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bcachefs: Improve trace_trans_restart_would_deadlock

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In the CI, we're seeing tests failing due to excessive would_deadlock
transaction restarts - the tracepoint now includes the lock cycle that
occured.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2023-05-26 16:59:07 -04:00
parent e153a0d70b
commit 3398124444
3 changed files with 28 additions and 7 deletions
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3
fs/bcachefs/btree_iter.c
View File

@ -3054,6 +3054,7 @@ void bch2_btree_trans_to_text(struct printbuf *out, struct btree_trans *trans)
struct btree_path *path;
struct btree_bkey_cached_common *b;
static char lock_types[] = { 'r', 'i', 'w' };
struct task_struct *task = READ_ONCE(trans->locking_wait.task);
unsigned l, idx;
if (!out->nr_tabstops) {
@ -3061,7 +3062,7 @@ void bch2_btree_trans_to_text(struct printbuf *out, struct btree_trans *trans)
printbuf_tabstop_push(out, 32);
}
prt_printf(out, "%i %s\n", trans->locking_wait.task->pid, trans->fn);
prt_printf(out, "%i %s\n", task ? task->pid : 0, trans->fn);
trans_for_each_path_safe(trans, path, idx) {
if (!path->nodes_locked)

25
fs/bcachefs/btree_locking.c
View File

@ -142,10 +142,28 @@ static bool lock_graph_remove_non_waiters(struct lock_graph *g)
return false;
}
static void trace_would_deadlock(struct lock_graph *g, struct btree_trans *trans,
unsigned long ip)
{
struct bch_fs *c = trans->c;
count_event(c, trans_restart_would_deadlock);
if (trace_trans_restart_would_deadlock_enabled()) {
struct printbuf buf = PRINTBUF;
buf.atomic++;
print_cycle(&buf, g);
trace_trans_restart_would_deadlock(trans, ip, buf.buf);
printbuf_exit(&buf);
}
}
static int abort_lock(struct lock_graph *g, struct trans_waiting_for_lock *i)
{
if (i == g->g) {
trace_and_count(i->trans->c, trans_restart_would_deadlock, i->trans, _RET_IP_);
trace_would_deadlock(g, i->trans, _RET_IP_);
return btree_trans_restart(i->trans, BCH_ERR_transaction_restart_would_deadlock);
} else {
i->trans->lock_must_abort = true;
@ -266,15 +284,16 @@ int bch2_check_for_deadlock(struct btree_trans *trans, struct printbuf *cycle)
unsigned path_idx;
int ret;
g.nr = 0;
if (trans->lock_must_abort) {
if (cycle)
return -1;
trace_and_count(trans->c, trans_restart_would_deadlock, trans, _RET_IP_);
trace_would_deadlock(&g, trans, _RET_IP_);
return btree_trans_restart(trans, BCH_ERR_transaction_restart_would_deadlock);
}
g.nr = 0;
lock_graph_down(&g, trans);
next:
if (!g.nr)

7
fs/bcachefs/trace.h
View File

@ -1205,10 +1205,11 @@ DEFINE_EVENT(transaction_restart_iter, trans_restart_memory_allocation_failure,
TP_ARGS(trans, caller_ip, path)
);
DEFINE_EVENT(transaction_event, trans_restart_would_deadlock,
DEFINE_EVENT(trans_str, trans_restart_would_deadlock,
TP_PROTO(struct btree_trans *trans,
unsigned long caller_ip),
TP_ARGS(trans, caller_ip)
unsigned long caller_ip,
const char *cycle),
TP_ARGS(trans, caller_ip, cycle)
);
DEFINE_EVENT(transaction_event, trans_restart_would_deadlock_recursion_limit,