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It turns out the btree key cache shrinker wasn't actually reclaiming
anything, prior to the previous patch. This adds instrumentation so that
if we have further issues we can see what's going on.
Specifically, sysfs internal/btree_key_cache is greatly expanded with
new counters, and the SRCU sequence numbers of the first 10 entries on
each pending freelist, and we also add trigger_btree_key_cache_shrink
for testing without having to prune all the system caches.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Freeing key cache items is a multi stage process; we need to wait for an
SRCU grace period to elapse, and we handle this ourselves - partially to
avoid callback overhead, but primarily so that when allocating we can
first allocate from the freed items waiting for an SRCU grace period.
Previously, the shrinker was counting the items on the 'waiting for SRCU
grace period' lists as items being scanned, but this meant that too many
items waiting for an SRCU grace period could prevent it from doing any
work at all.
After this, we're seeing that items skipped due to the accessed bit are
the main cause of the shrinker not making any progress, and we actually
want the key cache shrinker to run quite aggressively because reclaimed
items will still generally be found (more compactly) in the btree node
cache - so we also tweak the shrinker to not count those against
nr_to_scan.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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this stores the SRCU sequence number, which we use to check if an SRCU
barrier has elapsed; this is a partial fix for the key cache shrinker
not actually freeing.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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The btree write buffer flush fastpath that avoids the main transaction
commit path had the unfortunate side effect of not doing btree node
merging.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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There's been a bug in the btree write buffer where it wasn't triggering
btree node merges - and leaving behind a bunch of nearly empty btree
nodes.
Then during journal replay, when updates to the backpointers btree
aren't using the btree write buffer (because we require synchronization
with journal replay), we end up doing those merges all at once.
Then if it's the interior update path running them, we deadlock because
those run with the highest watermark.
There's no real need for the interior update path to be doing btree node
merges; other code paths can handle that at lower watermarks.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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This fixes a deadlock where the interior update path during journal
replay ends up doing a ton of merges on the backpointers btree, and
deadlocking.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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With the new assertions, we shouldn't be holding locks when
trans->locked is false, thus, we shouldn't use relock when we just want
to check if we can relock.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Add a field for tracking whether a transaction object holds btree locks,
and assertions to verify state.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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We're about to add new asserts for btree_trans locking consistency, and
part of that requires that aren't using the btree_trans while it's
unlocked.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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In the key cache fill path, we use path_upgrade() on a path that isn't
uptodate yet but should be locked.
This change makes bch2_btree_path_upgrade() slightly looser so we can
use it in key cache upgrade, instead of the __ version.
Also, make the related assert - that path->uptodate implies nodes_locked
- slightly clearer.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Commit ec9cc18fc2e6 ("bcachefs: Add checks for invalid snapshot IDs")
intends to check the sanity of a snapshot and panic when
BCACHEFS_DEBUG is set, but that conditional has a typo.
Fix the typo to refer to the actual existing Kconfig symbol.
This was found with ./scripts/checkkconfigsymbols.py.
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@redhat.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Since commit 43a7206b0963 ("driver core: class: make class_register() take
a const *"), the driver core allows for struct class to be in read-only
memory, so move the bch_chardev_class structure to be declared at build
time placing it into read-only memory, instead of having to be dynamically
allocated at boot time. Also, correctly clean up after failing paths in
bch2_chardev_init().
Cc: Hongbo Li <lihongbo22@huawei.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ricardo B. Marliere <ricardo@marliere.net>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Some renaming for better consistency
bch2_member_exists -> bch2_member_alive
bch2_dev_exists -> bch2_member_exists
bch2_dev_exsits2 -> bch2_dev_exists
bch_dev_locked -> bch2_dev_locked
bch_dev_bkey_exists -> bch2_dev_bkey_exists
new helper - bch2_dev_safe
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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cut out a branch from doing it the obvious way
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Factor out slowpath into a separate helper
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Add a new helper that calls dir_emit() and updates ctx->pos on success;
this lets us convert bch2_readdir() to drop_locks_do().
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Combine iter/update/trigger/str_hash flags into a single enum, and
x-macroize them for a to_text() function later.
These flags are all for a specific iter/key/update context, so it makes
sense to group them together - iter/update/trigger flags were already
given distinct bits, this cleans up and unifies that handling.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Consolidate mark_superblock() and trans_mark_superblock(), like we did
with the other trigger paths.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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with errors_silent, reconstruct_alloc no longer requires fsck and
fix_errors to work
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Dead code
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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This optimization reduces the average number of comparisons required
from 2*n*log2(n) - 3*n + o(n) to n*log2(n) + 0.37*n + o(n). When n is
sufficiently large, it results in approximately 50% fewer comparisons.
Currently, eytzinger0_sort employs the textbook version of heapsort,
where during the heapify process, each level requires two comparisons
to determine the maximum among three elements. In contrast, the
bottom-up heapsort, during heapify, only compares two children at each
level until reaching a leaf node. Then, it backtracks from the leaf
node to find the correct position. Since heapify typically continues
until very close to the leaf node, the standard heapify requires about
2*log2(n) comparisons, while the bottom-up variant only needs log2(n)
comparisons.
The experimental data presented below is based on an array generated
by get_random_u32().
| N | comparisons(old) | comparisons(new) | time(old) | time(new) |
|-------|------------------|------------------|-----------|-----------|
| 10000 | 235381 | 136615 | 25545 us | 20366 us |
| 20000 | 510694 | 293425 | 31336 us | 18312 us |
| 30000 | 800384 | 457412 | 35042 us | 27386 us |
| 40000 | 1101617 | 626831 | 48779 us | 38253 us |
| 50000 | 1409762 | 799637 | 62238 us | 46950 us |
| 60000 | 1721191 | 974521 | 75588 us | 58367 us |
| 70000 | 2038536 | 1152171 | 90823 us | 68778 us |
| 80000 | 2362958 | 1333472 | 104165 us | 78625 us |
| 90000 | 2690900 | 1516065 | 116111 us | 89573 us |
| 100000| 3019413 | 1699879 | 133638 us | 100998 us |
Refs:
BOTTOM-UP-HEAPSORT, a new variant of HEAPSORT beating, on an average,
QUICKSORT (if n is not very small)
Ingo Wegener
Theoretical Computer Science, 118(1); Pages 81-98, 13 September 1993
https://doi.org/10.1016/0304-3975(93)90364-Y
Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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same leaf node
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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reading the journal can take a decent amount of time compared to the
rest of fsck, let's only read it when required.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Be more explicit to the user about what we're doing.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Long form version of bch2_btree_path_to_text() - useful in error
messages and tracepoints.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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small cleanup
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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debug helper
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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better btree node read path error messages
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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