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Shifted block_recycles so 0 => pure copy-on-write

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This makes a bit more sense with the new block_recycles name.
block_recycles=0 (previously block_recycles=1) requires 1 erase, but it
doesn't really "recycle" the block. With this change, block_recycles=1
"recycles" the block once (2 erases in total) before relocating, which I
think is a bit more intuitive.

Note, this sort of messes with our power-of-2 rounding, as the
block_recycles is technically rounded down to the nearest power-of-2
after adding 1:

- block_recycles=1022 -> 512 erases
- block_recycles=1023 -> 1024 erases
- block_recycles=1024 -> 1024 erases
- block_recycles=1025 -> 1024 erases

But I'm going to keep the block_recycles description more-or-less as is
for now, as I think this extra detail is more confusing than useful,
powers-of-2 stay powers-of-2, and the <=block_recycles contraint is not
violated.
This commit is contained in:
Christopher Haster
2024-05-22 17:53:15 -05:00
parent 4d76551d6b
commit e4fe2b5234
4 changed files with 31 additions and 31 deletions
Download Patch File Download Diff File Expand all files Collapse all files
lfs.c
+5 -7
View File
@@ -15286,9 +15286,6 @@ static int lfs_init(lfs_t *lfs, const struct lfs_config *cfg) {
// // wear-leveling.
// LFS_ASSERT(lfs->cfg->block_cycles != 0);
// block_recycles should not be zero, use -1 to disable
LFS_ASSERT(lfs->cfg->block_recycles != 0);
// inline_size must be <= block_size/4
LFS_ASSERT(lfs->cfg->inline_size <= lfs->cfg->block_size/4);
// shrub_size must be <= block_size/4
@@ -15375,12 +15372,13 @@ static int lfs_init(lfs_t *lfs, const struct lfs_config *cfg) {
// find the number of bits to use for recycle counters
//
// Multiply by 2, since we alternate which metadata block we erase each
// compaction, and limit to 28-bits so we always have some bits to
// determine the most recent revision.
// Add 1, to include the initial erase, multiply by 2, since we
// alternate which metadata block we erase each compaction, and limit
// to 28-bits so we always have some bits to determine the most recent
// revision.
if (lfs->cfg->block_recycles != -1) {
lfs->recycle_bits = lfs_min(
lfs_nlog2(2*lfs->cfg->block_recycles+1)-1,
lfs_nlog2(2*(lfs->cfg->block_recycles+1)+1)-1,
28);
} else {
lfs->recycle_bits = -1;
lfs.h
+4 -2
View File
@@ -209,9 +209,11 @@ struct lfs_config {
// Number of erase cycles before metadata blocks are relocated for
// wear-leveling. Suggested values are in the range 16-1024. Larger values
// relocate less frequently, improving average performance, at the cost
// of worse wear distribution. Note this is rounded down to a power-of-2.
// of worse wear distribution. Note this ends up rounded down to a
// power-of-2.
//
// Set to -1 to disable block-level wear-leveling.
// 0 results in pure copy-on-write, which may be counter-productive. Set
// to -1 to disable block-level wear-leveling.
int32_t block_recycles;
// Size of the read cache in bytes. Larger buffers can improve
tests/test_mtree.toml
+18 -18
View File
@@ -1136,7 +1136,7 @@ code = '''
# this should be set so only one entry can fit in a metadata block
defines.SIZE = 'BLOCK_SIZE / 4'
# make it so blocks relocate every two compacts
defines.BLOCK_RECYCLES = 1
defines.BLOCK_RECYCLES = 0
in = 'lfs.c'
code = '''
lfs_t lfs;
@@ -1221,7 +1221,7 @@ code = '''
# this should be set so only one entry can fit in a metadata block
defines.SIZE = 'BLOCK_SIZE / 4'
# make it so blocks relocate every two compacts
defines.BLOCK_RECYCLES = 1
defines.BLOCK_RECYCLES = 0
in = 'lfs.c'
code = '''
lfs_t lfs;
@@ -1318,7 +1318,7 @@ code = '''
# this should be set so only one entry can fit in a metadata block
defines.SIZE = 'BLOCK_SIZE / 4'
# make it so blocks relocate every two compacts
defines.BLOCK_RECYCLES = 1
defines.BLOCK_RECYCLES = 0
in = 'lfs.c'
code = '''
lfs_t lfs;
@@ -1415,7 +1415,7 @@ code = '''
# this should be set so only one entry can fit in a metadata block
defines.SIZE = 'BLOCK_SIZE / 4'
# make it so blocks relocate every two compacts
defines.BLOCK_RECYCLES = 1
defines.BLOCK_RECYCLES = 0
in = 'lfs.c'
code = '''
lfs_t lfs;
@@ -1469,7 +1469,7 @@ code = '''
# this should be set so only one entry can fit in a metadata block
defines.SIZE = 'BLOCK_SIZE / 4'
# make it so blocks relocate every two compacts
defines.BLOCK_RECYCLES = 1
defines.BLOCK_RECYCLES = 0
# force our block to compact by setting prog_size=block_size, we don't have
# an easy way to force the intermediary mroots to compact otherwise
defines.PROG_SIZE = 'BLOCK_SIZE'
@@ -1540,7 +1540,7 @@ code = '''
# this should be set so only one entry can fit in a metadata block
defines.SIZE = 'BLOCK_SIZE / 4'
# make it so blocks relocate every two compacts
defines.BLOCK_RECYCLES = 1
defines.BLOCK_RECYCLES = 0
in = 'lfs.c'
code = '''
lfs_t lfs;
@@ -1603,7 +1603,7 @@ code = '''
# this should be set so only one entry can fit in a metadata block
defines.SIZE = 'BLOCK_SIZE / 4'
# make it so blocks relocate every two compacts
defines.BLOCK_RECYCLES = 1
defines.BLOCK_RECYCLES = 0
in = 'lfs.c'
code = '''
lfs_t lfs;
@@ -1705,7 +1705,7 @@ code = '''
# this should be set so only one entry can fit in a metadata block
defines.SIZE = 'BLOCK_SIZE / 4'
# make it so blocks relocate every two compacts
defines.BLOCK_RECYCLES = 1
defines.BLOCK_RECYCLES = 0
in = 'lfs.c'
code = '''
lfs_t lfs;
@@ -1824,7 +1824,7 @@ code = '''
# this should be set so only one entry can fit in a metadata block
defines.SIZE = 'BLOCK_SIZE / 4'
# make it so blocks relocate every two compacts
defines.BLOCK_RECYCLES = 1
defines.BLOCK_RECYCLES = 0
in = 'lfs.c'
code = '''
lfs_t lfs;
@@ -1914,7 +1914,7 @@ code = '''
# this should be set so only one entry can fit in a metadata block
defines.SIZE = 'BLOCK_SIZE / 4'
# make it so blocks relocate every two compacts
defines.BLOCK_RECYCLES = 1
defines.BLOCK_RECYCLES = 0
in = 'lfs.c'
code = '''
lfs_t lfs;
@@ -1990,7 +1990,7 @@ code = '''
# this should be set so only one entry can fit in a metadata block
defines.SIZE = 'BLOCK_SIZE / 4'
# make it so blocks relocate every two compacts
defines.BLOCK_RECYCLES = 1
defines.BLOCK_RECYCLES = 0
in = 'lfs.c'
code = '''
lfs_t lfs;
@@ -2076,7 +2076,7 @@ code = '''
[cases.test_mtree_relocate_fuzz]
defines.N = [5, 10, 20, 40]
defines.FORCE_COMPACTION = [false, true]
defines.BLOCK_RECYCLES = [5, 2, 1]
defines.BLOCK_RECYCLES = [5, 1, 0]
defines.SEED = 'range(500)'
in = 'lfs.c'
code = '''
@@ -2555,7 +2555,7 @@ code = '''
[cases.test_mtree_opened_extend]
# make it so blocks relocate every two compacts
defines.BLOCK_RECYCLES = 1
defines.BLOCK_RECYCLES = 0
in = 'lfs.c'
code = '''
lfs_t lfs;
@@ -2613,7 +2613,7 @@ code = '''
# this should be set so only one entry can fit in a metadata block
defines.SIZE = 'BLOCK_SIZE / 4'
# make it so blocks relocate every two compacts
defines.BLOCK_RECYCLES = 1
defines.BLOCK_RECYCLES = 0
in = 'lfs.c'
code = '''
lfs_t lfs;
@@ -2702,7 +2702,7 @@ code = '''
# this should be set so only one entry can fit in a metadata block
defines.SIZE = 'BLOCK_SIZE / 4'
# make it so blocks relocate every two compacts
defines.BLOCK_RECYCLES = 1
defines.BLOCK_RECYCLES = 0
in = 'lfs.c'
code = '''
lfs_t lfs;
@@ -3528,7 +3528,7 @@ code = '''
[cases.test_mtree_traversal_extend]
defines.VALIDATE = [false, true]
# make it so blocks relocate every two compacts
defines.BLOCK_RECYCLES = 1
defines.BLOCK_RECYCLES = 0
in = 'lfs.c'
code = '''
lfs_t lfs;
@@ -4003,7 +4003,7 @@ code = '''
# this should be set so only one entry can fit in a metadata block
defines.SIZE = 'BLOCK_SIZE / 4'
# make it so blocks relocate every two compacts
defines.BLOCK_RECYCLES = 1
defines.BLOCK_RECYCLES = 0
in = 'lfs.c'
code = '''
lfs_t lfs;
@@ -4057,7 +4057,7 @@ code = '''
# this should be set so only one entry can fit in a metadata block
defines.SIZE = 'BLOCK_SIZE / 4'
# make it so blocks relocate every two compacts
defines.BLOCK_RECYCLES = 1
defines.BLOCK_RECYCLES = 0
# force our block to compact by setting prog_size=block_size, we don't have
# any way to indirectly force the intermediary mroots to compact otherwise
defines.PROG_SIZE = 'BLOCK_SIZE'
tests/test_wl.toml
+4 -4
View File
@@ -15,7 +15,7 @@ after = [
# dirs + relocations may create problems for gstate
[cases.test_wl_dir_fuzz]
defines.BLOCK_RECYCLES = [-1, 8, 2, 1]
defines.BLOCK_RECYCLES = [-1, 5, 1, 0]
defines.N = [1, 2, 4, 8, 16, 32, 64, 128, 256, 512]
defines.OPS = 1024
defines.REMOUNT = [false, true]
@@ -163,7 +163,7 @@ code = '''
# files + relocations may create problems for shrubs
[cases.test_wl_file_fuzz]
defines.BLOCK_RECYCLES = [-1, 8, 2, 1]
defines.BLOCK_RECYCLES = [-1, 5, 1, 0]
defines.N = [1, 2, 4, 8, 16, 32, 64]
defines.OPS = 1024
defines.SIZE = [
@@ -374,7 +374,7 @@ code = '''
# open files + relocations may create problems for orphans/zombies
[cases.test_wl_orphanzombie_fuzz]
defines.BLOCK_RECYCLES = [-1, 8, 2, 1]
defines.BLOCK_RECYCLES = [-1, 5, 1, 0]
defines.N = [1, 2, 4, 8, 16, 32, 64]
defines.OPS = 1024
defines.SIZE = [
@@ -713,7 +713,7 @@ code = '''
# open files + dirs + relocations can cause so many problems it's not worth
# listing them
[cases.test_wl_orphanzombiedir_fuzz]
defines.BLOCK_RECYCLES = [-1, 8, 2, 1]
defines.BLOCK_RECYCLES = [-1, 5, 1, 0]
defines.N = [1, 2, 4, 8, 16, 32, 64]
defines.OPS = 1024
defines.SIZE = [