Skip to content

Commit

Permalink
btrfs: collect commit stats, count, duration
Browse files Browse the repository at this point in the history
Track several stats about transaction commit, to be later exported via
sysfs:

- number of commits so far
- duration of the last commit in ns
- maximum commit duration seen so far in ns
- total duration for all commits so far in ns

The update of the commit stats occurs after the commit thread has gone
through all the logic that checks if there is another thread committing
at the same time. This means that we only account for actual commit work
in the commit stats we report and not the time the thread spends waiting
until it is ready to do the commit work.

Reviewed-by: Nikolay Borisov <[email protected]>
Signed-off-by: Ioannis Angelakopoulos <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>
  • Loading branch information
Ioannis Angelakopoulos authored and kdave committed Jul 25, 2022
1 parent f3e90c1 commit e55958c
Show file tree
Hide file tree
Showing 2 changed files with 37 additions and 0 deletions.
15 changes: 15 additions & 0 deletions fs/btrfs/ctree.h
Original file line number Diff line number Diff line change
Expand Up @@ -667,6 +667,18 @@ enum btrfs_exclusive_operation {
BTRFS_EXCLOP_SWAP_ACTIVATE,
};

/* Store data about transaction commits, exported via sysfs. */
struct btrfs_commit_stats {
/* Total number of commits */
u64 commit_count;
/* The maximum commit duration so far in ns */
u64 max_commit_dur;
/* The last commit duration in ns */
u64 last_commit_dur;
/* The total commit duration in ns */
u64 total_commit_dur;
};

struct btrfs_fs_info {
u8 chunk_tree_uuid[BTRFS_UUID_SIZE];
unsigned long flags;
Expand Down Expand Up @@ -1075,6 +1087,9 @@ struct btrfs_fs_info {
spinlock_t zone_active_bgs_lock;
struct list_head zone_active_bgs;

/* Updates are not protected by any lock */
struct btrfs_commit_stats commit_stats;

#ifdef CONFIG_BTRFS_FS_REF_VERIFY
spinlock_t ref_verify_lock;
struct rb_root block_tree;
Expand Down
22 changes: 22 additions & 0 deletions fs/btrfs/transaction.c
Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,7 @@
#include <linux/pagemap.h>
#include <linux/blkdev.h>
#include <linux/uuid.h>
#include <linux/timekeeping.h>
#include "misc.h"
#include "ctree.h"
#include "disk-io.h"
Expand Down Expand Up @@ -2098,12 +2099,23 @@ static void add_pending_snapshot(struct btrfs_trans_handle *trans)
list_add(&trans->pending_snapshot->list, &cur_trans->pending_snapshots);
}

static void update_commit_stats(struct btrfs_fs_info *fs_info, ktime_t interval)
{
fs_info->commit_stats.commit_count++;
fs_info->commit_stats.last_commit_dur = interval;
fs_info->commit_stats.max_commit_dur =
max_t(u64, fs_info->commit_stats.max_commit_dur, interval);
fs_info->commit_stats.total_commit_dur += interval;
}

int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_transaction *cur_trans = trans->transaction;
struct btrfs_transaction *prev_trans = NULL;
int ret;
ktime_t start_time;
ktime_t interval;

ASSERT(refcount_read(&trans->use_count) == 1);

Expand Down Expand Up @@ -2228,6 +2240,12 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
}
}

/*
* Get the time spent on the work done by the commit thread and not
* the time spent waiting on a previous commit
*/
start_time = ktime_get_ns();

extwriter_counter_dec(cur_trans, trans->type);

ret = btrfs_start_delalloc_flush(fs_info);
Expand Down Expand Up @@ -2469,13 +2487,17 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)

trace_btrfs_transaction_commit(fs_info);

interval = ktime_get_ns() - start_time;

btrfs_scrub_continue(fs_info);

if (current->journal_info == trans)
current->journal_info = NULL;

kmem_cache_free(btrfs_trans_handle_cachep, trans);

update_commit_stats(fs_info, interval);

return ret;

unlock_reloc:
Expand Down

0 comments on commit e55958c

Please sign in to comment.