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Date: Fri, 03 Sep 2010 17:50:55 +0800
From: Gui Jianfeng <guijianfeng@...fujitsu.com>
To: Vivek Goyal <vgoyal@...hat.com>
CC: linux kernel mailing list <linux-kernel@...r.kernel.org>,
Jens Axboe <axboe@...nel.dk>,
Nauman Rafique <nauman@...gle.com>,
Divyesh Shah <dpshah@...gle.com>,
Heinz Mauelshagen <heinzm@...hat.com>, arighi@...eler.com
Subject: Re: [RFC PATCH] Bio Throttling support for block IO controller
Vivek Goyal wrote:
> Hi,
>
> Currently CFQ provides the weight based proportional division of bandwidth.
> People also have been looking at extending block IO controller to provide
> throttling/max bandwidth control.
>
> I have started to write the support for throttling in block layer on
> request queue so that it can be used both for higher level logical
> devices as well as leaf nodes. This patch is still work in progress but
> I wanted to post it for early feedback.
>
> Basically currently I have hooked into __make_request() function to
> check which cgroup bio belongs to and if it is exceeding the specified
> BW rate. If no, thread can continue to dispatch bio as it is otherwise
> bio is queued internally and dispatched later with the help of a worker
Hi Vivek,
I'd like to give it a try.
In what manner the worker dispatch bios? FIFO? I have yet gone throught the patch.
Thanks
Gui
> thread.
>
> HOWTO
> =====
> - Mount blkio controller
> mount -t cgroup -o blkio none /cgroup/blkio
>
> - Specify a bandwidth rate on particular device for root group. The format
> for policy is "<major>:<minor> <byes_per_second>".
>
> echo "8:16 1048576" > /cgroup/blkio/blkio.read_bps_device
>
> Above will put a limit of 1MB/second on reads happening for root group
> on device having major/minor number 8:16.
>
> - Run dd to read a file and see if rate is throttled to 1MB/s or not.
>
> # dd if=/mnt/common/zerofile of=/dev/null bs=4K count=1024 iflag=direct
> 1024+0 records in
> 1024+0 records out
> 4194304 bytes (4.2 MB) copied, 4.0001 s, 1.0 MB/s
>
> Limits for writes can be put using blkio.write_bps_device file.
>
> Open Issues
> ===========
> - Do we need to provide additional queue congestion semantics as we are
> throttling and queuing bios at request queue and probably we don't want
> a user space application to consume all the memory allocating bios
> and bombarding request queue with those bios.
>
> - How to handle the current blkio cgroup stats file and two policies
> in the background. If for some reason both throttling and proportional
> BW policies are operating on request queue, then stats will be very
> confusing.
>
> May be we can allow activating either throttling or proportional BW
> policy per request queue and we can create a /sys tunable to list and
> chose between policies (something like choosing IO scheduler). The
> only downside of this apporach is that user also need to be aware of
> the storage hierachy and activate right policy at each node/request
> queue.
>
> TODO
> ====
> - Lots of testing, bug fixes.
> - Provide support for enforcing limits in IOPS.
> - Extend the throttling support for dm devices also.
>
> Any feedback is welcome.
>
> Thanks
> Vivek
>
> o IO throttling support in block layer.
>
> Signed-off-by: Vivek Goyal <vgoyal@...hat.com>
> ---
> block/Makefile | 2
> block/blk-cgroup.c | 282 +++++++++++--
> block/blk-cgroup.h | 44 ++
> block/blk-core.c | 28 +
> block/blk-throttle.c | 928 ++++++++++++++++++++++++++++++++++++++++++++++
> block/blk.h | 4
> block/cfq-iosched.c | 4
> include/linux/blk_types.h | 3
> include/linux/blkdev.h | 22 +
> 9 files changed, 1261 insertions(+), 56 deletions(-)
>
> Index: linux-2.6/block/blk-core.c
> ===================================================================
> --- linux-2.6.orig/block/blk-core.c 2010-09-01 10:54:53.000000000 -0400
> +++ linux-2.6/block/blk-core.c 2010-09-01 10:56:56.000000000 -0400
> @@ -382,6 +382,7 @@ void blk_sync_queue(struct request_queue
> del_timer_sync(&q->unplug_timer);
> del_timer_sync(&q->timeout);
> cancel_work_sync(&q->unplug_work);
> + throtl_shutdown_timer_wq(q);
> }
> EXPORT_SYMBOL(blk_sync_queue);
>
> @@ -459,6 +460,8 @@ void blk_cleanup_queue(struct request_qu
> if (q->elevator)
> elevator_exit(q->elevator);
>
> + blk_throtl_exit(q);
> +
> blk_put_queue(q);
> }
> EXPORT_SYMBOL(blk_cleanup_queue);
> @@ -515,13 +518,17 @@ struct request_queue *blk_alloc_queue_no
> return NULL;
> }
>
> + if (blk_throtl_init(q)) {
> + kmem_cache_free(blk_requestq_cachep, q);
> + return NULL;
> + }
> +
> setup_timer(&q->backing_dev_info.laptop_mode_wb_timer,
> laptop_mode_timer_fn, (unsigned long) q);
> init_timer(&q->unplug_timer);
> setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
> INIT_LIST_HEAD(&q->timeout_list);
> INIT_WORK(&q->unplug_work, blk_unplug_work);
> -
> kobject_init(&q->kobj, &blk_queue_ktype);
>
> mutex_init(&q->sysfs_lock);
> @@ -1217,7 +1224,17 @@ static int __make_request(struct request
>
> spin_lock_irq(q->queue_lock);
>
> - if (unlikely((bio->bi_rw & REQ_HARDBARRIER)) || elv_queue_empty(q))
> + if (unlikely((bio->bi_rw & REQ_HARDBARRIER)))
> + goto get_rq;
> +
> + /* Hook for bandwidth control */
> + blk_throtl_bio(q, &bio);
> +
> + /* If !bio, bio has been throttled and will be submitted later */
> + if (!bio)
> + goto out;
> +
> + if (elv_queue_empty(q))
> goto get_rq;
>
> el_ret = elv_merge(q, &req, bio);
> @@ -2579,6 +2596,13 @@ int kblockd_schedule_work(struct request
> }
> EXPORT_SYMBOL(kblockd_schedule_work);
>
> +int kblockd_schedule_delayed_work(struct request_queue *q,
> + struct delayed_work *dwork, unsigned long delay)
> +{
> + return queue_delayed_work(kblockd_workqueue, dwork, delay);
> +}
> +EXPORT_SYMBOL(kblockd_schedule_delayed_work);
> +
> int __init blk_dev_init(void)
> {
> BUILD_BUG_ON(__REQ_NR_BITS > 8 *
> Index: linux-2.6/include/linux/blkdev.h
> ===================================================================
> --- linux-2.6.orig/include/linux/blkdev.h 2010-09-01 10:54:53.000000000 -0400
> +++ linux-2.6/include/linux/blkdev.h 2010-09-01 10:56:56.000000000 -0400
> @@ -367,6 +367,11 @@ struct request_queue
> #if defined(CONFIG_BLK_DEV_BSG)
> struct bsg_class_device bsg_dev;
> #endif
> +
> +#ifdef CONFIG_BLK_CGROUP
> + /* Throttle data */
> + struct throtl_data *td;
> +#endif
> };
>
> #define QUEUE_FLAG_CLUSTER 0 /* cluster several segments into 1 */
> @@ -1127,6 +1132,7 @@ static inline void put_dev_sector(Sector
>
> struct work_struct;
> int kblockd_schedule_work(struct request_queue *q, struct work_struct *work);
> +int kblockd_schedule_delayed_work(struct request_queue *q, struct delayed_work *dwork, unsigned long delay);
>
> #ifdef CONFIG_BLK_CGROUP
> /*
> @@ -1157,6 +1163,12 @@ static inline uint64_t rq_io_start_time_
> {
> return req->io_start_time_ns;
> }
> +
> +extern int blk_throtl_init(struct request_queue *q);
> +extern void blk_throtl_exit(struct request_queue *q);
> +extern int blk_throtl_bio(struct request_queue *q, struct bio **bio);
> +extern void throtl_schedule_delayed_work(struct request_queue *q, unsigned long delay);
> +extern void throtl_shutdown_timer_wq(struct request_queue *q);
> #else
> static inline void set_start_time_ns(struct request *req) {}
> static inline void set_io_start_time_ns(struct request *req) {}
> @@ -1168,6 +1180,16 @@ static inline uint64_t rq_io_start_time_
> {
> return 0;
> }
> +
> +static inline int blk_throtl_bio(struct request_queue *q, struct bio **bio)
> +{
> + return 0;
> +}
> +
> +static inline int blk_throtl_init(struct request_queue *q) { return 0; }
> +static inline int blk_throtl_exit(struct request_queue *q) { return 0; }
> +static inline void throtl_schedule_delayed_work(struct request_queue *q, unsigned long delay) {}
> +static inline void throtl_shutdown_timer_wq(struct request_queue *q) {}
> #endif
>
> #define MODULE_ALIAS_BLOCKDEV(major,minor) \
> Index: linux-2.6/block/Makefile
> ===================================================================
> --- linux-2.6.orig/block/Makefile 2010-09-01 10:54:53.000000000 -0400
> +++ linux-2.6/block/Makefile 2010-09-01 10:56:56.000000000 -0400
> @@ -8,7 +8,7 @@ obj-$(CONFIG_BLOCK) := elevator.o blk-co
> blk-iopoll.o blk-lib.o ioctl.o genhd.o scsi_ioctl.o
>
> obj-$(CONFIG_BLK_DEV_BSG) += bsg.o
> -obj-$(CONFIG_BLK_CGROUP) += blk-cgroup.o
> +obj-$(CONFIG_BLK_CGROUP) += blk-cgroup.o blk-throttle.o
> obj-$(CONFIG_IOSCHED_NOOP) += noop-iosched.o
> obj-$(CONFIG_IOSCHED_DEADLINE) += deadline-iosched.o
> obj-$(CONFIG_IOSCHED_CFQ) += cfq-iosched.o
> Index: linux-2.6/block/blk-throttle.c
> ===================================================================
> --- /dev/null 1970-01-01 00:00:00.000000000 +0000
> +++ linux-2.6/block/blk-throttle.c 2010-09-01 10:56:56.000000000 -0400
> @@ -0,0 +1,928 @@
> +/*
> + * Interface for controlling IO bandwidth on a request queue
> + *
> + * Copyright (C) 2010 Vivek Goyal <vgoyal@...hat.com>
> + */
> +
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/blkdev.h>
> +#include <linux/bio.h>
> +#include <linux/blktrace_api.h>
> +#include "blk-cgroup.h"
> +
> +/* Max dispatch from a group in 1 round */
> +static int throtl_grp_quantum = 8;
> +
> +/* Total max dispatch from all groups in one round */
> +static int throtl_quantum = 32;
> +
> +/* Throttling is performed over 100ms slice and after that slice is renewed */
> +static unsigned long throtl_slice = HZ/10; /* 100 ms */
> +
> +struct throtl_rb_root {
> + struct rb_root rb;
> + struct rb_node *left;
> + unsigned int count;
> + unsigned long min_disptime;
> +};
> +
> +#define THROTL_RB_ROOT (struct throtl_rb_root) { .rb = RB_ROOT, .left = NULL, \
> + .count = 0, .min_disptime = 0}
> +
> +#define rb_entry_tg(node) rb_entry((node), struct throtl_grp, rb_node)
> +
> +struct throtl_grp {
> + /* List of throtl groups on the request queue*/
> + struct hlist_node tg_node;
> +
> + /* active throtl group service_tree member */
> + struct rb_node rb_node;
> +
> + /*
> + * Dispatch time in jiffies. This is the estimated time when group
> + * will unthrottle and is ready to dispatch more bio. It is used as
> + * key to sort active groups in service tree.
> + */
> + unsigned long disptime;
> +
> + struct blkio_group blkg;
> + atomic_t ref;
> + unsigned int flags;
> +
> + /* Two lists for READ and WRITE */
> + struct bio_list bio_lists[2];
> +
> + /* Number of queued bios on READ and WRITE lists */
> + unsigned int nr_queued[2];
> +
> + /* bytes per second rate limits */
> + uint64_t bps[2];
> +
> + /* Number of bytes disptached in current slice */
> + uint64_t bytes_disp[2];
> +
> + /* When did we start a new slice */
> + unsigned long slice_start[2];
> + unsigned long slice_end[2];
> +};
> +
> +struct throtl_data
> +{
> + /* List of throtl groups */
> + struct hlist_head tg_list;
> +
> + /* service tree for active throtl groups */
> + struct throtl_rb_root tg_service_tree;
> +
> + struct throtl_grp root_tg;
> + struct request_queue *queue;
> +
> + /* Total Number of queued bios on READ and WRITE lists */
> + unsigned int nr_queued[2];
> +
> + /* How many bios are on disp_list */
> + int nr_disp_list;
> +
> + /*
> + * number of total undestroyed groups (excluding root group)
> + */
> + unsigned int nr_undestroyed_grps;
> +
> + /* Bios queued for dispatch */
> + struct bio_list disp_list;
> +
> + /* Work for dispatching throttled bios */
> + struct delayed_work throtl_work;
> +};
> +
> +enum tg_state_flags {
> + THROTL_TG_FLAG_on_rr = 0, /* on round-robin busy list */
> +};
> +
> +#define THROTL_TG_FNS(name) \
> +static inline void throtl_mark_tg_##name(struct throtl_grp *tg) \
> +{ \
> + (tg)->flags |= (1 << THROTL_TG_FLAG_##name); \
> +} \
> +static inline void throtl_clear_tg_##name(struct throtl_grp *tg) \
> +{ \
> + (tg)->flags &= ~(1 << THROTL_TG_FLAG_##name); \
> +} \
> +static inline int throtl_tg_##name(const struct throtl_grp *tg) \
> +{ \
> + return ((tg)->flags & (1 << THROTL_TG_FLAG_##name)) != 0; \
> +}
> +
> +THROTL_TG_FNS(on_rr);
> +
> +#define throtl_log_tg(td, tg, fmt, args...) \
> + blk_add_trace_msg((td)->queue, "%s throtl " fmt, \
> + blkg_path(&(tg)->blkg), ##args); \
> +
> +#define throtl_log(td, fmt, args...) \
> + blk_add_trace_msg((td)->queue, "throtl " fmt, ##args)
> +
> +static inline struct throtl_grp *tg_of_blkg(struct blkio_group *blkg)
> +{
> + if (blkg)
> + return container_of(blkg, struct throtl_grp, blkg);
> +
> + return NULL;
> +}
> +
> +static inline int total_nr_queued(struct throtl_data *td)
> +{
> + return (td->nr_disp_list + td->nr_queued[0] + td->nr_queued[1]);
> +}
> +
> +static inline struct throtl_grp *throtl_ref_get_tg(struct throtl_grp *tg)
> +{
> + atomic_inc(&tg->ref);
> + return tg;
> +}
> +
> +static void throtl_put_tg(struct throtl_grp *tg)
> +{
> + BUG_ON(atomic_read(&tg->ref) <= 0);
> + if (!atomic_dec_and_test(&tg->ref))
> + return;
> + kfree(tg);
> +}
> +
> +static struct throtl_grp * throtl_find_alloc_tg(struct throtl_data *td,
> + struct cgroup *cgroup)
> +{
> + struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
> + struct throtl_grp *tg = NULL;
> + void *key = td;
> + struct backing_dev_info *bdi = &td->queue->backing_dev_info;
> + unsigned int major, minor;
> +
> + /*
> + * TODO: Speed up blkiocg_lookup_group() by maintaining a radix
> + * tree of blkg (instead of traversing through hash list all
> + * the time.
> + */
> + tg = tg_of_blkg(blkiocg_lookup_group(blkcg, key));
> +
> + /* Fill in device details for root group */
> + if (tg && !tg->blkg.dev && bdi->dev && dev_name(bdi->dev)) {
> + sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
> + tg->blkg.dev = MKDEV(major, minor);
> + goto done;
> + }
> +
> + if (tg)
> + goto done;
> +
> + tg = kzalloc_node(sizeof(*tg), GFP_ATOMIC, td->queue->node);
> + if (!tg)
> + goto done;
> +
> + INIT_HLIST_NODE(&tg->tg_node);
> + RB_CLEAR_NODE(&tg->rb_node);
> + bio_list_init(&tg->bio_lists[0]);
> + bio_list_init(&tg->bio_lists[1]);
> +
> + /*
> + * Take the initial reference that will be released on destroy
> + * This can be thought of a joint reference by cgroup and
> + * request queue which will be dropped by either request queue
> + * exit or cgroup deletion path depending on who is exiting first.
> + */
> + atomic_set(&tg->ref, 1);
> +
> + /* Add group onto cgroup list */
> + sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
> + blkiocg_add_blkio_group(blkcg, &tg->blkg, (void *)td,
> + MKDEV(major, minor));
> +
> + tg->bps[READ] = blkcg_get_read_bps(blkcg, tg->blkg.dev);
> + tg->bps[WRITE] = blkcg_get_write_bps(blkcg, tg->blkg.dev);
> +
> + hlist_add_head(&tg->tg_node, &td->tg_list);
> + td->nr_undestroyed_grps++;
> +done:
> + return tg;
> +}
> +
> +static struct throtl_grp * throtl_get_tg(struct throtl_data *td)
> +{
> + struct cgroup *cgroup;
> + struct throtl_grp *tg = NULL;
> +
> + rcu_read_lock();
> + cgroup = task_cgroup(current, blkio_subsys_id);
> + tg = throtl_find_alloc_tg(td, cgroup);
> + if (!tg)
> + tg = &td->root_tg;
> + rcu_read_unlock();
> + return tg;
> +}
> +
> +static struct throtl_grp *throtl_rb_first(struct throtl_rb_root *root)
> +{
> + /* Service tree is empty */
> + if (!root->count)
> + return NULL;
> +
> + if (!root->left)
> + root->left = rb_first(&root->rb);
> +
> + if (root->left)
> + return rb_entry_tg(root->left);
> +
> + return NULL;
> +}
> +
> +static void rb_erase_init(struct rb_node *n, struct rb_root *root)
> +{
> + rb_erase(n, root);
> + RB_CLEAR_NODE(n);
> +}
> +
> +static void throtl_rb_erase(struct rb_node *n, struct throtl_rb_root *root)
> +{
> + if (root->left == n)
> + root->left = NULL;
> + rb_erase_init(n, &root->rb);
> + --root->count;
> +}
> +
> +static void update_min_dispatch_time(struct throtl_rb_root *st)
> +{
> + struct throtl_grp *tg;
> +
> + tg = throtl_rb_first(st);
> + if (!tg)
> + return;
> +
> + st->min_disptime = tg->disptime;
> +}
> +
> +static void
> +tg_service_tree_add(struct throtl_rb_root *st, struct throtl_grp *tg)
> +{
> + struct rb_node **node = &st->rb.rb_node;
> + struct rb_node *parent = NULL;
> + struct throtl_grp *__tg;
> + unsigned long key = tg->disptime;
> + int left = 1;
> +
> + while (*node != NULL) {
> + parent = *node;
> + __tg = rb_entry_tg(parent);
> +
> + if (time_before(key, __tg->disptime))
> + node = &parent->rb_left;
> + else {
> + node = &parent->rb_right;
> + left = 0;
> + }
> + }
> +
> + if (left)
> + st->left = &tg->rb_node;
> +
> + rb_link_node(&tg->rb_node, parent, node);
> + rb_insert_color(&tg->rb_node, &st->rb);
> +}
> +
> +static void __throtl_enqueue_tg(struct throtl_data *td, struct throtl_grp *tg)
> +{
> + struct throtl_rb_root *st = &td->tg_service_tree;
> +
> + tg_service_tree_add(st, tg);
> + throtl_mark_tg_on_rr(tg);
> + st->count++;
> +}
> +
> +static void throtl_enqueue_tg(struct throtl_data *td, struct throtl_grp *tg)
> +{
> + if (!throtl_tg_on_rr(tg))
> + __throtl_enqueue_tg(td, tg);
> +}
> +
> +static void __throtl_dequeue_tg(struct throtl_data *td, struct throtl_grp *tg)
> +{
> + throtl_rb_erase(&tg->rb_node, &td->tg_service_tree);
> + throtl_clear_tg_on_rr(tg);
> +}
> +
> +static void throtl_dequeue_tg(struct throtl_data *td, struct throtl_grp *tg)
> +{
> + if (throtl_tg_on_rr(tg))
> + __throtl_dequeue_tg(td, tg);
> +}
> +
> +static void throtl_schedule_next_dispatch(struct throtl_data *td)
> +{
> + struct throtl_rb_root *st = &td->tg_service_tree;
> +
> + /*
> + * If there are more bios pending, schedule more work.
> + */
> + if (!total_nr_queued(td))
> + return;
> +
> + BUG_ON(!st->count);
> +
> + update_min_dispatch_time(st);
> +
> + if (time_before_eq(st->min_disptime, jiffies))
> + throtl_schedule_delayed_work(td->queue, 0);
> + else
> + throtl_schedule_delayed_work(td->queue,
> + (st->min_disptime - jiffies));
> +}
> +
> +static inline void
> +throtl_start_new_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw)
> +{
> + tg->bytes_disp[rw] = 0;
> + tg->slice_start[rw] = jiffies;
> + tg->slice_end[rw] = jiffies + throtl_slice;
> + throtl_log_tg(td, tg, "[%c] new slice start=%lu end=%lu jiffies=%lu",
> + rw == READ ? 'R' : 'W', tg->slice_start[rw],
> + tg->slice_end[rw], jiffies);
> +}
> +
> +static inline void throtl_extend_slice(struct throtl_data *td,
> + struct throtl_grp *tg, bool rw, unsigned long jiffy_end)
> +{
> + tg->slice_end[rw] = roundup(jiffy_end, throtl_slice);
> + throtl_log_tg(td, tg, "[%c] extend slice start=%lu end=%lu jiffies=%lu",
> + rw == READ ? 'R' : 'W', tg->slice_start[rw],
> + tg->slice_end[rw], jiffies);
> +}
> +
> +/* Trim the used slices and adjust slice start accordingly */
> +static inline void
> +throtl_trim_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw)
> +{
> + unsigned long nr_slices, bytes_trim, time_elapsed;
> +
> + BUG_ON(time_before(tg->slice_end[rw], tg->slice_start[rw]));
> +
> + time_elapsed = jiffies - tg->slice_start[rw];
> +
> + nr_slices = time_elapsed / throtl_slice;
> +
> + if (!nr_slices)
> + return;
> +
> + bytes_trim = (tg->bps[rw] * throtl_slice * nr_slices)/HZ;
> +
> + if (!bytes_trim)
> + return;
> +
> + if (tg->bytes_disp[rw] >= bytes_trim)
> + tg->bytes_disp[rw] -= bytes_trim;
> + else
> + tg->bytes_disp[rw] = 0;
> +
> + tg->slice_start[rw] += nr_slices * throtl_slice;
> +
> + throtl_log_tg(td, tg, "[%c] trim slice nr=%lu bytes=%lu"
> + " start=%lu end=%lu jiffies=%lu",
> + rw == READ ? 'R' : 'W', nr_slices, bytes_trim,
> + tg->slice_start[rw], tg->slice_end[rw], jiffies);
> +}
> +
> +/* Determine if previously allocated or extended slice is complete or not */
> +static bool throtl_slice_used(struct throtl_data *td, struct throtl_grp *tg, bool rw)
> +{
> + if (time_in_range(jiffies, tg->slice_start[rw], tg->slice_end[rw]))
> + return 0;
> +
> + return 1;
> +}
> +
> +/*
> + * Returns whether one can dispatch a bio or not. Also returns approx number
> + * of jiffies to wait before this bio is with-in IO rate and can be dispatched
> + */
> +static bool tg_may_dispatch(struct throtl_data *td, struct throtl_grp *tg,
> + struct bio *bio, unsigned long *wait)
> +{
> + bool rw = bio_data_dir(bio);
> + u64 bytes_allowed, extra_bytes;
> + unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;
> +
> + /*
> + * Currently whole state machine of group depends on first bio
> + * queued in the group bio list. So one should not be calling
> + * this function with a different bio if there are other bios
> + * queued.
> + */
> + BUG_ON(tg->nr_queued[rw] && bio != bio_list_peek(&tg->bio_lists[rw]));
> +
> + /* If tg->bps = -1, then BW is unlimited */
> + if (tg->bps[rw] == -1)
> + return 1;
> +
> + /*
> + * If previous slice expired, start a new one otherwise renew/extend
> + * existing slice to make sure it is at least throtl_slice interval
> + * long since now.
> + */
> + if (throtl_slice_used(td, tg, rw))
> + throtl_start_new_slice(td, tg, rw);
> + else {
> + if (time_before(tg->slice_end[rw], jiffies + throtl_slice))
> + throtl_extend_slice(td, tg, rw, jiffies + throtl_slice);
> + }
> +
> + jiffy_elapsed = jiffy_elapsed_rnd = jiffies - tg->slice_start[rw];
> +
> + /* Slice has just started. Consider one slice interval */
> + if (!jiffy_elapsed)
> + jiffy_elapsed_rnd = throtl_slice;
> +
> + jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, throtl_slice);
> +
> + bytes_allowed = (tg->bps[rw] * jiffies_to_msecs(jiffy_elapsed_rnd))
> + / MSEC_PER_SEC;
> +
> + if (tg->bytes_disp[rw] + bio->bi_size <= bytes_allowed) {
> + if (wait)
> + *wait = 0;
> + return 1;
> + }
> +
> + /* Calc approx time to dispatch */
> + extra_bytes = tg->bytes_disp[rw] + bio->bi_size - bytes_allowed;
> + jiffy_wait = div64_u64(extra_bytes * HZ, tg->bps[rw]);
> +
> + if (!jiffy_wait)
> + jiffy_wait = 1;
> +
> + /*
> + * This wait time is without taking into consideration the rounding
> + * up we did. Add that time also.
> + */
> + jiffy_wait = jiffy_wait + (jiffy_elapsed_rnd - jiffy_elapsed);
> +
> + if (wait)
> + *wait = jiffy_wait;
> +
> + if (time_before(tg->slice_end[rw], jiffies + jiffy_wait))
> + throtl_extend_slice(td, tg, rw, jiffies + jiffy_wait);
> +
> + return 0;
> +}
> +
> +static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio)
> +{
> + bool rw = bio_data_dir(bio);
> +
> + /* Charge the bio to the group */
> + tg->bytes_disp[rw] += bio->bi_size;
> +
> +}
> +
> +static void throtl_add_bio_tg(struct throtl_data *td, struct throtl_grp *tg,
> + struct bio *bio)
> +{
> + bool rw = bio_data_dir(bio);
> +
> + bio_list_add(&tg->bio_lists[rw], bio);
> + /* Take a bio reference on tg */
> + throtl_ref_get_tg(tg);
> + tg->nr_queued[rw]++;
> + td->nr_queued[rw]++;
> + throtl_enqueue_tg(td, tg);
> +}
> +
> +static void tg_update_disptime(struct throtl_data *td, struct throtl_grp *tg)
> +{
> + unsigned long read_wait = -1, write_wait = -1, min_wait = -1, disptime;
> + struct bio *bio;
> +
> + if ((bio = bio_list_peek(&tg->bio_lists[READ])))
> + tg_may_dispatch(td, tg, bio, &read_wait);
> +
> + if ((bio = bio_list_peek(&tg->bio_lists[WRITE])))
> + tg_may_dispatch(td, tg, bio, &write_wait);
> +
> + min_wait = min(read_wait, write_wait);
> + disptime = jiffies + min_wait;
> +
> + /*
> + * If group is already on active tree, then update dispatch time
> + * only if it is lesser than existing dispatch time. Otherwise
> + * always update the dispatch time
> + */
> +
> + if (throtl_tg_on_rr(tg) && time_before(disptime, tg->disptime))
> + return;
> +
> + /* Update dispatch time */
> + throtl_dequeue_tg(td, tg);
> + tg->disptime = disptime;
> + throtl_enqueue_tg(td, tg);
> +}
> +
> +static void
> +tg_dispatch_one_bio(struct throtl_data *td, struct throtl_grp *tg, bool rw)
> +{
> + struct bio *bio;
> +
> + bio = bio_list_pop(&tg->bio_lists[rw]);
> + tg->nr_queued[rw]--;
> + /* Drop bio reference on tg */
> + throtl_put_tg(tg);
> +
> + BUG_ON(td->nr_queued[rw] <= 0);
> + td->nr_queued[rw]--;
> +
> + throtl_charge_bio(tg, bio);
> + bio_list_add(&td->disp_list, bio);
> + td->nr_disp_list++;
> +
> + throtl_trim_slice(td, tg, rw);
> +}
> +
> +/*
> + * Enter with queue lock held spin_lock_irq(). Returns with queue lock unlocked */
> +static int release_from_disp_list(struct throtl_data *td)
> +{
> + struct bio *bio;
> + unsigned int nr_disp = 0;
> +
> + if (!td->nr_disp_list)
> + goto out;
> +
> + while (!bio_list_empty(&td->disp_list)) {
> + bio = bio_list_pop(&td->disp_list);
> + bio->bi_rw |= REQ_THROTTLED;
> + BUG_ON(td->nr_disp_list <= 0);
> + td->nr_disp_list--;
> + nr_disp++;
> + /*
> + * Drop the spin lock as bio submission to request queue
> + * might sleep while getting request descriptor
> + */
> + spin_unlock_irq(td->queue->queue_lock);
> + td->queue->make_request_fn(td->queue, bio);
> + spin_lock_irq(td->queue->queue_lock);
> + }
> +
> +out:
> + spin_unlock_irq(td->queue->queue_lock);
> + return nr_disp;
> +}
> +
> +static int throtl_dispatch_tg(struct throtl_data *td, struct throtl_grp *tg)
> +{
> + unsigned int nr_reads = 0, nr_writes = 0;
> + unsigned int max_nr_reads = throtl_grp_quantum*3/4;
> + unsigned int max_nr_writes = throtl_grp_quantum - nr_reads;
> + struct bio *bio;
> +
> + /* Try to dispatch 75% READS and 25% WRITES */
> +
> + while ((bio = bio_list_peek(&tg->bio_lists[READ]))
> + && tg_may_dispatch(td, tg, bio, NULL)) {
> +
> + tg_dispatch_one_bio(td, tg, bio_data_dir(bio));
> + nr_reads++;
> +
> + if (nr_reads >= max_nr_reads)
> + break;
> + }
> +
> + while ((bio = bio_list_peek(&tg->bio_lists[WRITE]))
> + && tg_may_dispatch(td, tg, bio, NULL)) {
> +
> + tg_dispatch_one_bio(td, tg, bio_data_dir(bio));
> + nr_writes++;
> +
> + if (nr_writes >= max_nr_writes)
> + break;
> + }
> +
> + return nr_reads + nr_writes;
> +}
> +
> +static int throtl_select_dispatch(struct throtl_data *td)
> +{
> + unsigned int nr_disp = 0;
> + struct throtl_grp *tg;
> + struct throtl_rb_root *st = &td->tg_service_tree;
> +
> + while (1) {
> + tg = throtl_rb_first(st);
> +
> + if (!tg)
> + break;
> +
> + if (time_before(jiffies, tg->disptime))
> + break;
> +
> + throtl_dequeue_tg(td, tg);
> +
> + nr_disp += throtl_dispatch_tg(td, tg);
> +
> + if (tg->nr_queued[0] || tg->nr_queued[1]) {
> + tg_update_disptime(td, tg);
> + throtl_enqueue_tg(td, tg);
> + }
> +
> + if (nr_disp >= throtl_quantum)
> + break;
> + }
> +
> + return nr_disp;
> +}
> +
> +/* Dispatch throttled bios. Should be called without queue lock held. */
> +static int throtl_dispatch(struct request_queue *q)
> +{
> + struct throtl_data *td = q->td;
> + unsigned int nr_disp = 0, temp_disp = 0;
> +
> + spin_lock_irq(q->queue_lock);
> +
> + throtl_log(td, "dispatch nr_queued=%lu", total_nr_queued(td));
> +
> + if (!total_nr_queued(td))
> + goto out;
> +
> + while(1) {
> + temp_disp = 0;
> + temp_disp = release_from_disp_list(q->td);
> + nr_disp += temp_disp;
> +
> + if (nr_disp >= throtl_quantum)
> + break;
> +
> + /*
> + * release_from_disp_list returns with queue lock unlocked.
> + * acquire the lock again.
> + */
> + spin_lock_irq(q->queue_lock);
> + temp_disp = throtl_select_dispatch(td);
> + if (!temp_disp)
> + break;
> + }
> +
> + throtl_schedule_next_dispatch(td);
> +out:
> + spin_unlock_irq(q->queue_lock);
> + /*
> + * If we dispatched some requests, unplug the queue to make sure
> + * immediate dispatch
> + */
> + if (nr_disp) {
> + throtl_log(td, "bios disp=%u", nr_disp);
> + blk_unplug(q);
> + }
> + return nr_disp;
> +}
> +
> +void blk_throtl_work(struct work_struct *work)
> +{
> + struct throtl_data *td = container_of(work, struct throtl_data,
> + throtl_work.work);
> + struct request_queue *q = td->queue;
> +
> + throtl_dispatch(q);
> +}
> +
> +/* Call with queue lock held */
> +void throtl_schedule_delayed_work(struct request_queue *q, unsigned long delay)
> +{
> +
> + struct throtl_data *td = q->td;
> + struct delayed_work *dwork = &td->throtl_work;
> +
> + if (total_nr_queued(td) > 0) {
> + /*
> + * We might have a work scheduled to be executed in future.
> + * Cancel that and schedule a new one.
> + */
> + __cancel_delayed_work(dwork);
> + kblockd_schedule_delayed_work(q, dwork, delay);
> + throtl_log(td, "schedule work. delay=%lu jiffies=%lu",
> + delay, jiffies);
> + }
> +}
> +EXPORT_SYMBOL(throtl_schedule_delayed_work);
> +
> +static void
> +throtl_destroy_tg(struct throtl_data *td, struct throtl_grp *tg)
> +{
> + /* Something wrong if we are trying to remove same group twice */
> + BUG_ON(hlist_unhashed(&tg->tg_node));
> +
> + hlist_del_init(&tg->tg_node);
> +
> + /*
> + * Put the reference taken at the time of creation so that when all
> + * queues are gone, group can be destroyed.
> + */
> + throtl_put_tg(tg);
> + td->nr_undestroyed_grps--;
> +}
> +
> +static void throtl_release_tgs(struct throtl_data *td)
> +{
> + struct hlist_node *pos, *n;
> + struct throtl_grp *tg;
> +
> + hlist_for_each_entry_safe(tg, pos, n, &td->tg_list, tg_node) {
> + /*
> + * If cgroup removal path got to blk_group first and removed
> + * it from cgroup list, then it will take care of destroying
> + * cfqg also.
> + */
> + if (!blkiocg_del_blkio_group(&tg->blkg))
> + throtl_destroy_tg(td, tg);
> + }
> +}
> +
> +static void throtl_td_free(struct throtl_data *td)
> +{
> + kfree(td);
> +}
> +
> +/*
> + * Blk cgroup controller notification saying that blkio_group object is being
> + * delinked as associated cgroup object is going away. That also means that
> + * no new IO will come in this group. So get rid of this group as soon as
> + * any pending IO in the group is finished.
> + *
> + * This function is called under rcu_read_lock(). key is the rcu protected
> + * pointer. That means "key" is a valid throtl_data pointer as long as we are
> + * rcu read lock.
> + *
> + * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
> + * it should not be NULL as even if queue was going away, cgroup deltion
> + * path got to it first.
> + */
> +void throtl_unlink_blkio_group(void *key, struct blkio_group *blkg)
> +{
> + unsigned long flags;
> + struct throtl_data *td = key;
> +
> + spin_lock_irqsave(td->queue->queue_lock, flags);
> + throtl_destroy_tg(td, tg_of_blkg(blkg));
> + spin_unlock_irqrestore(td->queue->queue_lock, flags);
> +}
> +
> +static void throtl_update_blkio_group_read_bps (struct blkio_group *blkg,
> + u64 read_bps)
> +{
> + tg_of_blkg(blkg)->bps[READ] = read_bps;
> +}
> +
> +static void throtl_update_blkio_group_write_bps (struct blkio_group *blkg,
> + u64 write_bps)
> +{
> + tg_of_blkg(blkg)->bps[WRITE] = write_bps;
> +}
> +
> +void throtl_shutdown_timer_wq(struct request_queue *q)
> +{
> + struct throtl_data *td = q->td;
> +
> + cancel_delayed_work_sync(&td->throtl_work);
> +}
> +
> +static struct blkio_policy_type blkio_policy_throtl = {
> + .ops = {
> + .blkio_unlink_group_fn = throtl_unlink_blkio_group,
> + .blkio_update_group_read_bps_fn =
> + throtl_update_blkio_group_read_bps,
> + .blkio_update_group_write_bps_fn =
> + throtl_update_blkio_group_write_bps,
> + },
> +};
> +
> +int blk_throtl_bio(struct request_queue *q, struct bio **biop)
> +{
> + struct throtl_data *td = q->td;
> + struct throtl_grp *tg;
> + struct bio *bio = *biop;
> + bool rw = bio_data_dir(bio), update_disptime = true;
> +
> + if (bio->bi_rw & REQ_THROTTLED) {
> + bio->bi_rw &= ~REQ_THROTTLED;
> + return 0;
> + }
> +
> + tg = throtl_get_tg(td);
> +
> + if (tg->nr_queued[rw]) {
> + /*
> + * There is already another bio queued in same dir. No
> + * need to update dispatch time.
> + */
> + update_disptime = false;
> + goto queue_bio;
> + }
> +
> + /* Bio is with-in rate limit of group */
> + if (tg_may_dispatch(td, tg, bio, NULL)) {
> + throtl_charge_bio(tg, bio);
> + return 0;
> + }
> +
> +queue_bio:
> + throtl_log_tg(td, tg, "[%c] bio. disp=%u sz=%u bps=%llu"
> + " queued=%d/%d", rw == READ ? 'R' : 'W',
> + tg->bytes_disp[rw], bio->bi_size, tg->bps[rw],
> + tg->nr_queued[READ], tg->nr_queued[WRITE]);
> +
> + throtl_add_bio_tg(q->td, tg, bio);
> + *biop = NULL;
> +
> + if (update_disptime) {
> + tg_update_disptime(td, tg);
> + throtl_schedule_next_dispatch(td);
> + }
> +
> + return 0;
> +}
> +
> +int blk_throtl_init(struct request_queue *q)
> +{
> + struct throtl_data *td;
> + struct throtl_grp *tg;
> +
> + td = kzalloc_node(sizeof(*td), GFP_KERNEL, q->node);
> + if (!td)
> + return -ENOMEM;
> +
> + INIT_HLIST_HEAD(&td->tg_list);
> + td->tg_service_tree = THROTL_RB_ROOT;
> + bio_list_init(&td->disp_list);
> +
> + /* Init root group */
> + tg = &td->root_tg;
> + INIT_HLIST_NODE(&tg->tg_node);
> + RB_CLEAR_NODE(&tg->rb_node);
> + bio_list_init(&tg->bio_lists[0]);
> + bio_list_init(&tg->bio_lists[1]);
> +
> + /* Practically unlimited BW */
> + tg->bps[0] = tg->bps[1] = -1;
> + atomic_set(&tg->ref, 1);
> +
> + INIT_DELAYED_WORK(&td->throtl_work, blk_throtl_work);
> +
> + rcu_read_lock();
> + blkiocg_add_blkio_group(&blkio_root_cgroup, &tg->blkg, (void *)td,
> + 0);
> + rcu_read_unlock();
> +
> + /* Attach throtl data to request queue */
> + td->queue = q;
> + q->td = td;
> + return 0;
> +}
> +
> +void blk_throtl_exit(struct request_queue *q)
> +{
> + struct throtl_data *td = q->td;
> + bool wait = false;
> +
> + BUG_ON(!td);
> +
> + throtl_shutdown_timer_wq(q);
> +
> + spin_lock_irq(q->queue_lock);
> + throtl_release_tgs(td);
> + blkiocg_del_blkio_group(&td->root_tg.blkg);
> +
> + /* If there are other groups */
> + if (td->nr_undestroyed_grps >= 1)
> + wait = true;
> +
> + spin_unlock_irq(q->queue_lock);
> +
> + /*
> + * Wait for tg->blkg->key accessors to exit their grace periods.
> + * Do this wait only if there are other undestroyed groups out
> + * there (other than root group). This can happen if cgroup deletion
> + * path claimed the responsibility of cleaning up a group before
> + * queue cleanup code get to the group.
> + *
> + * Do not call synchronize_rcu() unconditionally as there are drivers
> + * which create/delete request queue hundreds of times during scan/boot
> + * and synchronize_rcu() can take significant time and slow down boot.
> + */
> + if (wait)
> + synchronize_rcu();
> + throtl_td_free(td);
> +}
> +
> +static int __init throtl_init(void)
> +{
> + blkio_policy_register(&blkio_policy_throtl);
> + return 0;
> +}
> +
> +module_init(throtl_init);
> Index: linux-2.6/block/blk-cgroup.c
> ===================================================================
> --- linux-2.6.orig/block/blk-cgroup.c 2010-09-01 10:54:53.000000000 -0400
> +++ linux-2.6/block/blk-cgroup.c 2010-09-01 10:56:56.000000000 -0400
> @@ -67,12 +67,13 @@ static inline void blkio_policy_delete_n
>
> /* Must be called with blkcg->lock held */
> static struct blkio_policy_node *
> -blkio_policy_search_node(const struct blkio_cgroup *blkcg, dev_t dev)
> +blkio_policy_search_node(const struct blkio_cgroup *blkcg, dev_t dev,
> + enum blkio_policy_name pname, enum blkio_rule_type rulet)
> {
> struct blkio_policy_node *pn;
>
> list_for_each_entry(pn, &blkcg->policy_list, node) {
> - if (pn->dev == dev)
> + if (pn->dev == dev && pn->pname == pname && pn->rulet == rulet)
> return pn;
> }
>
> @@ -86,6 +87,34 @@ struct blkio_cgroup *cgroup_to_blkio_cgr
> }
> EXPORT_SYMBOL_GPL(cgroup_to_blkio_cgroup);
>
> +static inline void
> +blkio_update_group_weight(struct blkio_group *blkg, unsigned int weight)
> +{
> + struct blkio_policy_type *blkiop;
> +
> + list_for_each_entry(blkiop, &blkio_list, list) {
> + if (blkiop->ops.blkio_update_group_weight_fn)
> + blkiop->ops.blkio_update_group_weight_fn(blkg, weight);
> + }
> +}
> +
> +static inline void blkio_update_group_bps(struct blkio_group *blkg, u64 bps,
> + enum blkio_rule_type rulet)
> +{
> + struct blkio_policy_type *blkiop;
> +
> + list_for_each_entry(blkiop, &blkio_list, list) {
> + if (rulet == BLKIO_RULE_READ
> + && blkiop->ops.blkio_update_group_read_bps_fn)
> + blkiop->ops.blkio_update_group_read_bps_fn(blkg, bps);
> +
> + if (rulet == BLKIO_RULE_WRITE
> + && blkiop->ops.blkio_update_group_write_bps_fn)
> + blkiop->ops.blkio_update_group_write_bps_fn(blkg, bps);
> + }
> +}
> +
> +
> /*
> * Add to the appropriate stat variable depending on the request type.
> * This should be called with the blkg->stats_lock held.
> @@ -427,7 +456,6 @@ blkiocg_weight_write(struct cgroup *cgro
> struct blkio_cgroup *blkcg;
> struct blkio_group *blkg;
> struct hlist_node *n;
> - struct blkio_policy_type *blkiop;
> struct blkio_policy_node *pn;
>
> if (val < BLKIO_WEIGHT_MIN || val > BLKIO_WEIGHT_MAX)
> @@ -439,14 +467,12 @@ blkiocg_weight_write(struct cgroup *cgro
> blkcg->weight = (unsigned int)val;
>
> hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
> - pn = blkio_policy_search_node(blkcg, blkg->dev);
> -
> + pn = blkio_policy_search_node(blkcg, blkg->dev,
> + BLKIO_POLICY_PROP, BLKIO_RULE_WEIGHT);
> if (pn)
> continue;
>
> - list_for_each_entry(blkiop, &blkio_list, list)
> - blkiop->ops.blkio_update_group_weight_fn(blkg,
> - blkcg->weight);
> + blkio_update_group_weight(blkg, blkcg->weight);
> }
> spin_unlock_irq(&blkcg->lock);
> spin_unlock(&blkio_list_lock);
> @@ -652,11 +678,13 @@ static int blkio_check_dev_num(dev_t dev
> }
>
> static int blkio_policy_parse_and_set(char *buf,
> - struct blkio_policy_node *newpn)
> + struct blkio_policy_node *newpn, enum blkio_policy_name pname,
> + enum blkio_rule_type rulet)
> {
> char *s[4], *p, *major_s = NULL, *minor_s = NULL;
> int ret;
> unsigned long major, minor, temp;
> + u64 bps;
> int i = 0;
> dev_t dev;
>
> @@ -705,12 +733,27 @@ static int blkio_policy_parse_and_set(ch
> if (s[1] == NULL)
> return -EINVAL;
>
> - ret = strict_strtoul(s[1], 10, &temp);
> - if (ret || (temp < BLKIO_WEIGHT_MIN && temp > 0) ||
> - temp > BLKIO_WEIGHT_MAX)
> - return -EINVAL;
> + switch (pname) {
> + case BLKIO_POLICY_PROP:
> + ret = strict_strtoul(s[1], 10, &temp);
> + if (ret || (temp < BLKIO_WEIGHT_MIN && temp > 0) ||
> + temp > BLKIO_WEIGHT_MAX)
> + return -EINVAL;
> +
> + newpn->pname = pname;
> + newpn->rulet = rulet;
> + newpn->val.weight = temp;
> + break;
>
> - newpn->weight = temp;
> + case BLKIO_POLICY_THROTL:
> + ret = strict_strtoull(s[1], 10, &bps);
> + if (ret)
> + return -EINVAL;
> +
> + newpn->pname = pname;
> + newpn->rulet = rulet;
> + newpn->val.bps = bps;
> + }
>
> return 0;
> }
> @@ -720,26 +763,121 @@ unsigned int blkcg_get_weight(struct blk
> {
> struct blkio_policy_node *pn;
>
> - pn = blkio_policy_search_node(blkcg, dev);
> + pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_PROP,
> + BLKIO_RULE_WEIGHT);
> if (pn)
> - return pn->weight;
> + return pn->val.weight;
> else
> return blkcg->weight;
> }
> EXPORT_SYMBOL_GPL(blkcg_get_weight);
>
> +uint64_t blkcg_get_read_bps(struct blkio_cgroup *blkcg, dev_t dev)
> +{
> + struct blkio_policy_node *pn;
> +
> + pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
> + BLKIO_RULE_READ);
> + if (pn)
> + return pn->val.bps;
> + else
> + return -1;
> +}
> +EXPORT_SYMBOL_GPL(blkcg_get_read_bps);
> +
> +uint64_t blkcg_get_write_bps(struct blkio_cgroup *blkcg, dev_t dev)
> +{
> + struct blkio_policy_node *pn;
> +
> + pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
> + BLKIO_RULE_WRITE);
> + if (pn)
> + return pn->val.bps;
> + else
> + return -1;
> +}
> +EXPORT_SYMBOL_GPL(blkcg_get_write_bps);
> +
> +/* Checks whether user asked for deleting a policy rule */
> +static bool blkio_delete_rule_command(struct blkio_policy_node *pn)
> +{
> + switch(pn->pname) {
> + case BLKIO_POLICY_PROP:
> + if (pn->val.weight == 0)
> + return 1;
> + break;
> + case BLKIO_POLICY_THROTL:
> + if (pn->val.bps == 0)
> + return 1;
> + break;
> + default:
> + BUG();
> + }
> +
> + return 0;
> +}
> +
> +static void blkio_update_policy_rule(struct blkio_policy_node *oldpn,
> + struct blkio_policy_node *newpn)
> +{
> + switch(oldpn->pname) {
> + case BLKIO_POLICY_PROP:
> + oldpn->val.weight = newpn->val.weight;
> + break;
> + case BLKIO_POLICY_THROTL:
> + oldpn->val.bps = newpn->val.bps;
> + break;
> + default:
> + BUG();
> + }
> +}
> +
> +/*
> + * A policy node rule has been updated. Propogate this update to all the
> + * block groups which might be affected by this update.
> + */
> +static void blkio_update_policy_node_blkg(struct blkio_cgroup *blkcg,
> + struct blkio_policy_node *pn)
> +{
> + struct blkio_group *blkg;
> + struct hlist_node *n;
> + enum blkio_rule_type rulet = pn->rulet;
> + unsigned int weight;
> + u64 bps;
>
> -static int blkiocg_weight_device_write(struct cgroup *cgrp, struct cftype *cft,
> + spin_lock(&blkio_list_lock);
> + spin_lock_irq(&blkcg->lock);
> +
> + hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
> + if (pn->dev == blkg->dev) {
> + if (pn->pname == BLKIO_POLICY_PROP) {
> + weight = pn->val.weight ? pn->val.weight :
> + blkcg->weight;
> + blkio_update_group_weight(blkg, weight);
> + } else {
> +
> + bps = pn->val.bps ? pn->val.bps : (-1);
> + blkio_update_group_bps(blkg, bps, rulet);
> + }
> + }
> + }
> +
> + spin_unlock_irq(&blkcg->lock);
> + spin_unlock(&blkio_list_lock);
> +
> +}
> +
> +static int blkiocg_file_write(struct cgroup *cgrp, struct cftype *cft,
> const char *buffer)
> {
> int ret = 0;
> char *buf;
> struct blkio_policy_node *newpn, *pn;
> struct blkio_cgroup *blkcg;
> - struct blkio_group *blkg;
> int keep_newpn = 0;
> - struct hlist_node *n;
> - struct blkio_policy_type *blkiop;
> + int name = cft->private;
> + enum blkio_policy_name pname;
> + enum blkio_rule_type rulet;
>
> buf = kstrdup(buffer, GFP_KERNEL);
> if (!buf)
> @@ -751,7 +889,26 @@ static int blkiocg_weight_device_write(s
> goto free_buf;
> }
>
> - ret = blkio_policy_parse_and_set(buf, newpn);
> + switch (name) {
> + case BLKIO_FILE_weight_device:
> + pname = BLKIO_POLICY_PROP;
> + rulet = BLKIO_RULE_WEIGHT;
> + ret = blkio_policy_parse_and_set(buf, newpn, pname, 0);
> + break;
> + case BLKIO_FILE_read_bps_device:
> + pname = BLKIO_POLICY_THROTL;
> + rulet = BLKIO_RULE_READ;
> + ret = blkio_policy_parse_and_set(buf, newpn, pname, rulet);
> + break;
> + case BLKIO_FILE_write_bps_device:
> + pname = BLKIO_POLICY_THROTL;
> + rulet = BLKIO_RULE_WRITE;
> + ret = blkio_policy_parse_and_set(buf, newpn, pname, rulet);
> + break;
> + default:
> + BUG();
> + }
> +
> if (ret)
> goto free_newpn;
>
> @@ -759,9 +916,10 @@ static int blkiocg_weight_device_write(s
>
> spin_lock_irq(&blkcg->lock);
>
> - pn = blkio_policy_search_node(blkcg, newpn->dev);
> + pn = blkio_policy_search_node(blkcg, newpn->dev, pname, rulet);
> +
> if (!pn) {
> - if (newpn->weight != 0) {
> + if (!blkio_delete_rule_command(newpn)) {
> blkio_policy_insert_node(blkcg, newpn);
> keep_newpn = 1;
> }
> @@ -769,56 +927,61 @@ static int blkiocg_weight_device_write(s
> goto update_io_group;
> }
>
> - if (newpn->weight == 0) {
> - /* weight == 0 means deleteing a specific weight */
> + if (blkio_delete_rule_command(newpn)) {
> blkio_policy_delete_node(pn);
> spin_unlock_irq(&blkcg->lock);
> goto update_io_group;
> }
> spin_unlock_irq(&blkcg->lock);
>
> - pn->weight = newpn->weight;
> + blkio_update_policy_rule(pn, newpn);
>
> update_io_group:
> - /* update weight for each cfqg */
> - spin_lock(&blkio_list_lock);
> - spin_lock_irq(&blkcg->lock);
> -
> - hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
> - if (newpn->dev == blkg->dev) {
> - list_for_each_entry(blkiop, &blkio_list, list)
> - blkiop->ops.blkio_update_group_weight_fn(blkg,
> - newpn->weight ?
> - newpn->weight :
> - blkcg->weight);
> - }
> - }
> -
> - spin_unlock_irq(&blkcg->lock);
> - spin_unlock(&blkio_list_lock);
> -
> + blkio_update_policy_node_blkg(blkcg, newpn);
> free_newpn:
> if (!keep_newpn)
> kfree(newpn);
> free_buf:
> kfree(buf);
> +
> return ret;
> }
>
> -static int blkiocg_weight_device_read(struct cgroup *cgrp, struct cftype *cft,
> - struct seq_file *m)
> +
> +static int blkiocg_file_read(struct cgroup *cgrp, struct cftype *cft,
> + struct seq_file *m)
> {
> + int name = cft->private;
> struct blkio_cgroup *blkcg;
> struct blkio_policy_node *pn;
>
> - seq_printf(m, "dev\tweight\n");
> -
> blkcg = cgroup_to_blkio_cgroup(cgrp);
> +
> if (!list_empty(&blkcg->policy_list)) {
> spin_lock_irq(&blkcg->lock);
> list_for_each_entry(pn, &blkcg->policy_list, node) {
> - seq_printf(m, "%u:%u\t%u\n", MAJOR(pn->dev),
> - MINOR(pn->dev), pn->weight);
> + switch(name) {
> + case BLKIO_FILE_weight_device:
> + if (pn->pname != BLKIO_POLICY_PROP)
> + continue;
> + seq_printf(m, "%u:%u\t%u\n", MAJOR(pn->dev),
> + MINOR(pn->dev), pn->val.weight);
> + break;
> + case BLKIO_FILE_read_bps_device:
> + if (pn->pname != BLKIO_POLICY_THROTL
> + || pn->rulet != BLKIO_RULE_READ)
> + continue;
> + seq_printf(m, "%u:%u\t%llu\n", MAJOR(pn->dev),
> + MINOR(pn->dev), pn->val.bps);
> + break;
> + case BLKIO_FILE_write_bps_device:
> + if (pn->pname != BLKIO_POLICY_THROTL
> + || pn->rulet != BLKIO_RULE_WRITE)
> + continue;
> + seq_printf(m, "%u:%u\t%llu\n", MAJOR(pn->dev),
> + MINOR(pn->dev), pn->val.bps);
> + break;
> + }
> }
> spin_unlock_irq(&blkcg->lock);
> }
> @@ -829,8 +992,9 @@ static int blkiocg_weight_device_read(st
> struct cftype blkio_files[] = {
> {
> .name = "weight_device",
> - .read_seq_string = blkiocg_weight_device_read,
> - .write_string = blkiocg_weight_device_write,
> + .private = BLKIO_FILE_weight_device,
> + .read_seq_string = blkiocg_file_read,
> + .write_string = blkiocg_file_write,
> .max_write_len = 256,
> },
> {
> @@ -838,6 +1002,22 @@ struct cftype blkio_files[] = {
> .read_u64 = blkiocg_weight_read,
> .write_u64 = blkiocg_weight_write,
> },
> +
> + {
> + .name = "read_bps_device",
> + .private = BLKIO_FILE_read_bps_device,
> + .read_seq_string = blkiocg_file_read,
> + .write_string = blkiocg_file_write,
> + .max_write_len = 256,
> + },
> +
> + {
> + .name = "write_bps_device",
> + .private = BLKIO_FILE_write_bps_device,
> + .read_seq_string = blkiocg_file_read,
> + .write_string = blkiocg_file_write,
> + .max_write_len = 256,
> + },
> {
> .name = "time",
> .read_map = blkiocg_time_read,
> Index: linux-2.6/block/blk-cgroup.h
> ===================================================================
> --- linux-2.6.orig/block/blk-cgroup.h 2010-09-01 10:54:53.000000000 -0400
> +++ linux-2.6/block/blk-cgroup.h 2010-09-01 10:56:56.000000000 -0400
> @@ -65,6 +65,12 @@ enum blkg_state_flags {
> BLKG_empty,
> };
>
> +enum blkcg_file_name {
> + BLKIO_FILE_weight_device = 1,
> + BLKIO_FILE_read_bps_device,
> + BLKIO_FILE_write_bps_device,
> +};
> +
> struct blkio_cgroup {
> struct cgroup_subsys_state css;
> unsigned int weight;
> @@ -118,22 +124,58 @@ struct blkio_group {
> struct blkio_group_stats stats;
> };
>
> +enum blkio_policy_name {
> + BLKIO_POLICY_PROP = 0, /* Proportional Bandwidth division */
> + BLKIO_POLICY_THROTL, /* Throttling */
> +};
> +
> +enum blkio_rule_type {
> + BLKIO_RULE_WEIGHT = 0,
> + BLKIO_RULE_READ,
> + BLKIO_RULE_WRITE,
> +};
> +
> struct blkio_policy_node {
> struct list_head node;
> dev_t dev;
> - unsigned int weight;
> +
> + /* This node belongs to max bw policy or porportional weight policy */
> + enum blkio_policy_name pname;
> +
> + /* Whether a read or write rule */
> + enum blkio_rule_type rulet;
> +
> + union {
> + unsigned int weight;
> + /*
> + * Rate read/write in terms of byptes per second
> + * Whether this rate represents read or write is determined
> + * by rule type "rulet"
> + */
> + u64 bps;
> + } val;
> };
>
> extern unsigned int blkcg_get_weight(struct blkio_cgroup *blkcg,
> dev_t dev);
> +extern uint64_t blkcg_get_read_bps(struct blkio_cgroup *blkcg,
> + dev_t dev);
> +extern uint64_t blkcg_get_write_bps(struct blkio_cgroup *blkcg,
> + dev_t dev);
>
> typedef void (blkio_unlink_group_fn) (void *key, struct blkio_group *blkg);
> typedef void (blkio_update_group_weight_fn) (struct blkio_group *blkg,
> unsigned int weight);
> +typedef void (blkio_update_group_read_bps_fn) (struct blkio_group *blkg,
> + u64 read_bps);
> +typedef void (blkio_update_group_write_bps_fn) (struct blkio_group *blkg,
> + u64 write_bps);
>
> struct blkio_policy_ops {
> blkio_unlink_group_fn *blkio_unlink_group_fn;
> blkio_update_group_weight_fn *blkio_update_group_weight_fn;
> + blkio_update_group_read_bps_fn *blkio_update_group_read_bps_fn;
> + blkio_update_group_write_bps_fn *blkio_update_group_write_bps_fn;
> };
>
> struct blkio_policy_type {
> Index: linux-2.6/block/blk.h
> ===================================================================
> --- linux-2.6.orig/block/blk.h 2010-09-01 10:54:53.000000000 -0400
> +++ linux-2.6/block/blk.h 2010-09-01 10:56:56.000000000 -0400
> @@ -62,8 +62,10 @@ static inline struct request *__elv_next
> return rq;
> }
>
> - if (!q->elevator->ops->elevator_dispatch_fn(q, 0))
> + if (!q->elevator->ops->elevator_dispatch_fn(q, 0)) {
> + throtl_schedule_delayed_work(q, 0);
> return NULL;
> + }
> }
> }
>
> Index: linux-2.6/block/cfq-iosched.c
> ===================================================================
> --- linux-2.6.orig/block/cfq-iosched.c 2010-09-01 10:54:53.000000000 -0400
> +++ linux-2.6/block/cfq-iosched.c 2010-09-01 10:56:56.000000000 -0400
> @@ -467,10 +467,14 @@ static inline bool cfq_bio_sync(struct b
> */
> static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
> {
> + struct request_queue *q = cfqd->queue;
> +
> if (cfqd->busy_queues) {
> cfq_log(cfqd, "schedule dispatch");
> kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
> }
> +
> + throtl_schedule_delayed_work(q, 0);
> }
>
> static int cfq_queue_empty(struct request_queue *q)
> Index: linux-2.6/include/linux/blk_types.h
> ===================================================================
> --- linux-2.6.orig/include/linux/blk_types.h 2010-09-01 10:54:53.000000000 -0400
> +++ linux-2.6/include/linux/blk_types.h 2010-09-01 10:56:56.000000000 -0400
> @@ -130,6 +130,8 @@ enum rq_flag_bits {
> /* bio only flags */
> __REQ_UNPLUG, /* unplug the immediately after submission */
> __REQ_RAHEAD, /* read ahead, can fail anytime */
> + __REQ_THROTTLED, /* This bio has already been subjected to
> + * throttling rules. Don't do it again. */
>
> /* request only flags */
> __REQ_SORTED, /* elevator knows about this request */
> @@ -172,6 +174,7 @@ enum rq_flag_bits {
>
> #define REQ_UNPLUG (1 << __REQ_UNPLUG)
> #define REQ_RAHEAD (1 << __REQ_RAHEAD)
> +#define REQ_THROTTLED (1 << __REQ_THROTTLED)
>
> #define REQ_SORTED (1 << __REQ_SORTED)
> #define REQ_SOFTBARRIER (1 << __REQ_SOFTBARRIER)
>
>
--
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