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Btrfs: add mount -o ssd_spread to spread allocations out

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Some SSDs perform best when reusing block numbers often, while
others perform much better when clustering strictly allocates
big chunks of unused space.

The default mount -o ssd will find rough groupings of blocks
where there are a bunch of free blocks that might have some
allocated blocks mixed in.

mount -o ssd_spread will make sure there are no allocated blocks
mixed in.  It should perform better on lower end SSDs.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason 2009-06-09 20:28:34 -04:00
parent c604480171
commit 451d7585a8
5 changed files with 22 additions and 6 deletions
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1
fs/btrfs/ctree.h
View File

@ -1100,6 +1100,7 @@ struct btrfs_root {
#define BTRFS_MOUNT_COMPRESS (1 << 5)
#define BTRFS_MOUNT_NOTREELOG (1 << 6)
#define BTRFS_MOUNT_FLUSHONCOMMIT (1 << 7)
#define BTRFS_MOUNT_SSD_SPREAD (1 << 8)
#define btrfs_clear_opt(o, opt) ((o) &= ~BTRFS_MOUNT_##opt)
#define btrfs_set_opt(o, opt) ((o) |= BTRFS_MOUNT_##opt)

2
fs/btrfs/extent-tree.c
View File

@ -3607,7 +3607,7 @@ static noinline int find_free_extent(struct btrfs_trans_handle *trans,
last_ptr_loop = 0;
/* allocate a cluster in this block group */
ret = btrfs_find_space_cluster(trans,
ret = btrfs_find_space_cluster(trans, root,
block_group, last_ptr,
offset, num_bytes,
empty_cluster + empty_size);

5
fs/btrfs/free-space-cache.c
View File

@ -579,6 +579,7 @@ u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
* it returns -enospc
*/
int btrfs_find_space_cluster(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_block_group_cache *block_group,
struct btrfs_free_cluster *cluster,
u64 offset, u64 bytes, u64 empty_size)
@ -595,7 +596,9 @@ int btrfs_find_space_cluster(struct btrfs_trans_handle *trans,
int ret;
/* for metadata, allow allocates with more holes */
if (block_group->flags & BTRFS_BLOCK_GROUP_METADATA) {
if (btrfs_test_opt(root, SSD_SPREAD)) {
min_bytes = bytes + empty_size;
} else if (block_group->flags & BTRFS_BLOCK_GROUP_METADATA) {
/*
* we want to do larger allocations when we are
* flushing out the delayed refs, it helps prevent

1
fs/btrfs/free-space-cache.h
View File

@ -31,6 +31,7 @@ void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
u64 bytes);
u64 btrfs_block_group_free_space(struct btrfs_block_group_cache *block_group);
int btrfs_find_space_cluster(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_block_group_cache *block_group,
struct btrfs_free_cluster *cluster,
u64 offset, u64 bytes, u64 empty_size);

19
fs/btrfs/super.c
View File

@ -66,8 +66,8 @@ static void btrfs_put_super(struct super_block *sb)
enum {
Opt_degraded, Opt_subvol, Opt_device, Opt_nodatasum, Opt_nodatacow,
Opt_max_extent, Opt_max_inline, Opt_alloc_start, Opt_nobarrier,
Opt_ssd, Opt_nossd, Opt_thread_pool, Opt_noacl, Opt_compress,
Opt_notreelog, Opt_ratio, Opt_flushoncommit, Opt_err,
Opt_ssd, Opt_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl,
Opt_compress, Opt_notreelog, Opt_ratio, Opt_flushoncommit, Opt_err,
};
static match_table_t tokens = {
@ -83,6 +83,7 @@ static match_table_t tokens = {
{Opt_thread_pool, "thread_pool=%d"},
{Opt_compress, "compress"},
{Opt_ssd, "ssd"},
{Opt_ssd_spread, "ssd_spread"},
{Opt_nossd, "nossd"},
{Opt_noacl, "noacl"},
{Opt_notreelog, "notreelog"},
@ -174,9 +175,17 @@ int btrfs_parse_options(struct btrfs_root *root, char *options)
printk(KERN_INFO "btrfs: use ssd allocation scheme\n");
btrfs_set_opt(info->mount_opt, SSD);
break;
case Opt_ssd_spread:
printk(KERN_INFO "btrfs: use spread ssd "
"allocation scheme\n");
btrfs_set_opt(info->mount_opt, SSD);
btrfs_set_opt(info->mount_opt, SSD_SPREAD);
break;
case Opt_nossd:
printk(KERN_INFO "btrfs: not using ssd allocation scheme\n");
printk(KERN_INFO "btrfs: not using ssd allocation "
"scheme\n");
btrfs_clear_opt(info->mount_opt, SSD);
btrfs_clear_opt(info->mount_opt, SSD_SPREAD);
break;
case Opt_nobarrier:
printk(KERN_INFO "btrfs: turning off barriers\n");
@ -429,7 +438,9 @@ static int btrfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
if (btrfs_test_opt(root, COMPRESS))
seq_puts(seq, ",compress");
if (btrfs_test_opt(root, SSD))
if (btrfs_test_opt(root, SSD_SPREAD))
seq_puts(seq, ",ssd_spread");
else if (btrfs_test_opt(root, SSD))
seq_puts(seq, ",ssd");
if (btrfs_test_opt(root, NOTREELOG))
seq_puts(seq, ",notreelog");