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block: add sysfs file for controlling io stats accounting

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This allows us to turn off disk stat accounting completely, for the cases
where the 0.5-1% reduction in system time is important.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Jens Axboe 2009-01-23 10:54:44 +01:00
parent 7598909e3e
commit bc58ba9468
3 changed files with 88 additions and 36 deletions
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90
block/blk-core.c
View File

@ -64,11 +64,12 @@ static struct workqueue_struct *kblockd_workqueue;
static void drive_stat_acct(struct request *rq, int new_io)
{
struct gendisk *disk = rq->rq_disk;
struct hd_struct *part;
int rw = rq_data_dir(rq);
int cpu;
if (!blk_fs_request(rq) || !rq->rq_disk)
if (!blk_fs_request(rq) || !disk || !blk_queue_io_stat(disk->queue))
return;
cpu = part_stat_lock();
@ -599,8 +600,7 @@ blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
q->request_fn = rfn;
q->prep_rq_fn = NULL;
q->unplug_fn = generic_unplug_device;
q->queue_flags = (1 << QUEUE_FLAG_CLUSTER |
1 << QUEUE_FLAG_STACKABLE);
q->queue_flags = QUEUE_FLAG_DEFAULT;
q->queue_lock = lock;
blk_queue_segment_boundary(q, BLK_SEG_BOUNDARY_MASK);
@ -1663,6 +1663,55 @@ void blkdev_dequeue_request(struct request *req)
}
EXPORT_SYMBOL(blkdev_dequeue_request);
static void blk_account_io_completion(struct request *req, unsigned int bytes)
{
struct gendisk *disk = req->rq_disk;
if (!disk || !blk_queue_io_stat(disk->queue))
return;
if (blk_fs_request(req)) {
const int rw = rq_data_dir(req);
struct hd_struct *part;
int cpu;
cpu = part_stat_lock();
part = disk_map_sector_rcu(req->rq_disk, req->sector);
part_stat_add(cpu, part, sectors[rw], bytes >> 9);
part_stat_unlock();
}
}
static void blk_account_io_done(struct request *req)
{
struct gendisk *disk = req->rq_disk;
if (!disk || !blk_queue_io_stat(disk->queue))
return;
/*
* Account IO completion. bar_rq isn't accounted as a normal
* IO on queueing nor completion. Accounting the containing
* request is enough.
*/
if (blk_fs_request(req) && req != &req->q->bar_rq) {
unsigned long duration = jiffies - req->start_time;
const int rw = rq_data_dir(req);
struct hd_struct *part;
int cpu;
cpu = part_stat_lock();
part = disk_map_sector_rcu(disk, req->sector);
part_stat_inc(cpu, part, ios[rw]);
part_stat_add(cpu, part, ticks[rw], duration);
part_round_stats(cpu, part);
part_dec_in_flight(part);
part_stat_unlock();
}
}
/**
* __end_that_request_first - end I/O on a request
* @req: the request being processed
@ -1698,16 +1747,7 @@ static int __end_that_request_first(struct request *req, int error,
(unsigned long long)req->sector);
}
if (blk_fs_request(req) && req->rq_disk) {
const int rw = rq_data_dir(req);
struct hd_struct *part;
int cpu;
cpu = part_stat_lock();
part = disk_map_sector_rcu(req->rq_disk, req->sector);
part_stat_add(cpu, part, sectors[rw], nr_bytes >> 9);
part_stat_unlock();
}
blk_account_io_completion(req, nr_bytes);
total_bytes = bio_nbytes = 0;
while ((bio = req->bio) != NULL) {
@ -1787,8 +1827,6 @@ static int __end_that_request_first(struct request *req, int error,
*/
static void end_that_request_last(struct request *req, int error)
{
struct gendisk *disk = req->rq_disk;
if (blk_rq_tagged(req))
blk_queue_end_tag(req->q, req);
@ -1800,27 +1838,7 @@ static void end_that_request_last(struct request *req, int error)
blk_delete_timer(req);
/*
* Account IO completion. bar_rq isn't accounted as a normal
* IO on queueing nor completion. Accounting the containing
* request is enough.
*/
if (disk && blk_fs_request(req) && req != &req->q->bar_rq) {
unsigned long duration = jiffies - req->start_time;
const int rw = rq_data_dir(req);
struct hd_struct *part;
int cpu;
cpu = part_stat_lock();
part = disk_map_sector_rcu(disk, req->sector);
part_stat_inc(cpu, part, ios[rw]);
part_stat_add(cpu, part, ticks[rw], duration);
part_round_stats(cpu, part);
part_dec_in_flight(part);
part_stat_unlock();
}
blk_account_io_done(req);
if (req->end_io)
req->end_io(req, error);

28
block/blk-sysfs.c
View File

@ -197,6 +197,27 @@ queue_rq_affinity_store(struct request_queue *q, const char *page, size_t count)
return ret;
}
static ssize_t queue_iostats_show(struct request_queue *q, char *page)
{
return queue_var_show(blk_queue_io_stat(q), page);
}
static ssize_t queue_iostats_store(struct request_queue *q, const char *page,
size_t count)
{
unsigned long stats;
ssize_t ret = queue_var_store(&stats, page, count);
spin_lock_irq(q->queue_lock);
if (stats)
queue_flag_set(QUEUE_FLAG_IO_STAT, q);
else
queue_flag_clear(QUEUE_FLAG_IO_STAT, q);
spin_unlock_irq(q->queue_lock);
return ret;
}
static struct queue_sysfs_entry queue_requests_entry = {
.attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
.show = queue_requests_show,
@ -249,6 +270,12 @@ static struct queue_sysfs_entry queue_rq_affinity_entry = {
.store = queue_rq_affinity_store,
};
static struct queue_sysfs_entry queue_iostats_entry = {
.attr = {.name = "iostats", .mode = S_IRUGO | S_IWUSR },
.show = queue_iostats_show,
.store = queue_iostats_store,
};
static struct attribute *default_attrs[] = {
&queue_requests_entry.attr,
&queue_ra_entry.attr,
@ -259,6 +286,7 @@ static struct attribute *default_attrs[] = {
&queue_nonrot_entry.attr,
&queue_nomerges_entry.attr,
&queue_rq_affinity_entry.attr,
&queue_iostats_entry.attr,
NULL,
};

6
include/linux/blkdev.h
View File

@ -451,6 +451,11 @@ struct request_queue
#define QUEUE_FLAG_STACKABLE 13 /* supports request stacking */
#define QUEUE_FLAG_NONROT 14 /* non-rotational device (SSD) */
#define QUEUE_FLAG_VIRT QUEUE_FLAG_NONROT /* paravirt device */
#define QUEUE_FLAG_IO_STAT 15 /* do IO stats */
#define QUEUE_FLAG_DEFAULT ((1 << QUEUE_FLAG_IO_STAT) | \
(1 << QUEUE_FLAG_CLUSTER) | \
1 << QUEUE_FLAG_STACKABLE)
static inline int queue_is_locked(struct request_queue *q)
{
@ -567,6 +572,7 @@ enum {
#define blk_queue_stopped(q) test_bit(QUEUE_FLAG_STOPPED, &(q)->queue_flags)
#define blk_queue_nomerges(q) test_bit(QUEUE_FLAG_NOMERGES, &(q)->queue_flags)
#define blk_queue_nonrot(q) test_bit(QUEUE_FLAG_NONROT, &(q)->queue_flags)
#define blk_queue_io_stat(q) test_bit(QUEUE_FLAG_IO_STAT, &(q)->queue_flags)
#define blk_queue_flushing(q) ((q)->ordseq)
#define blk_queue_stackable(q) \
test_bit(QUEUE_FLAG_STACKABLE, &(q)->queue_flags)