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trv: Adopted LFS3_t_STALE for marking block queue as stale

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This solves the previous gc-needs-block-queue-so-we-can-clobber-block-
queue issue by adding an additional LFS3_t_STALE flag to indicate when
any block queues would be invalid.

So instead of clearing block queues in lfs3_alloc_ckpoint, we just set
LFS3_t_STALE, and any lfs3_trv_ts can clear their block queues in
lfs3_trv_read. This allows lfs3_mgc_ts to be allocated without a block
queue when doing any LFS3_M_*/LFS3_F_*/LFS3_GC_* work.

LFS3_t_STALE is set at the same time as LFS3_t_CKPOINT and LFS3_t_DIRTY,
but we need a separate bit so lfs3_trv_read can clear the flag after
flushing without losing ckpoint/dirty information.

---

Unfortunately, none of the stack-allocated lfs3_mgc_ts are on the stack
hot-path, so we don't immediate savings. But note the 2-words saved in
ctx when compiling in LFS3_GC mode:

                 code          stack          ctx
  before:       35940           2280          660
  after:        35944 (+0.0%)   2280 (+0.0%)  660 (+0.0%)

                 code          stack          ctx
  gbmap before: 38916           2296          772
  gbmap after:  38916 (+0.0%)   2296 (+0.0%)  772 (+0.0%)

                 code          stack          ctx
  gc before:    36012           2280          776
  gc after:     36016 (+0.0%)   2280 (+0.0%)  768 (-1.0%)
This commit is contained in:
Christopher Haster
2025-11-08 01:40:01 -06:00
parent d1d69c0a52
commit 14c369af93
4 changed files with 69 additions and 75 deletions
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tests/test_gc.toml
+18 -18
View File
@@ -57,7 +57,7 @@ code = '''
struct lfs3_fsinfo fsinfo;
lfs3_fs_stat(&lfs3, &fsinfo) => 0;
assert(fsinfo.flags & LFS3_I_RELOOKAHEAD);
assert(lfs3.handles != &lfs3.gc.gc.t.h);
assert(lfs3.handles != &lfs3.gc.t.h);
// run GC until we make progress
for (lfs3_block_t i = 0;; i++) {
@@ -127,11 +127,11 @@ code = '''
struct lfs3_fsinfo fsinfo;
lfs3_fs_stat(&lfs3, &fsinfo) => 0;
assert(fsinfo.flags & LFS3_I_RELOOKAHEAD);
assert(lfs3.handles != &lfs3.gc.gc.t.h);
assert(lfs3.handles != &lfs3.gc.t.h);
// run GC one step
lfs3_fs_gc(&lfs3) => 0;
assert(lfs3.handles == &lfs3.gc.gc.t.h);
assert(lfs3.handles == &lfs3.gc.t.h);
// mutate the filesystem
lfs3_file_open(&lfs3, &file, "spider",
@@ -143,7 +143,7 @@ code = '''
lfs3_file_close(&lfs3, &file) => 0;
// run GC until our traversal is done
while (lfs3.handles == &lfs3.gc.gc.t.h) {
while (lfs3.handles == &lfs3.gc.t.h) {
lfs3_fs_gc(&lfs3) => 0;
}
@@ -318,7 +318,7 @@ code = '''
struct lfs3_fsinfo fsinfo;
lfs3_fs_stat(&lfs3, &fsinfo) => 0;
assert(fsinfo.flags & LFS3_I_REGBMAP);
assert(lfs3.handles != &lfs3.gc.gc.t.h);
assert(lfs3.handles != &lfs3.gc.t.h);
// run GC until we make progress
for (lfs3_block_t i = 0;; i++) {
@@ -391,11 +391,11 @@ code = '''
struct lfs3_fsinfo fsinfo;
lfs3_fs_stat(&lfs3, &fsinfo) => 0;
assert(fsinfo.flags & LFS3_I_REGBMAP);
assert(lfs3.handles != &lfs3.gc.gc.t.h);
assert(lfs3.handles != &lfs3.gc.t.h);
// run GC one step
lfs3_fs_gc(&lfs3) => 0;
assert(lfs3.handles == &lfs3.gc.gc.t.h);
assert(lfs3.handles == &lfs3.gc.t.h);
// mutate the filesystem
lfs3_file_open(&lfs3, &file, "spider",
@@ -407,7 +407,7 @@ code = '''
lfs3_file_close(&lfs3, &file) => 0;
// run GC until our traversal is done
while (lfs3.handles == &lfs3.gc.gc.t.h) {
while (lfs3.handles == &lfs3.gc.t.h) {
lfs3_fs_gc(&lfs3) => 0;
}
@@ -592,7 +592,7 @@ code = '''
struct lfs3_fsinfo fsinfo;
lfs3_fs_stat(&lfs3, &fsinfo) => 0;
assert(fsinfo.flags & LFS3_I_COMPACTMETA);
assert(lfs3.handles != &lfs3.gc.gc.t.h);
assert(lfs3.handles != &lfs3.gc.t.h);
// run GC until we make progress
for (lfs3_block_t i = 0;; i++) {
@@ -684,19 +684,19 @@ code = '''
struct lfs3_fsinfo fsinfo;
lfs3_fs_stat(&lfs3, &fsinfo) => 0;
assert(fsinfo.flags & LFS3_I_COMPACTMETA);
assert(lfs3.handles != &lfs3.gc.gc.t.h);
assert(lfs3.handles != &lfs3.gc.t.h);
// run GC one traversal + one step
while (true) {
lfs3_fs_gc(&lfs3) => 0;
// internal traversal done?
if (lfs3.handles != &lfs3.gc.gc.t.h) {
if (lfs3.handles != &lfs3.gc.t.h) {
break;
}
}
lfs3_fs_gc(&lfs3) => 0;
assert(lfs3.handles == &lfs3.gc.gc.t.h);
assert(lfs3.handles == &lfs3.gc.t.h);
// mutate the filesystem
lfs3_file_rewind(&lfs3, &file) => 0;
@@ -707,7 +707,7 @@ code = '''
lfs3_file_sync(&lfs3, &file) => 0;
// run GC until our traversal is done (twice for compactmeta)
while (lfs3.handles == &lfs3.gc.gc.t.h) {
while (lfs3.handles == &lfs3.gc.t.h) {
lfs3_fs_gc(&lfs3) => 0;
}
@@ -811,7 +811,7 @@ code = '''
struct lfs3_fsinfo fsinfo;
lfs3_fs_stat(&lfs3, &fsinfo) => 0;
assert(fsinfo.flags & LFS3_I_MKCONSISTENT);
assert(lfs3.handles != &lfs3.gc.gc.t.h);
assert(lfs3.handles != &lfs3.gc.t.h);
// run GC until we make progress
for (lfs3_block_t i = 0;; i++) {
@@ -917,7 +917,7 @@ code = '''
lfs3_fs_stat(&lfs3, &fsinfo) => 0;
assert(fsinfo.flags & LFS3_I_MKCONSISTENT);
#ifdef LFS3_GC
assert(lfs3.handles != &lfs3.gc.gc.t.h);
assert(lfs3.handles != &lfs3.gc.t.h);
#endif
// call lfs3_fs_mkconsistent
@@ -1021,9 +1021,9 @@ code = '''
}
// run GC one step
assert(lfs3.handles != &lfs3.gc.gc.t.h);
assert(lfs3.handles != &lfs3.gc.t.h);
lfs3_fs_gc(&lfs3) => 0;
assert(lfs3.handles == &lfs3.gc.gc.t.h);
assert(lfs3.handles == &lfs3.gc.t.h);
// create the rest of the orphans after GC has started
for (lfs3_size_t i = 0; i < ORPHANS; i++) {
@@ -1045,7 +1045,7 @@ code = '''
assert(fsinfo.flags & LFS3_I_MKCONSISTENT);
// run GC until our traversal is done
while (lfs3.handles == &lfs3.gc.gc.t.h) {
while (lfs3.handles == &lfs3.gc.t.h) {
lfs3_fs_gc(&lfs3) => 0;
}