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gc: Made lfsr_fs_gc a bit smarter when flags change

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Now we consider if it's still possible for the current traversal to make
progress. If it can, we continue with the relevant masked flags,
otherwise we restart. This should prevent us from traversing the
filesystem for no reason.

I also reverted the ckedmeta/ckeddata flags, these ended up just adding
code cost. We're not in the stack hot-path anyways...

Code changes:

           code          stack
  before: 36244           2680
  after:  36228 (-0.0%)   2680 (+0.0%)
This commit is contained in:
Christopher Haster
2024-07-17 16:24:48 -05:00
parent c58a48c02e
commit 631bfbc1e8
2 changed files with 48 additions and 42 deletions
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lfs.c
+48 -40
View File
@@ -5924,14 +5924,6 @@ static inline bool lfsr_f_hasorphans(uint32_t flags) {
return flags & LFS_F_ORPHANS;
}
static inline bool lfsr_f_hasckedmeta(uint32_t flags) {
return flags & LFS_F_CKEDMETA;
}
static inline bool lfsr_f_hasckeddata(uint32_t flags) {
return flags & LFS_F_CKEDDATA;
}
// on-demand flags
// needed in lfsr_fs_isinconsistent
@@ -13040,14 +13032,6 @@ int lfsr_fs_gc(lfs_t *lfs, lfs_soff_t steps, uint32_t flags) {
LFS_ASSERT(!lfsr_t_ismtreeonly(flags) || !lfsr_t_islookahead(flags));
LFS_ASSERT(!lfsr_t_ismtreeonly(flags) || !lfsr_t_isckdata(flags));
// do we really need a full traversal?
if (!(lfsr_t_islookahead(flags)
|| lfsr_t_iscompact(flags)
|| lfsr_t_isckmeta(flags)
|| lfsr_t_isckdata(flags))) {
flags |= LFS_T_MTREEONLY;
}
// fix pending grms if requested
if (lfsr_t_ismkconsistent(flags)
&& lfsr_grm_count(lfs) > 0) {
@@ -13069,42 +13053,54 @@ int lfsr_fs_gc(lfs_t *lfs, lfs_soff_t steps, uint32_t flags) {
}
}
// every time we call lfsr_fs_gc with ckmeta/ckdata, assume we want
// a new traversal
lfs->flags &= ~(LFS_F_CKEDMETA | LFS_F_CKEDDATA);
// do we have any pending work?
while ((lfs_off_t)steps > 0
&& ((lfsr_t_ismkconsistent(flags)
&& lfsr_f_hasorphans(lfs->flags))
|| (lfsr_t_islookahead(flags)
&& lfsr_fs_canlookahead(lfs))
|| (lfsr_t_iscompact(flags)
&& lfsr_i_isuncompacted(lfs->flags))
|| (lfsr_t_isckmeta(flags)
&& !lfsr_f_hasckedmeta(lfs->flags))
|| (lfsr_t_isckdata(flags)
&& !lfsr_f_hasckeddata(lfs->flags)))) {
uint32_t pending = flags & (
((lfsr_f_hasorphans(lfs->flags)) ? LFS_GC_MKCONSISTENT : 0)
| ((lfsr_fs_canlookahead(lfs)) ? LFS_GC_LOOKAHEAD : 0)
| ((lfsr_i_isuncompacted(lfs->flags)) ? LFS_GC_COMPACT : 0)
| LFS_GC_CKMETA
| LFS_GC_CKDATA);
while (pending && (lfs_off_t)steps > 0) {
// checkpoint the allocator to maximize any lookahead scans
lfs_alloc_ckpoint(lfs);
// start a new traversal?
if (!lfsr_omdir_isopen(lfs, &lfs->gc.o.o)) {
lfs->gc = LFSR_TRAVERSAL(flags);
lfs->gc = LFSR_TRAVERSAL(pending);
lfsr_omdir_open(lfs, &lfs->gc.o.o);
// existing traversal?
} else {
// note that we mask flags (except mtreeonly)! if you change flags
// mid-traversal, the result is equivalent to the worst-case set
// of flags
// mask flags, we can't trust existing traversals to make
// progress if flags change
lfs->gc.o.o.flags &= ~(
LFS_GC_MKCONSISTENT
| LFS_GC_LOOKAHEAD
| LFS_GC_COMPACT
| LFS_GC_CKMETA
| LFS_GC_CKDATA
) | flags;
) | pending;
// will this traversal still make progress? no? start over
if (!(lfs->gc.o.o.flags & (
LFS_GC_MKCONSISTENT
| LFS_GC_LOOKAHEAD
| LFS_GC_COMPACT
| LFS_GC_CKMETA
| LFS_GC_CKDATA))) {
lfsr_omdir_close(lfs, &lfs->gc.o.o);
continue;
}
}
// do we really need a full traversal?
if (!(lfs->gc.o.o.flags & (
LFS_GC_LOOKAHEAD
| LFS_GC_COMPACT
| LFS_GC_CKMETA
| LFS_GC_CKDATA))) {
lfs->gc.o.o.flags |= LFS_T_MTREEONLY;
}
// progress gc
@@ -13114,13 +13110,25 @@ int lfsr_fs_gc(lfs_t *lfs, lfs_soff_t steps, uint32_t flags) {
return err;
}
// end of traversal?
if (err == LFS_ERR_NOENT) {
lfsr_omdir_close(lfs, &lfs->gc.o.o);
// consider our filesystem checked if we complete at least
// one traversal
lfs->flags |= ((lfsr_t_isckmeta(flags)) ? LFS_F_CKEDMETA : 0)
| ((lfsr_t_isckdata(flags)) ? LFS_F_CKEDDATA : 0);
// clear any pending flags we make progress on
pending &= ~(
((!lfsr_f_hasorphans(lfs->flags))
? LFS_GC_MKCONSISTENT
: 0)
| ((!lfsr_fs_canlookahead(lfs))
? LFS_GC_LOOKAHEAD
: 0)
| ((!lfsr_i_isuncompacted(lfs->flags))
? LFS_GC_COMPACT
: 0)
// consider our filesystem checked if we complete at
// least one traversal
| LFS_GC_CKMETA
| LFS_GC_CKDATA);
}
// decrement steps
lfs.h
-2
View File
@@ -140,8 +140,6 @@ enum lfs_fsinfo_flags {
// internally used flags
LFS_F_ORPHANS = 0x8000, // Filesystem may have untracked orphans
LFS_F_CKEDMETA = 0x2000, // Filesystem metadata checked during gc
LFS_F_CKEDDATA = 0x4000, // Filesystem data checked during gc
};
// File types