlen(buffer);
+ int ret = 0;
+
+ /*
+ * We need to allocate a new buffer here, because
+ * iothrottle_parse_args() can modify it and the buffer provided by
+ * write_string is supposed to be const.
+ */
+ buf = kmalloc(nbytes + 1, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+ memcpy(buf, buffer, nbytes + 1);
+
+ ret = iothrottle_parse_args(buf, nbytes, cft->private, &dev, &iolimit,
+ &strategy, &bucket_size);
+ if (ret)
+ goto out1;
+ newn = kzalloc(sizeof(*newn), GFP_KERNEL);
+ if (!newn) {
+ ret = -ENOMEM;
+ goto out1;
+ }
+ newn->dev = dev;
+ res_counter_init(&newn->bw);
+ res_counter_init(&newn->iops);
+
+ switch (cft->private) {
+ case IOTHROTTLE_BANDWIDTH:
+ res_counter_ratelimit_set_limit(&newn->iops, 0, 0, 0);
+ res_counter_ratelimit_set_limit(&newn->bw, strategy,
+ ALIGN(iolimit, 1024), ALIGN(bucket_size, 1024));
+ break;
+ case IOTHROTTLE_IOPS:
+ res_counter_ratelimit_set_limit(&newn->bw, 0, 0, 0);
+ /*
+ * scale up iops cost by a factor of 1000, this allows to apply
+ * a more fine grained sleeps, and throttling results more
+ * precise this way.
+ */
+ res_counter_ratelimit_set_limit(&newn->iops, strategy,
+ iolimit * 1000, bucket_size * 1000);
+ break;
+ default:
+ WARN_ON(1);
+ break;
+ }
+
+ if (!cgroup_lock_live_group(cgrp)) {
+ ret = -ENODEV;
+ goto out1;
+ }
+ iot = cgroup_to_iothrottle(cgrp);
+
+ n = iothrottle_search_node(iot, dev);
+ if (!n) {
+ if (iolimit) {
+ /* Add a new block device limiting rule */
+ iothrottle_insert_node(iot, newn);
+ newn = NULL;
+ }
+ goto out2;
+ }
+ switch (cft->private) {
+ case IOTHROTTLE_BANDWIDTH:
+ if (!iolimit && !n->iops.limit) {
+ /* Delete a block device limiting rule */
+ iothrottle_delete_node(iot, n);
+ goto out2;
+ }
+ if (!n->iops.limit)
+ break;
+ /* Update a block device limiting rule */
+ newn->iops = n->iops;
+ break;
+ case IOTHROTTLE_IOPS:
+ if (!iolimit && !n->bw.limit) {
+ /* Delete a block device limiting rule */
+ iothrottle_delete_node(iot, n);
+ goto out2;
+ }
+ if (!n->bw.limit)
+ break;
+ /* Update a block device limiting rule */
+ newn->bw = n->bw;
+ break;
+ }
+ iothrottle_replace_node(iot, n, newn);
+ newn = NULL;
+out2:
+ cgroup_unlock();
+ if (n) {
+ synchronize_rcu();
+ kfree(n);
+ }
+out1:
+ kfree(newn);
+ kfree(buf);
+ return ret;
+}
+
+static struct cftype files[] = {
+ {
+ .name = "bandwidth-max",
+ .read_seq_string = iothrottle_read,
+ .write_string = iothrottle_write,
+ .max_write_len = 256,
+ .private = IOTHROTTLE_BANDWIDTH,
+ },
+ {
+ .name = "iops-max",
+ .read_seq_string = iothrottle_read,
+ .write_string = iothrottle_write,
+ .max_write_len = 256,
+ .private = IOTHROTTLE_IOPS,
+ },
+ {
+ .name = "throttlecnt",
+ .read_seq_string = iothrottle_read,
+ .private = IOTHROTTLE_FAILCNT,
+ },
+ {
+ .name = "stat",
+ .read_seq_string = iothrottle_read,
+ .private = IOTHROTTLE_STAT,
+ },
+};
+
+static int iothrottle_populate(struct cgroup_subsys *ss, struct cgroup *cgrp)
+{
+ return cgroup_add_files(cgrp, 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,
+ .early_init = 1,
+};
+
+/*
+ * NOTE: called with rcu_read_lock() held.
+ */
+static void iothrottle_evaluate_sleep(struct iothrottle_sleep *sleep,
+ struct iothrottle *iot,
+ struct block_device *bdev, ssize_t bytes)
+{
+ struct iothrottle_node *n;
+ dev_t dev;
+
+ if (unlikely(!iot))
+ return;
+
+ /* accounting and throttling is done only on entire block devices */
+ dev = MKDEV(MAJOR(bdev->bd_inode->i_rdev), bdev->bd_disk->first_minor);
+ n = iothrottle_search_node(iot, dev);
+ if (!n)
+ return;
+
+ /* Update statistics */
+ iothrottle_stat_add(&n->stat, IOTHROTTLE_STAT_BYTES_TOT, bytes);
+ if (bytes)
+ iothrottle_stat_add(&n->stat, IOTHROTTLE_STAT_IOPS_TOT, 1);
+
+ /* Evaluate sleep values */
+ sleep->bw_sleep = res_counter_ratelimit_sleep(&n->bw, bytes);
+ /*
+ * scale up iops cost by a factor of 1000, this allows to apply
+ * a more fine grained sleeps, and throttling works better in
+ * this way.
+ *
+ * Note: do not account any i/o operation if bytes is negative or zero.
+ */
+ sleep->iops_sleep = res_counter_ratelimit_sleep(&n->iops,
+ bytes ? 1000 : 0);
+}
+
+/*
+ * NOTE: called with rcu_read_lock() held.
+ */
+static void iothrottle_acct_stat(struct iothrottle *iot,
+ struct block_device *bdev, int type,
+ unsigned long long sleep)
+{
+ struct iothrottle_node *n;
+ dev_t dev = MKDEV(MAJOR(bdev->bd_inode->i_rdev),
+ bdev->bd_disk->first_minor);
+
+ n = iothrottle_search_node(iot, dev);
+ if (!n)
+ return;
+ iothrottle_stat_add_sleep(&n->stat, type, sleep);
+}
+
+static void iothrottle_acct_task_stat(int type, unsigned long long sleep)
+{
+ /*
+ * XXX: per-task statistics may be inaccurate (this is not a
+ * critical issue, anyway, respect to introduce locking
+ * overhead or increase the size of task_struct).
+ */
+ switch (type) {
+ case IOTHROTTLE_BANDWIDTH:
+ current->io_throttle_bw_cnt++;
+ current->io_throttle_bw_sleep += sleep;
+ break;
+
+ case IOTHROTTLE_IOPS:
+ current->io_throttle_iops_cnt++;
+ current->io_throttle_iops_sleep += sleep;
+ break;
+ }
+}
+
+static struct iothrottle *get_iothrottle_from_page(struct page *page)
+{
+ struct cgroup *cgrp;
+ struct iothrottle *iot;
+
+ if (!page)
+ return NULL;
+ cgrp = get_cgroup_from_page(page);
+ if (!cgrp)
+ return NULL;
+ iot = cgroup_to_iothrottle(cgrp);
+ css_get(&iot->css);
+ put_cgroup_from_page(page);
+
+ return iot;
+}
+
+static inline int is_kthread_io(void)
+{
+ return current->flags & (PF_KTHREAD | PF_FLUSHER | PF_KSWAPD);
+}
+
+/**
+ * cgroup_io_throttle() - account and throttle i/o activity
+ * @page: a page used to retrieve the owner of the i/o operation.
+ * @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.
+ *
+ * Returns the value of sleep in jiffies if it was not possible to schedule the
+ * timeout.
+ **/
+unsigned long long
+cgroup_io_throttle(struct page *page, struct block_device *bdev,
+ ssize_t bytes, int can_sleep)
+{
+ struct iothrottle *iot;
+ struct iothrottle_sleep s = {};
+ unsigned long long sleep;
+
+ if (unlikely(!bdev))
+ return 0;
+ BUG_ON(!bdev->bd_inode || !bdev->bd_disk);
+ /*
+ * Never throttle kernel threads, since they may completely block other
+ * cgroups, the i/o on other block devices or even the whole system.
+ *
+ * And never sleep also if we're inside an AIO context; just account
+ * the i/o activity. Throttling is performed in io_submit_one()
+ * returning * -EAGAIN when the limits are exceeded.
+ */
+ if (is_kthread_io() || is_in_aio())
+ can_sleep = 0;
+ /*
+ * WARNING: in_atomic() do not know about held spinlocks in
+ * non-preemptible kernels, but we want to check it here to raise
+ * potential bugs by preemptible kernels.
+ */
+ WARN_ON_ONCE(can_sleep &&
+ (irqs_disabled() || in_interrupt() || in_atomic()));
+
+ /* check if we need to throttle */
+ iot = get_iothrottle_from_page(page);
+ rcu_read_lock();
+ if (!iot) {
+ iot = task_to_iothrottle(current);
+ css_get(&iot->css);
+ }
+ iothrottle_evaluate_sleep(&s, iot, bdev, bytes);
+ sleep = max(s.bw_sleep, s.iops_sleep);
+ if (unlikely(sleep && can_sleep)) {
+ int type = (s.bw_sleep < s.iops_sleep) ?
+ IOTHROTTLE_IOPS : IOTHROTTLE_BANDWIDTH;
+
+ iothrottle_acct_stat(iot, bdev, type, sleep);
+ css_put(&iot->css);
+ rcu_read_unlock();
+
+ pr_debug("io-throttle: task %p (%s) must sleep %llu jiffies\n",
+ current, current->comm, sleep);
+ iothrottle_acct_task_stat(type, sleep);
+ schedule_timeout_killable(sleep);
+ return 0;
+ }
+ css_put(&iot->css);
+ rcu_read_unlock();
+ return sleep;
+}
diff --git a/fs/aio.c b/fs/aio.c
index f658441..ee8d452 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -22,6 +22,7 @@
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/file.h>
+#include <linux/blk-io-throttle.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/slab.h>
@@ -1558,6 +1559,7 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
{
struct kiocb *req;
struct file *file;
+ struct block_device *bdev;
ssize_t ret;

/* enforce forwards compatibility on users */
@@ -1580,6 +1582,14 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
if (unlikely(!file))
return -EBADF;

+ /* check if we're exceeding the IO throttling limits */
+ bdev = as_to_bdev(file->f_mapping);
+ ret = cgroup_io_throttle(NULL, bdev, 0, 0);
+ if (unlikely(ret)) {
+ fput(file);
+ return -EAGAIN;
+ }
+
req = aio_get_req(ctx); /* returns with 2 references to req */
if (unlikely(!req)) {
fput(file);
@@ -1622,12 +1632,14 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
goto out_put_req;

spin_lock_irq(&ctx->ctx_lock);
+ set_in_aio();
aio_run_iocb(req);
if (!list_empty(&ctx->run_list)) {
/* drain the run list */
while (__aio_run_iocbs(ctx))
;
}
+ unset_in_aio();
spin_unlock_irq(&ctx->ctx_lock);
aio_put_req(req); /* drop extra ref to req */
return 0;
diff --git a/fs/direct-io.c b/fs/direct-io.c
index 222a970..cd78bab 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -28,6 +28,7 @@
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/task_io_accounting_ops.h>
+#include <linux/blk-io-throttle.h>
#include <linux/bio.h>
#include <linux/wait.h>
#include <linux/err.h>
@@ -658,10 +659,12 @@ submit_page_section(struct dio *dio, struct page *page,
int ret = 0;

if (dio->rw & WRITE) {
+ struct block_device *bdev = dio->inode->i_sb->s_bdev;
/*
* Read accounting is performed in submit_bio()
*/
task_io_account_write(len);
+ cgroup_io_throttle(NULL, bdev, 0, 1);
}

/*
diff --git a/fs/proc/base.c b/fs/proc/base.c
index cf42c42..9d2574a 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -54,6 +54,7 @@
#include <linux/proc_fs.h>
#include <linux/stat.h>
#include <linux/task_io_accounting_ops.h>
+#include <linux/blk-io-throttle.h>
#include <linux/init.h>
#include <linux/capability.h>
#include <linux/file.h>
@@ -2458,6 +2459,17 @@ static int proc_pid_personality(struct seq_file *m, struct pid_namespace *ns,
return 0;
}

+#ifdef CONFIG_CGROUP_IO_THROTTLE
+static int proc_iothrottle_stat(struct task_struct *task, char *buffer)
+{
+ return sprintf(buffer, "%llu %llu %llu %llu\n",
+ get_io_throttle_cnt(task, IOTHROTTLE_BANDWIDTH),
+ get_io_throttle_sleep(task, IOTHROTTLE_BANDWIDTH),
+ get_io_throttle_cnt(task, IOTHROTTLE_IOPS),
+ get_io_throttle_sleep(task, IOTHROTTLE_IOPS));
+}
+#endif /* CONFIG_CGROUP_IO_THROTTLE */
+
/*
* Thread groups
*/
@@ -2534,6 +2546,9 @@ static const struct pid_entry tgid_base_stuff[] = {
#ifdef CONFIG_TASK_IO_ACCOUNTING
INF("io", S_IRUGO, tgid_io_accounting),
#endif
+#ifdef CONFIG_CGROUP_IO_THROTTLE
+ INF("io-throttle-stat", S_IRUGO, iothrottle_stat),
+#endif
};

static int proc_tgid_base_readdir(struct file * filp,
@@ -2866,6 +2881,9 @@ static const struct pid_entry tid_base_stuff[] = {
#ifdef CONFIG_TASK_IO_ACCOUNTING
INF("io", S_IRUGO, tid_io_accounting),
#endif
+#ifdef CONFIG_CGROUP_IO_THROTTLE
+ INF("io-throttle-stat", S_IRUGO, iothrottle_stat),
+#endif
};

static int proc_tid_base_readdir(struct file * filp,
diff --git a/include/linux/blk-io-throttle.h b/include/linux/blk-io-throttle.h
new file mode 100644
index 0000000..a241758
--- /dev/null
+++ b/include/linux/blk-io-throttle.h
@@ -0,0 +1,95 @@
+#ifndef BLK_IO_THROTTLE_H
+#define BLK_IO_THROTTLE_H
+
+#include <linux/fs.h>
+#include <linux/jiffies.h>
+#include <linux/sched.h>
+#include <linux/cgroup.h>
+#include <asm/atomic.h>
+#include <asm/current.h>
+
+#define IOTHROTTLE_BANDWIDTH 0
+#define IOTHROTTLE_IOPS 1
+#define IOTHROTTLE_FAILCNT 2
+#define IOTHROTTLE_STAT 3
+
+#ifdef CONFIG_CGROUP_IO_THROTTLE
+extern unsigned long long
+cgroup_io_throttle(struct page *page, struct block_device *bdev,
+ ssize_t bytes, int can_sleep);
+
+static inline void set_in_aio(void)
+{
+ atomic_set(&current->in_aio, 1);
+}
+
+static inline void unset_in_aio(void)
+{
+ atomic_set(&current->in_aio, 0);
+}
+
+static inline int is_in_aio(void)
+{
+ return atomic_read(&current->in_aio);
+}
+
+static inline unsigned long long
+get_io_throttle_cnt(struct task_struct *t, int type)
+{
+ switch (type) {
+ case IOTHROTTLE_BANDWIDTH:
+ return t->io_throttle_bw_cnt;
+ case IOTHROTTLE_IOPS:
+ return t->io_throttle_iops_cnt;
+ }
+ BUG();
+}
+
+static inline unsigned long long
+get_io_throttle_sleep(struct task_struct *t, int type)
+{
+ switch (type) {
+ case IOTHROTTLE_BANDWIDTH:
+ return jiffies_to_clock_t(t->io_throttle_bw_sleep);
+ case IOTHROTTLE_IOPS:
+ return jiffies_to_clock_t(t->io_throttle_iops_sleep);
+ }
+ BUG();
+}
+#else
+static inline unsigned long long
+cgroup_io_throttle(struct page *page, struct block_device *bdev,
+ ssize_t bytes, int can_sleep)
+{
+ return 0;
+}
+
+static inline void set_in_aio(void) { }
+
+static inline void unset_in_aio(void) { }
+
+static inline int is_in_aio(void)
+{
+ return 0;
+}
+
+static inline unsigned long long
+get_io_throttle_cnt(struct task_struct *t, int type)
+{
+ return 0;
+}
+
+static inline unsigned long long
+get_io_throttle_sleep(struct task_struct *t, int type)
+{
+ return 0;
+}
+#endif /* CONFIG_CGROUP_IO_THROTTLE */
+
+static inline struct block_device *as_to_bdev(struct address_space *mapping)
+{
+ return (mapping->host && mapping->host->i_sb->s_bdev) ?
+ mapping->host->i_sb->s_bdev : NULL;
+}
+
+#endif /* BLK_IO_THROTTLE_H */
diff --git a/include/linux/cgroup_subsys.h b/include/linux/cgroup_subsys.h
index 8eb6f48..97277c9 100644
--- a/include/linux/cgroup_subsys.h
+++ b/include/linux/cgroup_subsys.h
@@ -55,6 +55,12 @@ SUBSYS(devices)

/* */

+#ifdef CONFIG_CGROUP_IO_THROTTLE
+SUBSYS(iothrottle)
+#endif
+
+/* */
+
#ifdef CONFIG_CGROUP_FREEZER
SUBSYS(freezer)
#endif
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index f519a88..009e5e4 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -20,7 +20,7 @@
#ifndef _LINUX_MEMCONTROL_H
#define _LINUX_MEMCONTROL_H

-#struct mem_cgroup;
+struct mem_cgroup;
struct page_cgroup;
struct page;
struct mm_struct;
@@ -49,6 +49,9 @@ int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *mem);

extern struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p);

+extern struct cgroup *get_cgroup_from_page(struct page *page);
+extern void put_cgroup_from_page(struct page *page);
+
#define mm_match_cgroup(mm, cgroup) \
((cgroup) == mem_cgroup_from_task((mm)->owner))

diff --git a/include/linux/res_counter.h b/include/linux/res_counter.h
index 271c1c2..0cb9251 100644
--- a/include/linux/res_counter.h
+++ b/include/linux/res_counter.h
@@ -14,30 +14,36 @@
*/

#include <linux/cgroup.h>
+#include <linux/jiffies.h>

-/*
- * The core object. the cgroup that wishes to account for some
- * resource may include this counter into its structures and use
- * the helpers described beyond
- */
+/* The various policies that can be used for ratelimiting resources */
+#define RATELIMIT_LEAKY_BUCKET 0
+#define RATELIMIT_TOKEN_BUCKET 1

+/**
+ * struct res_counter - the core object to account cgroup resources
+ *
+ * @usage: the current resource consumption level
+ * @max_usage: the maximal value of the usage from the counter creation
+ * @limit: the limit that usage cannot be exceeded
+ * @failcnt: the number of unsuccessful attempts to consume the resource
+ * @policy: the limiting policy / algorithm
+ * @capacity: the maximum capacity of the resource
+ * @timestamp: timestamp of the last accounted resource request
+ * @lock: the lock to protect all of the above.
+ * The routines below consider this to be IRQ-safe
+ *
+ * The cgroup that wishes to account for some resource may include this counter
+ * into its structures and use the helpers described beyond.
+ */
struct res_counter {
- /*
- * the current resource consumption level
- */
unsigned long long usage;
- /*
- * the maximal value of the usage from the counter creation
- */
unsigned long long max_usage;
- /*
- * the limit that usage cannot exceed
- */
unsigned long long limit;
- /*
- * the number of unsuccessful attempts to consume the resource
- */
unsigned long long failcnt;
+ unsigned long long policy;
+ unsigned long long capacity;
+ unsigned long long timestamp;
/*
* the lock to protect all of the above.
* the routines below consider this to be IRQ-safe
@@ -80,6 +86,9 @@ enum {
RES_USAGE,
RES_MAX_USAGE,
RES_LIMIT,
+ RES_POLICY,
+ RES_TIMESTAMP,
+ RES_CAPACITY,
RES_FAILCNT,
};

@@ -126,6 +135,15 @@ static inline bool res_counter_limit_check_locked(struct res_counter *cnt)
return false;
}

+static inline unsigned long long
+res_counter_ratelimit_delta_t(struct res_counter *res)
+{
+ return (long long)get_jiffies_64() - (long long)res->timestamp;
+}
+
+unsigned long long
+res_counter_ratelimit_sleep(struct res_counter *res, ssize_t val);
+
/*
* Helper function to detect if the cgroup is within it's limit or
* not. It's currently called from cgroup_rss_prepare()
@@ -159,6 +177,23 @@ static inline void res_counter_reset_failcnt(struct res_counter *cnt)
spin_unlock_irqrestore(&cnt->lock, flags);
}

+static inline int
+res_counter_ratelimit_set_limit(struct res_counter *cnt,
+ unsigned long long policy,
+ unsigned long long limit, unsigned long long max)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&cnt->lock, flags);
+ cnt->limit = limit;
+ cnt->capacity = max;
+ cnt->policy = policy;
+ cnt->timestamp = get_jiffies_64();
+ cnt->usage = 0;
+ spin_unlock_irqrestore(&cnt->lock, flags);
+ return 0;
+}
+
static inline int res_counter_set_limit(struct res_counter *cnt,
unsigned long long limit)
{
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 346616d..49426be 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1250,6 +1250,13 @@ struct task_struct {
unsigned long ptrace_message;
siginfo_t *last_siginfo; /* For ptrace use. */
struct task_io_accounting ioac;
+#ifdef CONFIG_CGROUP_IO_THROTTLE
+ atomic_t in_aio;
+ unsigned long long io_throttle_bw_cnt;
+ unsigned long long io_throttle_bw_sleep;
+ unsigned long long io_throttle_iops_cnt;
+ unsigned long long io_throttle_iops_sleep;
+#endif
#if defined(CONFIG_TASK_XACCT)
u64 acct_rss_mem1; /* accumulated rss usage */
u64 acct_vm_mem1; /* accumulated virtual memory usage */
diff --git a/init/Kconfig b/init/Kconfig
index 6394a25..06649c5 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -313,6 +313,16 @@ 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 && CGROUP_MEM_RES_CTLR && RESOURCE_COUNTERS && 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
diff --git a/kernel/fork.c b/kernel/fork.c
index dba2d3f..8188067 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1025,6 +1025,14 @@ static struct task_struct *copy_process(unsigned long clone_flags,
task_io_accounting_init(&p->ioac);
acct_clear_integrals(p);

+#ifdef CONFIG_CGROUP_IO_THROTTLE
+ atomic_set(&p->in_aio, 0);
+ p->io_throttle_bw_cnt = 0;
+ p->io_throttle_bw_sleep = 0;
+ p->io_throttle_iops_cnt = 0;
+ p->io_throttle_iops_sleep = 0;
+#endif
+
posix_cpu_timers_init(p);

p->lock_depth = -1; /* -1 = no lock */
diff --git a/kernel/res_counter.c b/kernel/res_counter.c
index f275c8e..e55c674 100644
--- a/kernel/res_counter.c
+++ b/kernel/res_counter.c
@@ -9,6 +9,7 @@

#include <linux/types.h>
#include <linux/parser.h>
+#include <linux/jiffies.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/res_counter.h>
@@ -19,6 +20,8 @@ void res_counter_init(struct res_counter *counter)
{
spin_lock_init(&counter->lock);
counter->limit = (unsigned long long)LLONG_MAX;
+ counter->capacity = (unsigned long long)LLONG_MAX;
+ counter->timestamp = get_jiffies_64();
}

int res_counter_charge_locked(struct res_counter *counter, unsigned long val)
@@ -62,7 +65,6 @@ void res_counter_uncharge(struct res_counter *counter, unsigned long val)
spin_unlock_irqrestore(&counter->lock, flags);
}

-
static inline unsigned long long *
res_counter_member(struct res_counter *counter, int member)
{
@@ -73,6 +75,12 @@ res_counter_member(struct res_counter *counter, int member)
return &counter->max_usage;
case RES_LIMIT:
return &counter->limit;
+ case RES_POLICY:
+ return &counter->policy;
+ case RES_TIMESTAMP:
+ return &counter->timestamp;
+ case RES_CAPACITY:
+ return &counter->capacity;
case RES_FAILCNT:
return &counter->failcnt;
};
@@ -137,3 +145,66 @@ int res_counter_write(struct res_counter *counter, int member,
spin_unlock_irqrestore(&counter->lock, flags);
return 0;
}
+
+static unsigned long long
+ratelimit_leaky_bucket(struct res_counter *res, ssize_t val)
+{
+ unsigned long long delta, t;
+
+ res->usage += val;
+ delta = res_counter_ratelimit_delta_t(res);
+ if (!delta)
+ return 0;
+ t = res->usage * USEC_PER_SEC;
+ t = usecs_to_jiffies(div_u64(t, res->limit));
+ if (t > delta)
+ return t - delta;
+ /* Reset i/o statistics */
+ res->usage = 0;
+ res->timestamp = get_jiffies_64();
+ return 0;
+}
+
+static unsigned long long
+ratelimit_token_bucket(struct res_counter *res, ssize_t val)
+{
+ unsigned long long delta;
+ long long tok;
+
+ res->usage -= val;
+ delta = jiffies_to_msecs(res_counter_ratelimit_delta_t(res));
+ res->timestamp = get_jiffies_64();
+ tok = (long long)res->usage * MSEC_PER_SEC;
+ if (delta) {
+ long long max = (long long)res->capacity * MSEC_PER_SEC;
+
+ tok += delta * res->limit;
+ if (tok > max)
+ tok = max;
+ res->usage = (unsigned long long)div_s64(tok, MSEC_PER_SEC);
+ }
+ return (tok < 0) ? msecs_to_jiffies(div_u64(-tok, res->limit)) : 0;
+}
+
+unsigned long long
+res_counter_ratelimit_sleep(struct res_counter *res, ssize_t val)
+{
+ unsigned long long sleep = 0;
+ unsigned long flags;
+
+ spin_lock_irqsave(&res->lock, flags);
+ if (res->limit)
+ switch (res->policy) {
+ case RATELIMIT_LEAKY_BUCKET:
+ sleep = ratelimit_leaky_bucket(res, val);
+ break;
+ case RATELIMIT_TOKEN_BUCKET:
+ sleep = ratelimit_token_bucket(res, val);
+ break;
+ default:
+ WARN_ON(1);
+ break;
+ }
+ spin_unlock_irqrestore(&res->lock, flags);
+ return sleep;
+}
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 95048fe..097278c 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -241,6 +241,36 @@ struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
struct mem_cgroup, css);
}

+struct cgroup *get_cgroup_from_page(struct page *page)
+{
+ struct page_cgroup *pc;
+ struct cgroup *cgrp = NULL;
+
+ pc = lookup_page_cgroup(page);
+ if (pc) {
+ lock_page_cgroup(pc);
+ if(pc->mem_cgroup) {
+ css_get(&pc->mem_cgroup->css);
+ cgrp = pc->mem_cgroup->css.cgroup;
+ }
+ unlock_page_cgroup(pc);
+ }
+
+ return cgrp;
+}
+
+void put_cgroup_from_page(struct page *page)
+{
+ struct page_cgroup *pc;
+
+ pc = lookup_page_cgroup(page);
+ if (pc) {
+ lock_page_cgroup(pc);
+ css_put(&pc->mem_cgroup->css);
+ unlock_page_cgroup(pc);
+ }
+}
+
static void __mem_cgroup_remove_list(struct mem_cgroup_per_zone *mz,
struct page_cgroup *pc)
{
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index f24daaa..6112fa4 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -20,6 +20,7 @@
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/writeback.h>
+#include <linux/blk-io-throttle.h>
#include <linux/init.h>
#include <linux/backing-dev.h>
#include <linux/task_io_accounting_ops.h>
@@ -557,6 +558,9 @@ void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
static DEFINE_PER_CPU(unsigned long, ratelimits) = 0;
unsigned long ratelimit;
unsigned long *p;
+ struct block_device *bdev = as_to_bdev(mapping);
+
+ cgroup_io_throttle(NULL, bdev, 0, 1);

ratelimit = ratelimit_pages;
if (mapping->backing_dev_info->dirty_exceeded)
diff --git a/mm/readahead.c b/mm/readahead.c
index bec83c1..7debb81 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -14,6 +14,7 @@
#include <linux/blkdev.h>
#include <linux/backing-dev.h>
#include <linux/task_io_accounting_ops.h>
+#include <linux/blk-io-throttle.h>
#include <linux/pagevec.h>
#include <linux/pagemap.h>

@@ -58,6 +59,7 @@ int read_cache_pages(struct address_space *mapping, struct list_head *pages,
int (*filler)(void *, struct page *), void *data)
{
struct page *page;
+ struct block_device *bdev = as_to_bdev(mapping);
int ret = 0;

while (!list_empty(pages)) {
@@ -76,6 +78,7 @@ int read_cache_pages(struct address_space *mapping, struct list_head *pages,
break;
}
task_io_account_read(PAGE_CACHE_SIZE);
+ cgroup_io_throttle(NULL, bdev, PAGE_CACHE_SIZE, 1);
}
return ret;
}
-- 1.5.4.rc3


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