On 2022/11/29 12:15, Yangtao Li wrote:
This patch adds support for counting the average time of submit discard
command, and we can see its value in debugfs.

How about enabling this only when CONFIG_DEBUG_FS is on?

+Cc block mailing list

Not sure block layer has similar stats? if it hasn't, can such stat
be accounted in block layer, and then all filesystem can be benefited.

Thanks,


Signed-off-by: Yangtao Li <frank...@vivo.com>
---
  fs/f2fs/debug.c   |  7 +++++--
  fs/f2fs/f2fs.h    |  5 +++++
  fs/f2fs/segment.c | 18 ++++++++++++++++--
  3 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/fs/f2fs/debug.c b/fs/f2fs/debug.c
index 733b1bd37404..eed3edfc5faf 100644
--- a/fs/f2fs/debug.c
+++ b/fs/f2fs/debug.c
@@ -109,6 +109,9 @@ static void update_general_status(struct f2fs_sb_info *sbi)
                        llist_empty(&SM_I(sbi)->fcc_info->issue_list);
        }
        if (SM_I(sbi)->dcc_info) {
+               struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
+
+               si->discard_avg = dcc->discard_time_avg;
                si->nr_discarded =
                        atomic_read(&SM_I(sbi)->dcc_info->issued_discard);
                si->nr_discarding =
@@ -510,8 +513,8 @@ static int stat_show(struct seq_file *s, void *v)
                           si->nr_wb_cp_data, si->nr_wb_data,
                           si->nr_flushing, si->nr_flushed,
                           si->flush_list_empty);
-               seq_printf(s, "Discard: (%4d %4d)) cmd: %4d undiscard:%4u\n",
-                          si->nr_discarding, si->nr_discarded,
+               seq_printf(s, "Discard: (%4d %4d, avg:%4lldns)) cmd: %4d 
undiscard:%4u\n",
+                          si->nr_discarding, si->nr_discarded, 
ktime_to_us(si->discard_avg),
                           si->nr_discard_cmd, si->undiscard_blks);
                seq_printf(s, "  - atomic IO: %4d (Max. %4d)\n",
                           si->aw_cnt, si->max_aw_cnt);
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index eb8c27c4e5fc..5a99759d10ac 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -370,6 +370,8 @@ struct discard_cmd {
        int error;                      /* bio error */
        spinlock_t lock;                /* for state/bio_ref updating */
        unsigned short bio_ref;         /* bio reference count */
+       struct discard_cmd_control *dcc; /* global discard cmd control */
+       ktime_t submit_start;           /* submit start time */
  };
enum {
@@ -414,6 +416,8 @@ struct discard_cmd_control {
        unsigned int max_ordered_discard;       /* maximum discard granularity 
issued by lba order */
        unsigned int undiscard_blks;            /* # of undiscard blocks */
        unsigned int next_pos;                  /* next discard position */
+       spinlock_t discard_time_lock;   /* for discard time statistics */
+       ktime_t discard_time_avg;               /* issued discard cmd avg time 
*/
        atomic_t issued_discard;                /* # of issued discard */
        atomic_t queued_discard;                /* # of queued discard */
        atomic_t discard_cmd_cnt;               /* # of cached cmd count */
@@ -3882,6 +3886,7 @@ struct f2fs_stat_info {
        int nr_dio_read, nr_dio_write;
        unsigned int io_skip_bggc, other_skip_bggc;
        int nr_flushing, nr_flushed, flush_list_empty;
+       ktime_t discard_avg;
        int nr_discarding, nr_discarded;
        int nr_discard_cmd;
        unsigned int undiscard_blks;
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 9486ca49ecb1..bc96b1afb308 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -931,6 +931,7 @@ static struct discard_cmd *__create_discard_cmd(struct 
f2fs_sb_info *sbi,
        list_add_tail(&dc->list, pend_list);
        spin_lock_init(&dc->lock);
        dc->bio_ref = 0;
+       dc->dcc = dcc;
        atomic_inc(&dcc->discard_cmd_cnt);
        dcc->undiscard_blks += len;
@@ -1000,9 +1001,13 @@ static void __remove_discard_cmd(struct f2fs_sb_info *sbi,
  static void f2fs_submit_discard_endio(struct bio *bio)
  {
        struct discard_cmd *dc = (struct discard_cmd *)bio->bi_private;
+       struct discard_cmd_control *dcc = dc->dcc;
        unsigned long flags;
+       ktime_t submit_time;
+       int nr_discarded;
spin_lock_irqsave(&dc->lock, flags);
+       submit_time = ktime_sub(ktime_get(), dc->submit_start);
        if (!dc->error)
                dc->error = blk_status_to_errno(bio->bi_status);
        dc->bio_ref--;
@@ -1012,6 +1017,14 @@ static void f2fs_submit_discard_endio(struct bio *bio)
        }
        spin_unlock_irqrestore(&dc->lock, flags);
        bio_put(bio);
+
+       spin_lock_irqsave(&dcc->discard_time_lock, flags);
+       nr_discarded = atomic_read(&dcc->issued_discard);
+       dcc->discard_time_avg = div_u64(ktime_add(nr_discarded * 
dcc->discard_time_avg,
+                                                                               
submit_time),
+                                                                       
nr_discarded + 1);
+       atomic_inc(&dcc->issued_discard);
+       spin_unlock_irqrestore(&dcc->discard_time_lock, flags);
  }
static void __check_sit_bitmap(struct f2fs_sb_info *sbi,
@@ -1160,6 +1173,7 @@ static int __submit_discard_cmd(struct f2fs_sb_info *sbi,
                 * right away
                 */
                spin_lock_irqsave(&dc->lock, flags);
+               dc->submit_start = ktime_get();
                if (last)
                        dc->state = D_SUBMIT;
                else
@@ -1179,8 +1193,6 @@ static int __submit_discard_cmd(struct f2fs_sb_info *sbi,
                bio->bi_opf |= flag;
                submit_bio(bio);
- atomic_inc(&dcc->issued_discard);
-
                f2fs_update_iostat(sbi, NULL, FS_DISCARD, 1);
lstart += len;
@@ -2070,9 +2082,11 @@ static int create_discard_cmd_control(struct 
f2fs_sb_info *sbi)
        INIT_LIST_HEAD(&dcc->wait_list);
        INIT_LIST_HEAD(&dcc->fstrim_list);
        mutex_init(&dcc->cmd_lock);
+       spin_lock_init(&dcc->discard_time_lock);
        atomic_set(&dcc->issued_discard, 0);
        atomic_set(&dcc->queued_discard, 0);
        atomic_set(&dcc->discard_cmd_cnt, 0);
+       dcc->discard_time_avg = 0;
        dcc->nr_discards = 0;
        dcc->max_discards = MAIN_SEGS(sbi) << sbi->log_blocks_per_seg;
        dcc->max_discard_request = DEF_MAX_DISCARD_REQUEST;


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