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Commit 6c510389 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block 

* 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block: (65 commits)
  Documentation/iostats.txt: bit-size reference etc.
  cfq-iosched: removing unnecessary think time checking
  cfq-iosched: Don't clear queue stats when preempt.
  blk-throttle: Reset group slice when limits are changed
  blk-cgroup: Only give unaccounted_time under debug
  cfq-iosched: Don't set active queue in preempt
  block: fix non-atomic access to genhd inflight structures
  block: attempt to merge with existing requests on plug flush
  block: NULL dereference on error path in __blkdev_get()
  cfq-iosched: Don't update group weights when on service tree
  fs: assign sb->s_bdi to default_backing_dev_info if the bdi is going away
  block: Require subsystems to explicitly allocate bio_set integrity mempool
  jbd2: finish conversion from WRITE_SYNC_PLUG to WRITE_SYNC and explicit plugging
  jbd: finish conversion from WRITE_SYNC_PLUG to WRITE_SYNC and explicit plugging
  fs: make fsync_buffers_list() plug
  mm: make generic_writepages() use plugging
  blk-cgroup: Add unaccounted time to timeslice_used.
  block: fixup plugging stubs for !CONFIG_BLOCK
  block: remove obsolete comments for blkdev_issue_zeroout.
  blktrace: Use rq->cmd_flags directly in blk_add_trace_rq.
  ...

Fix up conflicts in fs/{aio.c,super.c}
parents 3dab04e6 9d2e157d

Documentation/block/biodoc.txt

+0 −5
Original line number Original line Diff line number Diff line
@@ -963,11 +963,6 @@ elevator_dispatch_fn* fills the dispatch queue with ready requests. 




elevator_add_req_fn*		called to add a new request into the scheduler

elevator_add_req_fn*		called to add a new request into the scheduler





elevator_queue_empty_fn		returns true if the merge queue is empty.

				Drivers shouldn't use this, but rather check

				if elv_next_request is NULL (without losing the

				request if one exists!)



elevator_former_req_fn

elevator_former_req_fn

elevator_latter_req_fn		These return the request before or after the

elevator_latter_req_fn		These return the request before or after the

				one specified in disk sort order. Used by the

				one specified in disk sort order. Used by the

Documentation/cgroups/blkio-controller.txt

+1 −29
Original line number Original line Diff line number Diff line
@@ -140,7 +140,7 @@ Proportional weight policy files 
	- Specifies per cgroup weight. This is default weight of the group

	- Specifies per cgroup weight. This is default weight of the group

	  on all the devices until and unless overridden by per device rule.

	  on all the devices until and unless overridden by per device rule.

	  (See blkio.weight_device).

	  (See blkio.weight_device).

	  Currently allowed range of weights is from 100 to 1000.

	  Currently allowed range of weights is from 10 to 1000.





- blkio.weight_device

- blkio.weight_device

	- One can specify per cgroup per device rules using this interface.

	- One can specify per cgroup per device rules using this interface.
@@ -343,34 +343,6 @@ Common files among various policies 




CFQ sysfs tunable

CFQ sysfs tunable

=================

=================

/sys/block/<disk>/queue/iosched/group_isolation

-----------------------------------------------



If group_isolation=1, it provides stronger isolation between groups at the

expense of throughput. By default group_isolation is 0. In general that

means that if group_isolation=0, expect fairness for sequential workload

only. Set group_isolation=1 to see fairness for random IO workload also.



Generally CFQ will put random seeky workload in sync-noidle category. CFQ

will disable idling on these queues and it does a collective idling on group

of such queues. Generally these are slow moving queues and if there is a

sync-noidle service tree in each group, that group gets exclusive access to

disk for certain period. That means it will bring the throughput down if

group does not have enough IO to drive deeper queue depths and utilize disk

capacity to the fullest in the slice allocated to it. But the flip side is

that even a random reader should get better latencies and overall throughput

if there are lots of sequential readers/sync-idle workload running in the

system.



If group_isolation=0, then CFQ automatically moves all the random seeky queues

in the root group. That means there will be no service differentiation for

that kind of workload. This leads to better throughput as we do collective

idling on root sync-noidle tree.



By default one should run with group_isolation=0. If that is not sufficient

and one wants stronger isolation between groups, then set group_isolation=1

but this will come at cost of reduced throughput.



/sys/block/<disk>/queue/iosched/slice_idle

/sys/block/<disk>/queue/iosched/slice_idle

------------------------------------------

------------------------------------------

On a faster hardware CFQ can be slow, especially with sequential workload.

On a faster hardware CFQ can be slow, especially with sequential workload.

Documentation/iostats.txt

+8 −9
Original line number Original line Diff line number Diff line 
I/O statistics fields

I/O statistics fields

---------------

---------------





Last modified Sep 30, 2003



Since 2.4.20 (and some versions before, with patches), and 2.5.45,

Since 2.4.20 (and some versions before, with patches), and 2.5.45,

more extensive disk statistics have been introduced to help measure disk

more extensive disk statistics have been introduced to help measure disk

activity. Tools such as sar and iostat typically interpret these and do

activity. Tools such as sar and iostat typically interpret these and do
@@ -46,11 +44,12 @@ the above example, the first field of statistics would be 446216. 
By contrast, in 2.6 if you look at /sys/block/hda/stat, you'll

By contrast, in 2.6 if you look at /sys/block/hda/stat, you'll

find just the eleven fields, beginning with 446216.  If you look at

find just the eleven fields, beginning with 446216.  If you look at

/proc/diskstats, the eleven fields will be preceded by the major and

/proc/diskstats, the eleven fields will be preceded by the major and

minor device numbers, and device name.  Each of these formats provide

minor device numbers, and device name.  Each of these formats provides

eleven fields of statistics, each meaning exactly the same things.

eleven fields of statistics, each meaning exactly the same things.

All fields except field 9 are cumulative since boot.  Field 9 should

All fields except field 9 are cumulative since boot.  Field 9 should

go to zero as I/Os complete; all others only increase.  Yes, these are

go to zero as I/Os complete; all others only increase (unless they

32 bit unsigned numbers, and on a very busy or long-lived system they

overflow and wrap).  Yes, these are (32-bit or 64-bit) unsigned long

(native word size) numbers, and on a very busy or long-lived system they

may wrap. Applications should be prepared to deal with that; unless

may wrap. Applications should be prepared to deal with that; unless

your observations are measured in large numbers of minutes or hours,

your observations are measured in large numbers of minutes or hours,

they should not wrap twice before you notice them.

they should not wrap twice before you notice them.
@@ -96,11 +95,11 @@ introduced when changes collide, so (for instance) adding up all the 
read I/Os issued per partition should equal those made to the disks ...

read I/Os issued per partition should equal those made to the disks ...

but due to the lack of locking it may only be very close.

but due to the lack of locking it may only be very close.





In 2.6, there are counters for each cpu, which made the lack of locking

In 2.6, there are counters for each CPU, which make the lack of locking

almost a non-issue.  When the statistics are read, the per-cpu counters

almost a non-issue.  When the statistics are read, the per-CPU counters

are summed (possibly overflowing the unsigned 32-bit variable they are

are summed (possibly overflowing the unsigned long variable they are

summed to) and the result given to the user.  There is no convenient

summed to) and the result given to the user.  There is no convenient

user interface for accessing the per-cpu counters themselves.

user interface for accessing the per-CPU counters themselves.





Disks vs Partitions

Disks vs Partitions

-------------------

-------------------

block/blk-cgroup.c

+15 −1
Original line number Original line Diff line number Diff line
@@ -371,12 +371,14 @@ void blkiocg_update_io_remove_stats(struct blkio_group *blkg, 
}

}

EXPORT_SYMBOL_GPL(blkiocg_update_io_remove_stats);

EXPORT_SYMBOL_GPL(blkiocg_update_io_remove_stats);





void blkiocg_update_timeslice_used(struct blkio_group *blkg, unsigned long time)

void blkiocg_update_timeslice_used(struct blkio_group *blkg, unsigned long time,

				unsigned long unaccounted_time)

{

{

	unsigned long flags;

	unsigned long flags;





	spin_lock_irqsave(&blkg->stats_lock, flags);

	spin_lock_irqsave(&blkg->stats_lock, flags);

	blkg->stats.time += time;

	blkg->stats.time += time;

	blkg->stats.unaccounted_time += unaccounted_time;

	spin_unlock_irqrestore(&blkg->stats_lock, flags);

	spin_unlock_irqrestore(&blkg->stats_lock, flags);

}

}

EXPORT_SYMBOL_GPL(blkiocg_update_timeslice_used);

EXPORT_SYMBOL_GPL(blkiocg_update_timeslice_used);
@@ -604,6 +606,9 @@ static uint64_t blkio_get_stat(struct blkio_group *blkg, 
		return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,

		return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,

					blkg->stats.sectors, cb, dev);

					blkg->stats.sectors, cb, dev);

#ifdef CONFIG_DEBUG_BLK_CGROUP

#ifdef CONFIG_DEBUG_BLK_CGROUP

	if (type == BLKIO_STAT_UNACCOUNTED_TIME)

		return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,

					blkg->stats.unaccounted_time, cb, dev);

	if (type == BLKIO_STAT_AVG_QUEUE_SIZE) {

	if (type == BLKIO_STAT_AVG_QUEUE_SIZE) {

		uint64_t sum = blkg->stats.avg_queue_size_sum;

		uint64_t sum = blkg->stats.avg_queue_size_sum;

		uint64_t samples = blkg->stats.avg_queue_size_samples;

		uint64_t samples = blkg->stats.avg_queue_size_samples;
@@ -1125,6 +1130,9 @@ static int blkiocg_file_read_map(struct cgroup *cgrp, struct cftype *cft, 
			return blkio_read_blkg_stats(blkcg, cft, cb,

			return blkio_read_blkg_stats(blkcg, cft, cb,

						BLKIO_STAT_QUEUED, 1);

						BLKIO_STAT_QUEUED, 1);

#ifdef CONFIG_DEBUG_BLK_CGROUP

#ifdef CONFIG_DEBUG_BLK_CGROUP

		case BLKIO_PROP_unaccounted_time:

			return blkio_read_blkg_stats(blkcg, cft, cb,

						BLKIO_STAT_UNACCOUNTED_TIME, 0);

		case BLKIO_PROP_dequeue:

		case BLKIO_PROP_dequeue:

			return blkio_read_blkg_stats(blkcg, cft, cb,

			return blkio_read_blkg_stats(blkcg, cft, cb,

						BLKIO_STAT_DEQUEUE, 0);

						BLKIO_STAT_DEQUEUE, 0);
@@ -1382,6 +1390,12 @@ struct cftype blkio_files[] = { 
				BLKIO_PROP_dequeue),

				BLKIO_PROP_dequeue),

		.read_map = blkiocg_file_read_map,

		.read_map = blkiocg_file_read_map,

	},

	},

	{

		.name = "unaccounted_time",

		.private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,

				BLKIO_PROP_unaccounted_time),

		.read_map = blkiocg_file_read_map,

	},

#endif

#endif

};

};

block/blk-cgroup.h

+11 −3
Original line number Original line Diff line number Diff line
@@ -49,6 +49,8 @@ enum stat_type { 
	/* All the single valued stats go below this */

	/* All the single valued stats go below this */

	BLKIO_STAT_TIME,

	BLKIO_STAT_TIME,

	BLKIO_STAT_SECTORS,

	BLKIO_STAT_SECTORS,

	/* Time not charged to this cgroup */

	BLKIO_STAT_UNACCOUNTED_TIME,

#ifdef CONFIG_DEBUG_BLK_CGROUP

#ifdef CONFIG_DEBUG_BLK_CGROUP

	BLKIO_STAT_AVG_QUEUE_SIZE,

	BLKIO_STAT_AVG_QUEUE_SIZE,

	BLKIO_STAT_IDLE_TIME,

	BLKIO_STAT_IDLE_TIME,
@@ -81,6 +83,7 @@ enum blkcg_file_name_prop { 
	BLKIO_PROP_io_serviced,

	BLKIO_PROP_io_serviced,

	BLKIO_PROP_time,

	BLKIO_PROP_time,

	BLKIO_PROP_sectors,

	BLKIO_PROP_sectors,

	BLKIO_PROP_unaccounted_time,

	BLKIO_PROP_io_service_time,

	BLKIO_PROP_io_service_time,

	BLKIO_PROP_io_wait_time,

	BLKIO_PROP_io_wait_time,

	BLKIO_PROP_io_merged,

	BLKIO_PROP_io_merged,
@@ -114,6 +117,8 @@ struct blkio_group_stats { 
	/* total disk time and nr sectors dispatched by this group */

	/* total disk time and nr sectors dispatched by this group */

	uint64_t time;

	uint64_t time;

	uint64_t sectors;

	uint64_t sectors;

	/* Time not charged to this cgroup */

	uint64_t unaccounted_time;

	uint64_t stat_arr[BLKIO_STAT_QUEUED + 1][BLKIO_STAT_TOTAL];

	uint64_t stat_arr[BLKIO_STAT_QUEUED + 1][BLKIO_STAT_TOTAL];

#ifdef CONFIG_DEBUG_BLK_CGROUP

#ifdef CONFIG_DEBUG_BLK_CGROUP

	/* Sum of number of IOs queued across all samples */

	/* Sum of number of IOs queued across all samples */
@@ -240,7 +245,7 @@ static inline char *blkg_path(struct blkio_group *blkg) { return NULL; } 




#endif

#endif





#define BLKIO_WEIGHT_MIN	100

#define BLKIO_WEIGHT_MIN	10

#define BLKIO_WEIGHT_MAX	1000

#define BLKIO_WEIGHT_MAX	1000

#define BLKIO_WEIGHT_DEFAULT	500

#define BLKIO_WEIGHT_DEFAULT	500
@@ -293,7 +298,8 @@ extern int blkiocg_del_blkio_group(struct blkio_group *blkg); 
extern struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg,

extern struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg,

						void *key);

						void *key);

void blkiocg_update_timeslice_used(struct blkio_group *blkg,

void blkiocg_update_timeslice_used(struct blkio_group *blkg,

					unsigned long time);

					unsigned long time,

					unsigned long unaccounted_time);

void blkiocg_update_dispatch_stats(struct blkio_group *blkg, uint64_t bytes,

void blkiocg_update_dispatch_stats(struct blkio_group *blkg, uint64_t bytes,

						bool direction, bool sync);

						bool direction, bool sync);

void blkiocg_update_completion_stats(struct blkio_group *blkg,

void blkiocg_update_completion_stats(struct blkio_group *blkg,
@@ -319,7 +325,9 @@ blkiocg_del_blkio_group(struct blkio_group *blkg) { return 0; } 
static inline struct blkio_group *

static inline struct blkio_group *

blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key) { return NULL; }

blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key) { return NULL; }

static inline void blkiocg_update_timeslice_used(struct blkio_group *blkg,

static inline void blkiocg_update_timeslice_used(struct blkio_group *blkg,

						unsigned long time) {}

						unsigned long time,

						unsigned long unaccounted_time)

{}

static inline void blkiocg_update_dispatch_stats(struct blkio_group *blkg,

static inline void blkiocg_update_dispatch_stats(struct blkio_group *blkg,

				uint64_t bytes, bool direction, bool sync) {}

				uint64_t bytes, bool direction, bool sync) {}

static inline void blkiocg_update_completion_stats(struct blkio_group *blkg,

static inline void blkiocg_update_completion_stats(struct blkio_group *blkg,