From: Zhang Yi <yi.zhang@xxxxxxxxxx>
journal_clean_one_cp_list() has been merged into
journal_shrink_one_cp_list(), but do chekpoint buffer cleanup from the
committing process is just a best effort, it should stop scan once it
meet a busy buffer, or else it will cause a lot of invalid buffer scan
and checks. We catch a performance regression when doing fs_mark tests
below.
Test cmd:
./fs_mark -d scratch -s 1024 -n 10000 -t 1 -D 100 -N 100
Before merging checkpoint buffer cleanup:
FSUse% Count Size Files/sec App Overhead
95 10000 1024 8304.9 49033
After merging checkpoint buffer cleanup:
FSUse% Count Size Files/sec App Overhead
95 10000 1024 7649.0 50012
FSUse% Count Size Files/sec App Overhead
95 10000 1024 2107.1 50871
After merging checkpoint buffer cleanup, the total loop count in
journal_shrink_one_cp_list() could be up to 6,261,600+ (50,000+ ~
100,000+ in general), most of them are invalid. This patch fix it
through passing 'shrink_type' into journal_shrink_one_cp_list() and add
a new 'SHRINK_BUSY_STOP' to indicate it should stop once meet a busy
buffer. After fix, the loop count descending back to 10,000+.
After this fix:
FSUse% Count Size Files/sec App Overhead
95 10000 1024 8558.4 49109
Fixes: b98dba273a0e ("jbd2: remove journal_clean_one_cp_list()")
Signed-off-by: Zhang Yi <yi.zhang@xxxxxxxxxx>
---
fs/jbd2/checkpoint.c | 20 ++++++++++++++------
1 file changed, 14 insertions(+), 6 deletions(-)
diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c
index 9ec91017a7f3..936c6d758a65 100644
--- a/fs/jbd2/checkpoint.c
+++ b/fs/jbd2/checkpoint.c
@@ -349,6 +349,8 @@ int jbd2_cleanup_journal_tail(journal_t *journal)
/* Checkpoint list management */
+enum shrink_type {SHRINK_DESTROY, SHRINK_BUSY_STOP, SHRINK_BUSY_SKIP};
+
/*
* journal_shrink_one_cp_list
*
@@ -360,7 +362,8 @@ int jbd2_cleanup_journal_tail(journal_t *journal)
* Called with j_list_lock held.
*/
static unsigned long journal_shrink_one_cp_list(struct journal_head *jh,
- bool destroy, bool *released)
+ enum shrink_type type,
+ bool *released)
{
struct journal_head *last_jh;
struct journal_head *next_jh = jh;
@@ -376,12 +379,15 @@ static unsigned long journal_shrink_one_cp_list(struct journal_head *jh,
jh = next_jh;
next_jh = jh->b_cpnext;
- if (destroy) {
+ if (type == SHRINK_DESTROY) {
ret = __jbd2_journal_remove_checkpoint(jh);
} else {
ret = jbd2_journal_try_remove_checkpoint(jh);
- if (ret < 0)
- continue;
+ if (ret < 0) {
+ if (type == SHRINK_BUSY_SKIP)
+ continue;
+ break;
+ }
}
nr_freed++;
@@ -445,7 +451,7 @@ unsigned long jbd2_journal_shrink_checkpoint_list(journal_t *journal,
tid = transaction->t_tid;
freed = journal_shrink_one_cp_list(transaction->t_checkpoint_list,
- false, &released);
+ SHRINK_BUSY_SKIP, &released);
nr_freed += freed;
(*nr_to_scan) -= min(*nr_to_scan, freed);
if (*nr_to_scan == 0)
@@ -485,19 +491,21 @@ unsigned long jbd2_journal_shrink_checkpoint_list(journal_t *journal,
void __jbd2_journal_clean_checkpoint_list(journal_t *journal, bool destroy)
{
transaction_t *transaction, *last_transaction, *next_transaction;
+ enum shrink_type type;
bool released;
transaction = journal->j_checkpoint_transactions;
if (!transaction)
return;
+ type = destroy ? SHRINK_DESTROY : SHRINK_BUSY_STOP;
last_transaction = transaction->t_cpprev;
next_transaction = transaction;
do {
transaction = next_transaction;
next_transaction = transaction->t_cpnext;
journal_shrink_one_cp_list(transaction->t_checkpoint_list,
- destroy, &released);
+ type, &released);
/*
* This function only frees up some memory if possible so we
* dont have an obligation to finish processing. Bail out if
--
2.39.2
