kevin/linux
1
Fork 0
Code

bcachefs: Switch to local_clock() for fastpath time source

Browse Source 
local_clock() isn't always completely accurate - e.g. on machines with
TSC drift - but ktime_get_ns() overhead is too high, unfortunately.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2022-10-15 01:03:14 -04:00
parent fe5b37f699
commit d7e4e51370
2 changed files with 6 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
fs/bcachefs/btree_iter.c
View File

@ -2787,7 +2787,7 @@ u32 bch2_trans_begin(struct btree_trans *trans)
if (!trans->restarted &&
(need_resched() ||
ktime_get_ns() - trans->last_begin_time > BTREE_TRANS_MAX_LOCK_HOLD_TIME_NS)) {
local_clock() - trans->last_begin_time > BTREE_TRANS_MAX_LOCK_HOLD_TIME_NS)) {
bch2_trans_unlock(trans);
cond_resched();
bch2_trans_relock(trans);
@ -2797,7 +2797,7 @@ u32 bch2_trans_begin(struct btree_trans *trans)
if (trans->restarted)
bch2_btree_path_traverse_all(trans);
trans->last_begin_time = ktime_get_ns();
trans->last_begin_time = local_clock();
return trans->restart_count;
}
@ -2851,7 +2851,7 @@ void __bch2_trans_init(struct btree_trans *trans, struct bch_fs *c, const char *
memset(trans, 0, sizeof(*trans));
trans->c = c;
trans->fn = fn;
trans->last_begin_time = ktime_get_ns();
trans->last_begin_time = local_clock();
trans->fn_idx = bch2_trans_get_fn_idx(trans, c, fn);
trans->locking_wait.task = current;
trans->journal_replay_not_finished =

6
fs/bcachefs/btree_locking.h
View File

@ -87,7 +87,7 @@ static inline void mark_btree_node_locked(struct btree_trans *trans,
{
mark_btree_node_locked_noreset(path, level, type);
#ifdef CONFIG_BCACHEFS_LOCK_TIME_STATS
path->l[level].lock_taken_time = ktime_get_ns();
path->l[level].lock_taken_time = local_clock();
#endif
}
@ -119,7 +119,7 @@ static void btree_trans_lock_hold_time_update(struct btree_trans *trans,
if (s)
__bch2_time_stats_update(&s->lock_hold_times,
path->l[level].lock_taken_time,
ktime_get_ns());
local_clock());
#endif
}
@ -259,7 +259,7 @@ static inline int btree_node_lock(struct btree_trans *trans,
btree_node_lock_increment(trans, b, level, type) ||
!(ret = btree_node_lock_nopath(trans, b, type))) {
#ifdef CONFIG_BCACHEFS_LOCK_TIME_STATS
path->l[b->level].lock_taken_time = ktime_get_ns();
path->l[b->level].lock_taken_time = local_clock();
#endif
}