[PATCH 12/15] libnvdimm: enable iostat

Dan Williams
2015-06-17T23:58:40Z

This is disabled by default as the overhead is prohibitive, but if the
user takes the action to turn it on we'll oblige.

Reviewed-by: Vishal Verma <vishal.l.verma@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
drivers/nvdimm/Kconfig | 14 ++++++++++++++
drivers/nvdimm/blk.c | 7 ++++++-
drivers/nvdimm/btt.c | 7 ++++++-
drivers/nvdimm/core.c | 31 +++++++++++++++++++++++++++++++
drivers/nvdimm/nd.h | 13 +++++++++++++
drivers/nvdimm/pmem.c | 5 +++++
6 files changed, 75 insertions(+), 2 deletions(-)

diff --git a/drivers/nvdimm/Kconfig b/drivers/nvdimm/Kconfig
index 912cb36b8435..9d72085a67c9 100644
--- a/drivers/nvdimm/Kconfig
+++ b/drivers/nvdimm/Kconfig
@@ -73,4 +73,18 @@ config ND_MAX_REGIONS

Leave the default of 64 if you are unsure.

+config ND_IOSTAT
+ bool "Enable iostat by default"
+ default n
+ ---help---
+ Persistent memory i/o has very low latency to the point
+ where the overhead to measure statistics can dramatically
+ impact the relative performance of the driver. Say y here
+ to trade off performance for statistics gathering that is
+ enabled by default. These statistics can always be
+ enabled/disabled at run time via the 'iostat' attribute of
+ the block device's queue in sysfs.
+
+ If unsure, say N
+
endif
diff --git a/drivers/nvdimm/blk.c b/drivers/nvdimm/blk.c
index 9d609ef95266..8a65e5a500d8 100644
--- a/drivers/nvdimm/blk.c
+++ b/drivers/nvdimm/blk.c
@@ -168,8 +168,10 @@ static void nd_blk_make_request(struct request_queue *q, struct bio *bio)
struct bio_integrity_payload *bip;
struct nd_blk_device *blk_dev;
struct bvec_iter iter;
+ unsigned long start;
struct bio_vec bvec;
int err = 0, rw;
+ bool do_acct;

if (unlikely(bio_end_sector(bio) > get_capacity(disk))) {
err = -EIO;
@@ -191,6 +193,7 @@ static void nd_blk_make_request(struct request_queue *q, struct bio *bio)
blk_dev = disk->private_data;

rw = bio_data_dir(bio);
+ do_acct = nd_iostat_start(bio, &start);
bio_for_each_segment(bvec, bio, iter) {
unsigned int len = bvec.bv_len;

@@ -202,9 +205,11 @@ static void nd_blk_make_request(struct request_queue *q, struct bio *bio)
"io error in %s sector %lld, len %d,\n",
(rw == READ) ? "READ" : "WRITE",
(unsigned long long) iter.bi_sector, len);
- goto out;
+ break;
}
}
+ if (do_acct)
+ nd_iostat_end(bio, start);

out:
bio_endio(bio, err);
diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
index 83b798dd2e68..67484633c322 100644
--- a/drivers/nvdimm/btt.c
+++ b/drivers/nvdimm/btt.c
@@ -1178,8 +1178,10 @@ static void btt_make_request(struct request_queue *q, struct bio *bio)
struct block_device *bdev = bio->bi_bdev;
struct btt *btt = q->queuedata;
struct bvec_iter iter;
+ unsigned long start;
struct bio_vec bvec;
int err = 0, rw;
+ bool do_acct;

if (bio_end_sector(bio) > get_capacity(bdev->bd_disk)) {
err = -EIO;
@@ -1199,6 +1201,7 @@ static void btt_make_request(struct request_queue *q, struct bio *bio)
goto out;
}

+ do_acct = nd_iostat_start(bio, &start);
bio_for_each_segment(bvec, bio, iter) {
unsigned int len = bvec.bv_len;

@@ -1215,9 +1218,11 @@ static void btt_make_request(struct request_queue *q, struct bio *bio)
"io error in %s sector %lld, len %d,\n",
(rw == READ) ? "READ" : "WRITE",
(unsigned long long) iter.bi_sector, len);
- goto out;
+ break;
}
}
+ if (do_acct)
+ nd_iostat_end(bio, start);

out:
bio_endio(bio, err);
diff --git a/drivers/nvdimm/core.c b/drivers/nvdimm/core.c
index d27b13357873..99cf95af5f24 100644
--- a/drivers/nvdimm/core.c
+++ b/drivers/nvdimm/core.c
@@ -218,9 +218,40 @@ void nd_blk_queue_init(struct request_queue *q)
{
blk_queue_max_hw_sectors(q, UINT_MAX);
blk_queue_bounce_limit(q, BLK_BOUNCE_ANY);
+ if (IS_ENABLED(CONFIG_ND_IOSTAT))
+ queue_flag_set_unlocked(QUEUE_FLAG_IO_STAT, q);
}
EXPORT_SYMBOL(nd_blk_queue_init);

+void __nd_iostat_start(struct bio *bio, unsigned long *start)
+{
+ struct gendisk *disk = bio->bi_bdev->bd_disk;
+ const int rw = bio_data_dir(bio);
+ int cpu = part_stat_lock();
+
+ *start = jiffies;
+ part_round_stats(cpu, &disk->part0);
+ part_stat_inc(cpu, &disk->part0, ios[rw]);
+ part_stat_add(cpu, &disk->part0, sectors[rw], bio_sectors(bio));
+ part_inc_in_flight(&disk->part0, rw);
+ part_stat_unlock();
+}
+EXPORT_SYMBOL(__nd_iostat_start);
+
+void nd_iostat_end(struct bio *bio, unsigned long start)
+{
+ struct gendisk *disk = bio->bi_bdev->bd_disk;
+ unsigned long duration = jiffies - start;
+ const int rw = bio_data_dir(bio);
+ int cpu = part_stat_lock();
+
+ part_stat_add(cpu, &disk->part0, ticks[rw], duration);
+ part_round_stats(cpu, &disk->part0);
+ part_dec_in_flight(&disk->part0, rw);
+ part_stat_unlock();
+}
+EXPORT_SYMBOL(nd_iostat_end);
+
static ssize_t commands_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
diff --git a/drivers/nvdimm/nd.h b/drivers/nvdimm/nd.h
index 2f20d5dca028..3c4c8b6c64ec 100644
--- a/drivers/nvdimm/nd.h
+++ b/drivers/nvdimm/nd.h
@@ -13,6 +13,7 @@
#ifndef __ND_H__
#define __ND_H__
#include <linux/libnvdimm.h>
+#include <linux/blkdev.h>
#include <linux/device.h>
#include <linux/genhd.h>
#include <linux/mutex.h>
@@ -172,5 +173,17 @@ struct resource *nvdimm_allocate_dpa(struct nvdimm_drvdata *ndd,
resource_size_t n);
int nd_blk_region_init(struct nd_region *nd_region);
void nd_blk_queue_init(struct request_queue *q);
+void __nd_iostat_start(struct bio *bio, unsigned long *start);
+static inline bool nd_iostat_start(struct bio *bio, unsigned long *start)
+{
+ struct gendisk *disk = bio->bi_bdev->bd_disk;
+
+ if (!blk_queue_io_stat(disk->queue))
+ return false;
+
+ __nd_iostat_start(bio, start);
+ return true;
+}
+void nd_iostat_end(struct bio *bio, unsigned long start);
resource_size_t nd_namespace_blk_validate(struct nd_namespace_blk *nsblk);
#endif /* __ND_H__ */
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 0337b00f5409..3fd854a78f09 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -59,6 +59,8 @@ static void pmem_do_bvec(struct pmem_device *pmem, struct page *page,
static void pmem_make_request(struct request_queue *q, struct bio *bio)
{
int err = 0;
+ bool do_acct;
+ unsigned long start;
struct bio_vec bvec;
struct bvec_iter iter;
struct block_device *bdev = bio->bi_bdev;
@@ -69,9 +71,12 @@ static void pmem_make_request(struct request_queue *q, struct bio *bio)
goto out;
}

+ do_acct = nd_iostat_start(bio, &start);
bio_for_each_segment(bvec, bio, iter)
pmem_do_bvec(pmem, bvec.bv_page, bvec.bv_len, bvec.bv_offset,
bio_data_dir(bio), iter.bi_sector);
+ if (do_acct)
+ nd_iostat_end(bio, start);

out:
bio_endio(bio, err);