* [PATCH v3 1/2] btrfs: Add the capability of getting commit stats in BTRFS
2022-06-21 21:52 [PATCH v3 0/2] btrfs: Expose BTRFS commit stats through sysfs Ioannis Angelakopoulos
@ 2022-06-21 21:52 ` Ioannis Angelakopoulos
2022-06-21 21:52 ` [PATCH v3 2/2] btrfs: Expose the BTRFS commit stats through sysfs Ioannis Angelakopoulos
1 sibling, 0 replies; 4+ messages in thread
From: Ioannis Angelakopoulos @ 2022-06-21 21:52 UTC (permalink / raw)
To: linux-btrfs, kernel-team
First we add "struct btrfs_commit_stats" data structure under "fs_info"
in fs/btrfs/ctree.h to store the commit stats for BTRFS that will be
exposed through sysfs.
The stats exposed are: 1) The number of commits so far, 2) The duration of
the last commit in ms, 3) The maximum commit duration seen so far in ms
and 4) The total duration for all commits so far in ms.
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.
Signed-off-by: Ioannis Angelakopoulos <iangelak@fb.com>
---
fs/btrfs/ctree.h | 14 ++++++++++++++
fs/btrfs/transaction.c | 22 ++++++++++++++++++++++
2 files changed, 36 insertions(+)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 1347c92234a5..2bd4a53c0046 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -667,6 +667,18 @@ enum btrfs_exclusive_operation {
BTRFS_EXCLOP_SWAP_ACTIVATE,
};
+/* Storing data about btrfs commits. The data are accessible over sysfs */
+struct btrfs_commit_stats {
+ /* Total number of commits */
+ u64 commit_counter;
+ /* The maximum commit duration so far*/
+ u64 max_commit_dur;
+ /* The last commit duration */
+ u64 last_commit_dur;
+ /* The total commit duration */
+ u64 total_commit_dur;
+};
+
struct btrfs_fs_info {
u8 chunk_tree_uuid[BTRFS_UUID_SIZE];
unsigned long flags;
@@ -1076,6 +1088,8 @@ struct btrfs_fs_info {
spinlock_t zone_active_bgs_lock;
struct list_head zone_active_bgs;
+ struct btrfs_commit_stats commit_stats;
+
#ifdef CONFIG_BTRFS_FS_REF_VERIFY
spinlock_t ref_verify_lock;
struct rb_root block_tree;
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 06c0a958d114..5b9451b3b005 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -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"
@@ -2084,12 +2085,23 @@ 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_counter++;
+ 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);
@@ -2214,6 +2226,12 @@ 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);
@@ -2455,6 +2473,8 @@ 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)
@@ -2462,6 +2482,8 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
kmem_cache_free(btrfs_trans_handle_cachep, trans);
+ update_commit_stats(fs_info, interval);
+
return ret;
unlock_reloc:
--
2.30.2
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH v3 2/2] btrfs: Expose the BTRFS commit stats through sysfs
2022-06-21 21:52 [PATCH v3 0/2] btrfs: Expose BTRFS commit stats through sysfs Ioannis Angelakopoulos
2022-06-21 21:52 ` [PATCH v3 1/2] btrfs: Add the capability of getting commit stats in BTRFS Ioannis Angelakopoulos
@ 2022-06-21 21:52 ` Ioannis Angelakopoulos
2022-06-22 6:32 ` kernel test robot
1 sibling, 1 reply; 4+ messages in thread
From: Ioannis Angelakopoulos @ 2022-06-21 21:52 UTC (permalink / raw)
To: linux-btrfs, kernel-team
Create a new sysfs entry named "commit_stats" under /sys/fs/btrfs/<UUID>/
for each mounted BTRFS filesystem. The entry exposes: 1) The number of
commits so far, 2) The duration of the last commit in ms, 3) The maximum
commit duration seen so far in ms and 4) The total duration for all commits
so far in ms.
The function "btrfs_commit_stats_show" in fs/btrfs/sysfs.c is responsible
for exposing the stats to user space.
The function "btrfs_commit_stats_store" in fs/btrfs/sysfs.c is responsible
for resetting the maximum commit duration to zero. This benefits
applications that want to sample the maximum commit duration over a long
time period. Only the maximum commit duration is reset to zero in order to
avoid loss of data if multiple threads are trying to reset the commit stats
data at the same time.
Signed-off-by: Ioannis Angelakopoulos <iangelak@fb.com>
---
fs/btrfs/sysfs.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 45 insertions(+)
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index db3736de14a5..0e13daa1a466 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -10,6 +10,7 @@
#include <linux/completion.h>
#include <linux/bug.h>
#include <crypto/hash.h>
+#include <linux/math64.h>
#include "ctree.h"
#include "discard.h"
@@ -991,6 +992,49 @@ static ssize_t btrfs_sectorsize_show(struct kobject *kobj,
BTRFS_ATTR(, sectorsize, btrfs_sectorsize_show);
+static ssize_t btrfs_commit_stats_show(struct kobject *kobj,
+ struct kobj_attribute *a, char *buf)
+{
+ struct btrfs_fs_info *fs_info = to_fs_info(kobj);
+
+ return sysfs_emit(buf,
+ "commits %llu\n"
+ "last_commit_dur_ms %llu\n"
+ "max_commit_dur_ms %llu\n"
+ "total_commit_dur_ms %llu\n",
+ fs_info->commit_stats.commit_counter,
+ div_u64(fs_info->commit_stats.last_commit_dur / NSEC_PER_MSEC),
+ div_u64(fs_info->commit_stats.max_commit_dur / NSEC_PER_MSEC),
+ div_u64(fs_info->commit_stats.total_commit_dur / NSEC_PER_MSEC));
+}
+
+static ssize_t btrfs_commit_stats_store(struct kobject *kobj,
+ struct kobj_attribute *a,
+ const char *buf, size_t len)
+{
+ struct btrfs_fs_info *fs_info = to_fs_info(kobj);
+ unsigned long val;
+ int ret;
+
+ if (!fs_info)
+ return -EPERM;
+
+ if (!capable(CAP_SYS_RESOURCE))
+ return -EPERM;
+
+ ret = kstrtoul(buf, 10, &val);
+ if (ret)
+ return ret;
+ if (val)
+ return -EINVAL;
+
+ fs_info->commit_stats.max_commit_dur = 0;
+
+ return len;
+}
+BTRFS_ATTR_RW(, commit_stats, btrfs_commit_stats_show,
+ btrfs_commit_stats_store);
+
static ssize_t btrfs_clone_alignment_show(struct kobject *kobj,
struct kobj_attribute *a, char *buf)
{
@@ -1230,6 +1274,7 @@ static const struct attribute *btrfs_attrs[] = {
BTRFS_ATTR_PTR(, generation),
BTRFS_ATTR_PTR(, read_policy),
BTRFS_ATTR_PTR(, bg_reclaim_threshold),
+ BTRFS_ATTR_PTR(, commit_stats),
NULL,
};
--
2.30.2
^ permalink raw reply related [flat|nested] 4+ messages in thread