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jbd2: fix checkpoint cleanup performance regression 

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

Cc: stable@kernel.org
Fixes: b98dba273a ("jbd2: remove journal_clean_one_cp_list()")
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230714025528.564988-2-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Zhang Yi 2023-07-14 10:55:26 +08:00 committed by Theodore Ts'o
parent 4eea9fbed9
commit 373ac52179
1 changed files with 14 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
fs/jbd2/checkpoint.c
View File

@ -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 @@ again:
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 @@ out:
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