dm thin: sort the per thin deferred bios using an rb_tree
A thin-pool will allocate blocks using FIFO order for all thin devices
which share the thin-pool. Because of this simplistic allocation the
thin-pool's space can become fragmented quite easily; especially when
multiple threads are requesting blocks in parallel.
Sort each thin device's deferred_bio_list based on logical sector to
help reduce fragmentation of the thin-pool's ondisk layout.
The following tables illustrate the realized gains/potential offered by
sorting each thin device's deferred_bio_list. An "io size"-sized random
read of the device would result in "seeks/io" fragments being read, with
an average "distance/seek" between each fragment.
Data was written to a single thin device using multiple threads via
iozone (8 threads, 64K for both the block_size and io_size).
unsorted:
io size seeks/io distance/seek
--------------------------------------
4k 0.000 0b
16k 0.013 11m
64k 0.065 11m
256k 0.274 10m
1m 1.109 10m
4m 4.411 10m
16m 17.097 11m
64m 60.055 13m
256m 148.798 25m
1g 809.929 21m
sorted:
io size seeks/io distance/seek
--------------------------------------
4k 0.000 0b
16k 0.000 1g
64k 0.001 1g
256k 0.003 1g
1m 0.011 1g
4m 0.045 1g
16m 0.181 1g
64m 0.747 1011m
256m 3.299 1g
1g 14.373 1g
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Joe Thornber <ejt@redhat.com>
This commit is contained in:
Mike Snitzer
parent
c140e1c4e2
commit
67324ea188
|
|
@ -16,6 +16,7 @@
|
|||
#include <linux/init.h>
|
||||
#include <linux/module.h>
|
||||
#include <linux/slab.h>
|
||||
#include <linux/rbtree.h>
|
||||
|
||||
#define DM_MSG_PREFIX "thin"
|
||||
|
||||
|
|
@ -230,6 +231,7 @@ struct thin_c {
|
|||
spinlock_t lock;
|
||||
struct bio_list deferred_bio_list;
|
||||
struct bio_list retry_on_resume_list;
|
||||
struct rb_root sort_bio_list; /* sorted list of deferred bios */
|
||||
};
|
||||
|
||||
/*----------------------------------------------------------------*/
|
||||
|
|
@ -371,6 +373,7 @@ struct dm_thin_endio_hook {
|
|||
struct dm_deferred_entry *shared_read_entry;
|
||||
struct dm_deferred_entry *all_io_entry;
|
||||
struct dm_thin_new_mapping *overwrite_mapping;
|
||||
struct rb_node rb_node;
|
||||
};
|
||||
|
||||
static void requeue_bio_list(struct thin_c *tc, struct bio_list *master)
|
||||
|
|
@ -1367,12 +1370,77 @@ static int need_commit_due_to_time(struct pool *pool)
|
|||
jiffies > pool->last_commit_jiffies + COMMIT_PERIOD;
|
||||
}
|
||||
|
||||
#define thin_pbd(node) rb_entry((node), struct dm_thin_endio_hook, rb_node)
|
||||
#define thin_bio(pbd) dm_bio_from_per_bio_data((pbd), sizeof(struct dm_thin_endio_hook))
|
||||
|
||||
static void __thin_bio_rb_add(struct thin_c *tc, struct bio *bio)
|
||||
{
|
||||
struct rb_node **rbp, *parent;
|
||||
struct dm_thin_endio_hook *pbd;
|
||||
sector_t bi_sector = bio->bi_iter.bi_sector;
|
||||
|
||||
rbp = &tc->sort_bio_list.rb_node;
|
||||
parent = NULL;
|
||||
while (*rbp) {
|
||||
parent = *rbp;
|
||||
pbd = thin_pbd(parent);
|
||||
|
||||
if (bi_sector < thin_bio(pbd)->bi_iter.bi_sector)
|
||||
rbp = &(*rbp)->rb_left;
|
||||
else
|
||||
rbp = &(*rbp)->rb_right;
|
||||
}
|
||||
|
||||
pbd = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
|
||||
rb_link_node(&pbd->rb_node, parent, rbp);
|
||||
rb_insert_color(&pbd->rb_node, &tc->sort_bio_list);
|
||||
}
|
||||
|
||||
static void __extract_sorted_bios(struct thin_c *tc)
|
||||
{
|
||||
struct rb_node *node;
|
||||
struct dm_thin_endio_hook *pbd;
|
||||
struct bio *bio;
|
||||
|
||||
for (node = rb_first(&tc->sort_bio_list); node; node = rb_next(node)) {
|
||||
pbd = thin_pbd(node);
|
||||
bio = thin_bio(pbd);
|
||||
|
||||
bio_list_add(&tc->deferred_bio_list, bio);
|
||||
rb_erase(&pbd->rb_node, &tc->sort_bio_list);
|
||||
}
|
||||
|
||||
WARN_ON(!RB_EMPTY_ROOT(&tc->sort_bio_list));
|
||||
}
|
||||
|
||||
static void __sort_thin_deferred_bios(struct thin_c *tc)
|
||||
{
|
||||
struct bio *bio;
|
||||
struct bio_list bios;
|
||||
|
||||
bio_list_init(&bios);
|
||||
bio_list_merge(&bios, &tc->deferred_bio_list);
|
||||
bio_list_init(&tc->deferred_bio_list);
|
||||
|
||||
/* Sort deferred_bio_list using rb-tree */
|
||||
while ((bio = bio_list_pop(&bios)))
|
||||
__thin_bio_rb_add(tc, bio);
|
||||
|
||||
/*
|
||||
* Transfer the sorted bios in sort_bio_list back to
|
||||
* deferred_bio_list to allow lockless submission of
|
||||
* all bios.
|
||||
*/
|
||||
__extract_sorted_bios(tc);
|
||||
}
|
||||
|
||||
static void process_thin_deferred_bios(struct thin_c *tc)
|
||||
{
|
||||
struct pool *pool = tc->pool;
|
||||
unsigned long flags;
|
||||
struct bio *bio;
|
||||
struct bio_list bios;
|
||||
struct blk_plug plug;
|
||||
|
||||
if (tc->requeue_mode) {
|
||||
requeue_bio_list(tc, &tc->deferred_bio_list);
|
||||
|
|
@ -1382,10 +1450,20 @@ static void process_thin_deferred_bios(struct thin_c *tc)
|
|||
bio_list_init(&bios);
|
||||
|
||||
spin_lock_irqsave(&tc->lock, flags);
|
||||
|
||||
if (bio_list_empty(&tc->deferred_bio_list)) {
|
||||
spin_unlock_irqrestore(&tc->lock, flags);
|
||||
return;
|
||||
}
|
||||
|
||||
__sort_thin_deferred_bios(tc);
|
||||
|
||||
bio_list_merge(&bios, &tc->deferred_bio_list);
|
||||
bio_list_init(&tc->deferred_bio_list);
|
||||
|
||||
spin_unlock_irqrestore(&tc->lock, flags);
|
||||
|
||||
blk_start_plug(&plug);
|
||||
while ((bio = bio_list_pop(&bios))) {
|
||||
/*
|
||||
* If we've got no free new_mapping structs, and processing
|
||||
|
|
@ -1405,6 +1483,7 @@ static void process_thin_deferred_bios(struct thin_c *tc)
|
|||
else
|
||||
pool->process_bio(tc, bio);
|
||||
}
|
||||
blk_finish_plug(&plug);
|
||||
}
|
||||
|
||||
static void process_deferred_bios(struct pool *pool)
|
||||
|
|
@ -2964,7 +3043,7 @@ static struct target_type pool_target = {
|
|||
.name = "thin-pool",
|
||||
.features = DM_TARGET_SINGLETON | DM_TARGET_ALWAYS_WRITEABLE |
|
||||
DM_TARGET_IMMUTABLE,
|
||||
.version = {1, 11, 0},
|
||||
.version = {1, 12, 0},
|
||||
.module = THIS_MODULE,
|
||||
.ctr = pool_ctr,
|
||||
.dtr = pool_dtr,
|
||||
|
|
@ -3040,6 +3119,7 @@ static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv)
|
|||
spin_lock_init(&tc->lock);
|
||||
bio_list_init(&tc->deferred_bio_list);
|
||||
bio_list_init(&tc->retry_on_resume_list);
|
||||
tc->sort_bio_list = RB_ROOT;
|
||||
|
||||
if (argc == 3) {
|
||||
r = dm_get_device(ti, argv[2], FMODE_READ, &origin_dev);
|
||||
|
|
@ -3287,7 +3367,7 @@ static int thin_iterate_devices(struct dm_target *ti,
|
|||
|
||||
static struct target_type thin_target = {
|
||||
.name = "thin",
|
||||
.version = {1, 11, 0},
|
||||
.version = {1, 12, 0},
|
||||
.module = THIS_MODULE,
|
||||
.ctr = thin_ctr,
|
||||
.dtr = thin_dtr,
|
||||
|
|
|
|||
Loading…
Reference in New Issue