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block: Seperate read and write statistics of in_flight requests v2

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Commit a9327cac44 added seperate read
and write statistics of in_flight requests. And exported the number
of read and write requests in progress seperately through sysfs.

But  Corrado Zoccolo <czoccolo@gmail.com> reported getting strange
output from "iostat -kx 2". Global values for service time and
utilization were garbage. For interval values, utilization was always
100%, and service time is higher than normal.

So this was reverted by commit 0f78ab9899

The problem was in part_round_stats_single(), I missed the following:
        if (now == part->stamp)
                return;

-       if (part->in_flight) {
+       if (part_in_flight(part)) {
                __part_stat_add(cpu, part, time_in_queue,
                                part_in_flight(part) * (now - part->stamp));
                __part_stat_add(cpu, part, io_ticks, (now - part->stamp));

With this chunk included, the reported regression gets fixed.

Signed-off-by: Nikanth Karthikesan <knikanth@suse.de>

--
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Nikanth Karthikesan 2009-10-06 20:16:55 +02:00 committed by Jens Axboe
parent 23e018a1b0
commit 316d315bff
6 changed files with 43 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
block/blk-core.c
View File

@ -70,7 +70,7 @@ static void drive_stat_acct(struct request *rq, int new_io)
part_stat_inc(cpu, part, merges[rw]);
else {
part_round_stats(cpu, part);
part_inc_in_flight(part);
part_inc_in_flight(part, rw);
}
part_stat_unlock();
@ -1030,9 +1030,9 @@ static void part_round_stats_single(int cpu, struct hd_struct *part,
if (now == part->stamp)
return;
if (part->in_flight) {
if (part_in_flight(part)) {
__part_stat_add(cpu, part, time_in_queue,
part->in_flight * (now - part->stamp));
part_in_flight(part) * (now - part->stamp));
__part_stat_add(cpu, part, io_ticks, (now - part->stamp));
}
part->stamp = now;
@ -1739,7 +1739,7 @@ static void blk_account_io_done(struct request *req)
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_dec_in_flight(part, rw);
part_stat_unlock();
}

2
block/blk-merge.c
View File

@ -351,7 +351,7 @@ static void blk_account_io_merge(struct request *req)
part = disk_map_sector_rcu(req->rq_disk, blk_rq_pos(req));
part_round_stats(cpu, part);
part_dec_in_flight(part);
part_dec_in_flight(part, rq_data_dir(req));
part_stat_unlock();
}

4
block/genhd.c
View File

@ -869,6 +869,7 @@ static DEVICE_ATTR(size, S_IRUGO, part_size_show, NULL);
static DEVICE_ATTR(alignment_offset, S_IRUGO, disk_alignment_offset_show, NULL);
static DEVICE_ATTR(capability, S_IRUGO, disk_capability_show, NULL);
static DEVICE_ATTR(stat, S_IRUGO, part_stat_show, NULL);
static DEVICE_ATTR(inflight, S_IRUGO, part_inflight_show, NULL);
#ifdef CONFIG_FAIL_MAKE_REQUEST
static struct device_attribute dev_attr_fail =
__ATTR(make-it-fail, S_IRUGO|S_IWUSR, part_fail_show, part_fail_store);
@ -888,6 +889,7 @@ static struct attribute *disk_attrs[] = {
&dev_attr_alignment_offset.attr,
&dev_attr_capability.attr,
&dev_attr_stat.attr,
&dev_attr_inflight.attr,
#ifdef CONFIG_FAIL_MAKE_REQUEST
&dev_attr_fail.attr,
#endif
@ -1053,7 +1055,7 @@ static int diskstats_show(struct seq_file *seqf, void *v)
part_stat_read(hd, merges[1]),
(unsigned long long)part_stat_read(hd, sectors[1]),
jiffies_to_msecs(part_stat_read(hd, ticks[1])),
hd->in_flight,
part_in_flight(hd),
jiffies_to_msecs(part_stat_read(hd, io_ticks)),
jiffies_to_msecs(part_stat_read(hd, time_in_queue))
);

16
drivers/md/dm.c
View File

@ -130,7 +130,7 @@ struct mapped_device {
/*
* A list of ios that arrived while we were suspended.
*/
atomic_t pending;
atomic_t pending[2];
wait_queue_head_t wait;
struct work_struct work;
struct bio_list deferred;
@ -453,13 +453,14 @@ static void start_io_acct(struct dm_io *io)
{
struct mapped_device *md = io->md;
int cpu;
int rw = bio_data_dir(io->bio);
io->start_time = jiffies;
cpu = part_stat_lock();
part_round_stats(cpu, &dm_disk(md)->part0);
part_stat_unlock();
dm_disk(md)->part0.in_flight = atomic_inc_return(&md->pending);
dm_disk(md)->part0.in_flight[rw] = atomic_inc_return(&md->pending[rw]);
}
static void end_io_acct(struct dm_io *io)
@ -479,8 +480,9 @@ static void end_io_acct(struct dm_io *io)
* After this is decremented the bio must not be touched if it is
* a barrier.
*/
dm_disk(md)->part0.in_flight = pending =
atomic_dec_return(&md->pending);
dm_disk(md)->part0.in_flight[rw] = pending =
atomic_dec_return(&md->pending[rw]);
pending += atomic_read(&md->pending[rw^0x1]);
/* nudge anyone waiting on suspend queue */
if (!pending)
@ -1785,7 +1787,8 @@ static struct mapped_device *alloc_dev(int minor)
if (!md->disk)
goto bad_disk;
atomic_set(&md->pending, 0);
atomic_set(&md->pending[0], 0);
atomic_set(&md->pending[1], 0);
init_waitqueue_head(&md->wait);
INIT_WORK(&md->work, dm_wq_work);
init_waitqueue_head(&md->eventq);
@ -2088,7 +2091,8 @@ static int dm_wait_for_completion(struct mapped_device *md, int interruptible)
break;
}
spin_unlock_irqrestore(q->queue_lock, flags);
} else if (!atomic_read(&md->pending))
} else if (!atomic_read(&md->pending[0]) &&
!atomic_read(&md->pending[1]))
break;
if (interruptible == TASK_INTERRUPTIBLE &&

12
fs/partitions/check.c
View File

@ -248,11 +248,19 @@ ssize_t part_stat_show(struct device *dev,
part_stat_read(p, merges[WRITE]),
(unsigned long long)part_stat_read(p, sectors[WRITE]),
jiffies_to_msecs(part_stat_read(p, ticks[WRITE])),
p->in_flight,
part_in_flight(p),
jiffies_to_msecs(part_stat_read(p, io_ticks)),
jiffies_to_msecs(part_stat_read(p, time_in_queue)));
}
ssize_t part_inflight_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct hd_struct *p = dev_to_part(dev);
return sprintf(buf, "%8u %8u\n", p->in_flight[0], p->in_flight[1]);
}
#ifdef CONFIG_FAIL_MAKE_REQUEST
ssize_t part_fail_show(struct device *dev,
struct device_attribute *attr, char *buf)
@ -281,6 +289,7 @@ static DEVICE_ATTR(start, S_IRUGO, part_start_show, NULL);
static DEVICE_ATTR(size, S_IRUGO, part_size_show, NULL);
static DEVICE_ATTR(alignment_offset, S_IRUGO, part_alignment_offset_show, NULL);
static DEVICE_ATTR(stat, S_IRUGO, part_stat_show, NULL);
static DEVICE_ATTR(inflight, S_IRUGO, part_inflight_show, NULL);
#ifdef CONFIG_FAIL_MAKE_REQUEST
static struct device_attribute dev_attr_fail =
__ATTR(make-it-fail, S_IRUGO|S_IWUSR, part_fail_show, part_fail_store);
@ -292,6 +301,7 @@ static struct attribute *part_attrs[] = {
&dev_attr_size.attr,
&dev_attr_alignment_offset.attr,
&dev_attr_stat.attr,
&dev_attr_inflight.attr,
#ifdef CONFIG_FAIL_MAKE_REQUEST
&dev_attr_fail.attr,
#endif

21
include/linux/genhd.h
View File

@ -98,7 +98,7 @@ struct hd_struct {
int make_it_fail;
#endif
unsigned long stamp;
int in_flight;
int in_flight[2];
#ifdef CONFIG_SMP
struct disk_stats *dkstats;
#else
@ -322,18 +322,23 @@ static inline void free_part_stats(struct hd_struct *part)
#define part_stat_sub(cpu, gendiskp, field, subnd) \
part_stat_add(cpu, gendiskp, field, -subnd)
static inline void part_inc_in_flight(struct hd_struct *part)
static inline void part_inc_in_flight(struct hd_struct *part, int rw)
{
part->in_flight++;
part->in_flight[rw]++;
if (part->partno)
part_to_disk(part)->part0.in_flight++;
part_to_disk(part)->part0.in_flight[rw]++;
}
static inline void part_dec_in_flight(struct hd_struct *part)
static inline void part_dec_in_flight(struct hd_struct *part, int rw)
{
part->in_flight--;
part->in_flight[rw]--;
if (part->partno)
part_to_disk(part)->part0.in_flight--;
part_to_disk(part)->part0.in_flight[rw]--;
}
static inline int part_in_flight(struct hd_struct *part)
{
return part->in_flight[0] + part->in_flight[1];
}
/* block/blk-core.c */
@ -546,6 +551,8 @@ extern ssize_t part_size_show(struct device *dev,
struct device_attribute *attr, char *buf);
extern ssize_t part_stat_show(struct device *dev,
struct device_attribute *attr, char *buf);
extern ssize_t part_inflight_show(struct device *dev,
struct device_attribute *attr, char *buf);
#ifdef CONFIG_FAIL_MAKE_REQUEST
extern ssize_t part_fail_show(struct device *dev,
struct device_attribute *attr, char *buf);