Github/littlefs
1
Fork 0
Code Actions Activity

trv: Split lfs3_trv_t -> lfs3_trv_t, lfs3_mgc_t, and lfs3_mtrv_t

Browse Source 
A big downside of LFS3_T_REBUILDGBMAP is the addition of an lfs3_btree_t
struct to _every_ traversal object.

Unfortunately, I don't see a way around this. We need to track the new
gbmap snapshot _somewhere_, and other options (such as a global gbmap.b_
snapshot) just move the RAM around without actually saving anything.

To at least mitigate this internally, this splits lfs3_trv_t into
distinct lfs3_trv_t, lfs3_mgc_t, and lfs3_mtrv_t structs that capture
only the relevant state for internal traversal layers:

- lfs3_mtree_traverse <- lfs3_mtrv_t
- lfs3_mtree_gc       <- lfs3_mgc_t (contains lfs3_mtrv_t)
- lfs3_trv_read       <- lfs3_trv_t (contains lfs3_mgc_t)

This minimizes the impact of the gbmap rebuild snapshots, and saves a
big chunk of RAM. As a plus it also saves RAM in the default build by
limiting the 2-block block queue to the high-level lfs3_trv_read API:

                 code          stack          ctx
  before:       37176           2360          684
  after:        37176 (+0.0%)   2352 (-0.3%)  684 (+0.0%)

                 code          stack          ctx
  gbmap before: 40060           2432          848
  gbmap after:  40024 (-0.1%)   2368 (-2.6%)  848 (+0.0%)

The main downside? Our field names are continuing in their
ridiculousness:

  lfs3.gc.gc.t.b.h.flags // where else would the global gc flags be?
This commit is contained in:
Christopher Haster
2025-10-16 00:10:21 -05:00
parent 06bc4dff04
commit fb90bf976c
6 changed files with 299 additions and 285 deletions
Download Patch File Download Diff File Expand all files Collapse all files
tests/test_ck.toml
+4 -4
View File
@@ -1025,7 +1025,7 @@ code = '''
}
if (tinfo.btype == LFS3_BTYPE_BTREE
&& lfs3_t_tstate(trv.b.h.flags) != LFS3_TSTATE_GBMAP) {
&& lfs3_t_tstate(trv.gc.t.b.h.flags) != LFS3_TSTATE_GBMAP) {
if (k == i) {
// clobber this block
printf("clobbering 0x%x\n", tinfo.block);
@@ -1125,7 +1125,7 @@ code = '''
if ((tinfo.btype == LFS3_BTYPE_BTREE
|| tinfo.btype == LFS3_BTYPE_DATA)
&& lfs3_t_tstate(trv.b.h.flags) != LFS3_TSTATE_GBMAP) {
&& lfs3_t_tstate(trv.gc.t.b.h.flags) != LFS3_TSTATE_GBMAP) {
if (k == i) {
// clobber this block
printf("clobbering 0x%x\n", tinfo.block);
@@ -1231,7 +1231,7 @@ code = '''
}
if (tinfo.btype == LFS3_BTYPE_BTREE
&& lfs3_t_tstate(trv.b.h.flags) != LFS3_TSTATE_GBMAP) {
&& lfs3_t_tstate(trv.gc.t.b.h.flags) != LFS3_TSTATE_GBMAP) {
// found an interesting block?
if (k == i) {
badblock = tinfo.block;
@@ -1382,7 +1382,7 @@ code = '''
if ((tinfo.btype == LFS3_BTYPE_BTREE
|| tinfo.btype == LFS3_BTYPE_DATA)
&& lfs3_t_tstate(trv.b.h.flags) != LFS3_TSTATE_GBMAP) {
&& lfs3_t_tstate(trv.gc.t.b.h.flags) != LFS3_TSTATE_GBMAP) {
// found an interesting block?
if (k == i) {
badblock = tinfo.block;