| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Date: Mon, 12 Dec 2022 14:47:15 -0800
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <chao@...nel.org>
Cc: Yangtao Li <frank.li@...o.com>,
linux-f2fs-devel@...ts.sourceforge.net,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] f2fs: add support for counting time of submit discard
cmd
On 12/12, Chao Yu wrote:
> On 2022/12/12 20:51, Yangtao Li wrote:
> > This patch adds support for counting the average time and
> > peak time of submit discard command, and we can see its
> > value in debugfs.
> >
> > It is not sure whether the block layer has recorded these
> > data, and these data are allowed to be accessed by fs,
> > or they are only exported to user space.
> >
> > On the one hand, I added these data to better understand
> > the current device operating status, and to further control
> > the discard process in a more detailed manner based on the
> > discard submit time in the future.
>
> Again, w'd better to consider this functionality only when DEBUG_FS is
> enabled.
BTW, why can't we use iostat to get the discard latencies?
>
> >
> > Signed-off-by: Yangtao Li <frank.li@...o.com>
> > ---
> > fs/f2fs/debug.c | 10 +++++++---
> > fs/f2fs/f2fs.h | 6 ++++++
> > fs/f2fs/segment.c | 21 +++++++++++++++++++--
> > 3 files changed, 32 insertions(+), 5 deletions(-)
> >
> > diff --git a/fs/f2fs/debug.c b/fs/f2fs/debug.c
> > index 32af4f0c5735..142c256b89d9 100644
> > --- a/fs/f2fs/debug.c
> > +++ b/fs/f2fs/debug.c
> > @@ -120,6 +120,10 @@ 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->discard_peak = dcc->discard_time_peak;
> > si->nr_discarded =
> > atomic_read(&SM_I(sbi)->dcc_info->issued_discard);
> > si->nr_discarding =
> > @@ -545,9 +549,9 @@ 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,
> > - si->nr_discard_cmd, si->undiscard_blks);
> > + seq_printf(s, "Discard: (%4d %4d, avg:%4lldns, peak:%4lldns)) cmd: %4d undiscard:%4u\n",
> > + si->nr_discarding, si->nr_discarded, ktime_to_us(si->discard_avg),
> > + ktime_to_us(si->discard_peak), si->nr_discard_cmd, si->undiscard_blks);
> > seq_printf(s, " - atomic IO: %4d (Max. %4d)\n",
> > si->aw_cnt, si->max_aw_cnt);
> > seq_printf(s, " - compress: %4d, hit:%8d\n", si->compress_pages, si->compress_page_hit);
> > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> > index e8953c3dc81a..2cd55cb981ff 100644
> > --- a/fs/f2fs/f2fs.h
> > +++ b/fs/f2fs/f2fs.h
> > @@ -371,6 +371,8 @@ 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 {
> > @@ -415,6 +417,9 @@ 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 */
> > + ktime_t discard_time_peak; /* issued discard cmd peak time */
> > atomic_t issued_discard; /* # of issued discard */
> > atomic_t queued_discard; /* # of queued discard */
> > atomic_t discard_cmd_cnt; /* # of cached cmd count */
> > @@ -3896,6 +3901,7 @@ 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, discard_peak;
> > 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 a9099a754dd2..73cd05bb3f4a 100644
> > --- a/fs/f2fs/segment.c
> > +++ b/fs/f2fs/segment.c
> > @@ -937,6 +937,7 @@ 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;
> > @@ -1006,9 +1007,13 @@ 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--;
> > @@ -1018,6 +1023,16 @@ 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);
> > + if (dcc->discard_time_avg > dcc->discard_time_peak)
> > + dcc->discard_time_peak = dcc->discard_time_avg;
> > + atomic_inc(&dcc->issued_discard);
> > + spin_unlock_irqrestore(&dcc->discard_time_lock, flags);
>
> Why not calculating average time only in update_general_status()? and here,
> we just need to account total_{discard_time, discard_count} w/o additional
> spinlock.
>
> Thanks,
>
> > }
> > static void __check_sit_bitmap(struct f2fs_sb_info *sbi,
> > @@ -1166,6 +1181,7 @@ 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
> > @@ -1185,8 +1201,6 @@ 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, len * F2FS_BLKSIZE);
> > lstart += len;
> > @@ -2079,9 +2093,12 @@ 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->discard_time_peak = 0;
> > dcc->nr_discards = 0;
> > dcc->max_discards = MAIN_SEGS(sbi) << sbi->log_blocks_per_seg;
> > dcc->max_discard_request = DEF_MAX_DISCARD_REQUEST;
Powered by blists - more mailing lists