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dm: add 'use_blk_mq' module param and expose in per-device ro sysfs attr

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Request-based DM's blk-mq support defaults to off; but a user can easily
change the default using the dm_mod.use_blk_mq module/boot option.

Also, you can check what mode a given request-based DM device is using
with: cat /sys/block/dm-X/dm/use_blk_mq

This change enabled further cleanup and reduced work (e.g. the
md->io_pool and md->rq_pool isn't created if using blk-mq).

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Mike Snitzer 2015-03-11 15:01:09 -04:00
parent 022333427a
commit 17e149b8f7
6 changed files with 76 additions and 16 deletions
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8
Documentation/ABI/testing/sysfs-block-dm
View File

@ -37,3 +37,11 @@ Description: Allow control over how long a request that is a
accounting. This attribute is not applicable to
bio-based DM devices so it will only ever report 0 for
them.
What: /sys/block/dm-<num>/dm/use_blk_mq
Date: March 2015
KernelVersion: 4.1
Contact: dm-devel@redhat.com
Description: Request-based Device-mapper blk-mq I/O path mode.
Contains the value 1 if the device is using blk-mq.
Otherwise it contains 0. Read-only attribute.

11
drivers/md/Kconfig
View File

@ -196,6 +196,17 @@ config BLK_DEV_DM
If unsure, say N.
config DM_MQ_DEFAULT
bool "request-based DM: use blk-mq I/O path by default"
depends on BLK_DEV_DM
---help---
This option enables the blk-mq based I/O path for request-based
DM devices by default. With the option the dm_mod.use_blk_mq
module/boot option defaults to Y, without it to N, but it can
still be overriden either way.
If unsure say N.
config DM_DEBUG
bool "Device mapper debugging support"
depends on BLK_DEV_DM

9
drivers/md/dm-sysfs.c
View File

@ -89,15 +89,24 @@ static ssize_t dm_attr_suspended_show(struct mapped_device *md, char *buf)
return strlen(buf);
}
static ssize_t dm_attr_use_blk_mq_show(struct mapped_device *md, char *buf)
{
sprintf(buf, "%d\n", dm_use_blk_mq(md));
return strlen(buf);
}
static DM_ATTR_RO(name);
static DM_ATTR_RO(uuid);
static DM_ATTR_RO(suspended);
static DM_ATTR_RO(use_blk_mq);
static DM_ATTR_RW(rq_based_seq_io_merge_deadline);
static struct attribute *dm_attrs[] = {
&dm_attr_name.attr,
&dm_attr_uuid.attr,
&dm_attr_suspended.attr,
&dm_attr_use_blk_mq.attr,
&dm_attr_rq_based_seq_io_merge_deadline.attr,
NULL,
};

6
drivers/md/dm-table.c
View File

@ -940,7 +940,7 @@ bool dm_table_mq_request_based(struct dm_table *t)
return dm_table_get_type(t) == DM_TYPE_MQ_REQUEST_BASED;
}
static int dm_table_alloc_md_mempools(struct dm_table *t)
static int dm_table_alloc_md_mempools(struct dm_table *t, struct mapped_device *md)
{
unsigned type = dm_table_get_type(t);
unsigned per_bio_data_size = 0;
@ -958,7 +958,7 @@ static int dm_table_alloc_md_mempools(struct dm_table *t)
per_bio_data_size = max(per_bio_data_size, tgt->per_bio_data_size);
}
t->mempools = dm_alloc_md_mempools(type, t->integrity_supported, per_bio_data_size);
t->mempools = dm_alloc_md_mempools(md, type, t->integrity_supported, per_bio_data_size);
if (!t->mempools)
return -ENOMEM;
@ -1128,7 +1128,7 @@ int dm_table_complete(struct dm_table *t)
return r;
}
r = dm_table_alloc_md_mempools(t);
r = dm_table_alloc_md_mempools(t, t->md);
if (r)
DMERR("unable to allocate mempools");

53
drivers/md/dm.c
View File

@ -228,8 +228,20 @@ struct mapped_device {
/* for blk-mq request-based DM support */
struct blk_mq_tag_set tag_set;
bool use_blk_mq;
};
#ifdef CONFIG_DM_MQ_DEFAULT
static bool use_blk_mq = true;
#else
static bool use_blk_mq = false;
#endif
bool dm_use_blk_mq(struct mapped_device *md)
{
return md->use_blk_mq;
}
/*
* For mempools pre-allocation at the table loading time.
*/
@ -2034,7 +2046,7 @@ ssize_t dm_attr_rq_based_seq_io_merge_deadline_store(struct mapped_device *md,
{
unsigned deadline;
if (!dm_request_based(md))
if (!dm_request_based(md) || md->use_blk_mq)
return count;
if (kstrtouint(buf, 10, &deadline))
@ -2222,6 +2234,7 @@ static void dm_init_md_queue(struct mapped_device *md)
static void dm_init_old_md_queue(struct mapped_device *md)
{
md->use_blk_mq = false;
dm_init_md_queue(md);
/*
@ -2263,6 +2276,7 @@ static struct mapped_device *alloc_dev(int minor)
if (r < 0)
goto bad_io_barrier;
md->use_blk_mq = use_blk_mq;
md->type = DM_TYPE_NONE;
mutex_init(&md->suspend_lock);
mutex_init(&md->type_lock);
@ -2349,7 +2363,6 @@ static void unlock_fs(struct mapped_device *md);
static void free_dev(struct mapped_device *md)
{
int minor = MINOR(disk_devt(md->disk));
bool using_blk_mq = !!md->queue->mq_ops;
unlock_fs(md);
destroy_workqueue(md->wq);
@ -2375,7 +2388,7 @@ static void free_dev(struct mapped_device *md)
del_gendisk(md->disk);
put_disk(md->disk);
blk_cleanup_queue(md->queue);
if (using_blk_mq)
if (md->use_blk_mq)
blk_mq_free_tag_set(&md->tag_set);
bdput(md->bdev);
free_minor(minor);
@ -2388,7 +2401,7 @@ static void __bind_mempools(struct mapped_device *md, struct dm_table *t)
{
struct dm_md_mempools *p = dm_table_get_md_mempools(t);
if (md->io_pool && md->bs) {
if (md->bs) {
/* The md already has necessary mempools. */
if (dm_table_get_type(t) == DM_TYPE_BIO_BASED) {
/*
@ -2798,13 +2811,21 @@ out_tag_set:
return err;
}
static unsigned filter_md_type(unsigned type, struct mapped_device *md)
{
if (type == DM_TYPE_BIO_BASED)
return type;
return !md->use_blk_mq ? DM_TYPE_REQUEST_BASED : DM_TYPE_MQ_REQUEST_BASED;
}
/*
* Setup the DM device's queue based on md's type
*/
int dm_setup_md_queue(struct mapped_device *md)
{
int r;
unsigned md_type = dm_get_md_type(md);
unsigned md_type = filter_md_type(dm_get_md_type(md), md);
switch (md_type) {
case DM_TYPE_REQUEST_BASED:
@ -3509,16 +3530,19 @@ int dm_noflush_suspending(struct dm_target *ti)
}
EXPORT_SYMBOL_GPL(dm_noflush_suspending);
struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity, unsigned per_bio_data_size)
struct dm_md_mempools *dm_alloc_md_mempools(struct mapped_device *md, unsigned type,
unsigned integrity, unsigned per_bio_data_size)
{
struct dm_md_mempools *pools = kzalloc(sizeof(*pools), GFP_KERNEL);
struct kmem_cache *cachep;
struct kmem_cache *cachep = NULL;
unsigned int pool_size = 0;
unsigned int front_pad;
if (!pools)
return NULL;
type = filter_md_type(type, md);
switch (type) {
case DM_TYPE_BIO_BASED:
cachep = _io_cache;
@ -3526,13 +3550,13 @@ struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity, u
front_pad = roundup(per_bio_data_size, __alignof__(struct dm_target_io)) + offsetof(struct dm_target_io, clone);
break;
case DM_TYPE_REQUEST_BASED:
cachep = _rq_tio_cache;
pool_size = dm_get_reserved_rq_based_ios();
pools->rq_pool = mempool_create_slab_pool(pool_size, _rq_cache);
if (!pools->rq_pool)
goto out;
/* fall through to setup remaining rq-based pools */
case DM_TYPE_MQ_REQUEST_BASED:
cachep = _rq_tio_cache;
if (!pool_size)
pool_size = dm_get_reserved_rq_based_ios();
front_pad = offsetof(struct dm_rq_clone_bio_info, clone);
@ -3540,12 +3564,14 @@ struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity, u
WARN_ON(per_bio_data_size != 0);
break;
default:
goto out;
BUG();
}
pools->io_pool = mempool_create_slab_pool(pool_size, cachep);
if (!pools->io_pool)
goto out;
if (cachep) {
pools->io_pool = mempool_create_slab_pool(pool_size, cachep);
if (!pools->io_pool)
goto out;
}
pools->bs = bioset_create_nobvec(pool_size, front_pad);
if (!pools->bs)
@ -3602,6 +3628,9 @@ MODULE_PARM_DESC(reserved_bio_based_ios, "Reserved IOs in bio-based mempools");
module_param(reserved_rq_based_ios, uint, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(reserved_rq_based_ios, "Reserved IOs in request-based mempools");
module_param(use_blk_mq, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(use_blk_mq, "Use block multiqueue for request-based DM devices");
MODULE_DESCRIPTION(DM_NAME " driver");
MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
MODULE_LICENSE("GPL");

5
drivers/md/dm.h
View File

@ -211,6 +211,8 @@ int dm_kobject_uevent(struct mapped_device *md, enum kobject_action action,
void dm_internal_suspend(struct mapped_device *md);
void dm_internal_resume(struct mapped_device *md);
bool dm_use_blk_mq(struct mapped_device *md);
int dm_io_init(void);
void dm_io_exit(void);
@ -220,7 +222,8 @@ void dm_kcopyd_exit(void);
/*
* Mempool operations
*/
struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity, unsigned per_bio_data_size);
struct dm_md_mempools *dm_alloc_md_mempools(struct mapped_device *md, unsigned type,
unsigned integrity, unsigned per_bio_data_size);
void dm_free_md_mempools(struct dm_md_mempools *pools);
/*