Message ID | d9cfb7e7a23e60845e6fc6213ee34e77946849a6.1577999991.git.dennis@kernel.org (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | btrfs: async discard follow up | expand |
On Thu, Jan 02, 2020 at 04:26:35PM -0500, Dennis Zhou wrote: > An earlier patch keeps track of discardable_extents. These are > undiscarded extents managed by the free space cache. Here, we will use > this to dynamically calculate the discard delay interval. > > There are 3 rate to consider. The first is the target convergence rate, > the rate to discard all discardable_extents over the > BTRFS_DISCARD_TARGET_MSEC time frame. This is clamped by the lower > limit, the iops limit or BTRFS_DISCARD_MIN_DELAY (1ms), and the upper > limit, BTRFS_DISCARD_MAX_DELAY (1s). We reevaluate this delay every > transaction commit. > > Signed-off-by: Dennis Zhou <dennis@kernel.org> > Reviewed-by: Josef Bacik <josef@toxicpanda.com> > --- > fs/btrfs/ctree.h | 2 ++ > fs/btrfs/discard.c | 55 +++++++++++++++++++++++++++++++++++++++--- > fs/btrfs/discard.h | 1 + > fs/btrfs/extent-tree.c | 4 ++- > fs/btrfs/sysfs.c | 31 ++++++++++++++++++++++++ > 5 files changed, 88 insertions(+), 5 deletions(-) > > diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h > index 7c1c236d13ae..c73bbc7e4491 100644 > --- a/fs/btrfs/ctree.h > +++ b/fs/btrfs/ctree.h > @@ -468,6 +468,8 @@ struct btrfs_discard_ctl { > struct list_head discard_list[BTRFS_NR_DISCARD_LISTS]; > atomic_t discardable_extents; > atomic64_t discardable_bytes; > + unsigned long delay; > + unsigned iops_limit; As the kbps_limit uses u32, I switched that to u32 as well. > }; > > /* delayed seq elem */ > diff --git a/fs/btrfs/discard.c b/fs/btrfs/discard.c > index 173770bf8a2d..abcc3b2189d1 100644 > --- a/fs/btrfs/discard.c > +++ b/fs/btrfs/discard.c > @@ -15,6 +15,12 @@ > #define BTRFS_DISCARD_DELAY (120ULL * NSEC_PER_SEC) > #define BTRFS_DISCARD_UNUSED_DELAY (10ULL * NSEC_PER_SEC) > > +/* Target completion latency of discarding all discardable extents */ > +#define BTRFS_DISCARD_TARGET_MSEC (6 * 60 * 60UL * MSEC_PER_SEC) > +#define BTRFS_DISCARD_MIN_DELAY_MSEC (1UL) > +#define BTRFS_DISCARD_MAX_DELAY_MSEC (1000UL) > +#define BTRFS_DISCARD_MAX_IOPS (10U) > + > static struct list_head *get_discard_list(struct btrfs_discard_ctl *discard_ctl, > struct btrfs_block_group *block_group) > { > @@ -235,11 +241,18 @@ void btrfs_discard_schedule_work(struct btrfs_discard_ctl *discard_ctl, > > block_group = find_next_block_group(discard_ctl, now); > if (block_group) { > - u64 delay = 0; > + unsigned long delay = discard_ctl->delay; > + > + /* > + * This timeout is to hopefully prevent immediate discarding > + * in a recently allocated block group. > + */ > + if (now < block_group->discard_eligible_time) { > + u64 bg_timeout = (block_group->discard_eligible_time - > + now); > > - if (now < block_group->discard_eligible_time) > - delay = nsecs_to_jiffies( > - block_group->discard_eligible_time - now); > + delay = max(delay, nsecs_to_jiffies(bg_timeout)); > + } > > mod_delayed_work(discard_ctl->discard_workers, > &discard_ctl->work, delay); > @@ -342,6 +355,38 @@ bool btrfs_run_discard_work(struct btrfs_discard_ctl *discard_ctl) > test_bit(BTRFS_FS_DISCARD_RUNNING, &fs_info->flags)); > } > > +/** > + * btrfs_discard_calc_delay - recalculate the base delay > + * @discard_ctl: discard control > + * > + * Recalculate the base delay which is based off the total number of > + * discardable_extents. Clamp this between the lower_limit (iops_limit or 1ms) > + * and the upper_limit (BTRFS_DISCARD_MAX_DELAY_MSEC). > + */ > +void btrfs_discard_calc_delay(struct btrfs_discard_ctl *discard_ctl) > +{ > + s32 discardable_extents = > + atomic_read(&discard_ctl->discardable_extents); > + unsigned iops_limit; > + unsigned long delay, lower_limit = BTRFS_DISCARD_MIN_DELAY_MSEC; > + > + if (!discardable_extents) > + return; > + > + spin_lock(&discard_ctl->lock); > + > + iops_limit = READ_ONCE(discard_ctl->iops_limit); > + if (iops_limit) > + lower_limit = max_t(unsigned long, lower_limit, > + MSEC_PER_SEC / iops_limit); > + > + delay = BTRFS_DISCARD_TARGET_MSEC / discardable_extents; > + delay = clamp(delay, lower_limit, BTRFS_DISCARD_MAX_DELAY_MSEC); > + discard_ctl->delay = msecs_to_jiffies(delay); > + > + spin_unlock(&discard_ctl->lock); > +} > + > /** > * btrfs_discard_update_discardable - propagate discard counters > * @block_group: block_group of interest > @@ -464,6 +509,8 @@ void btrfs_discard_init(struct btrfs_fs_info *fs_info) > > atomic_set(&discard_ctl->discardable_extents, 0); > atomic64_set(&discard_ctl->discardable_bytes, 0); > + discard_ctl->delay = BTRFS_DISCARD_MAX_DELAY_MSEC; > + discard_ctl->iops_limit = BTRFS_DISCARD_MAX_IOPS; > } > > void btrfs_discard_cleanup(struct btrfs_fs_info *fs_info) > diff --git a/fs/btrfs/discard.h b/fs/btrfs/discard.h > index 0f2f89b1b0b9..5250fe178e49 100644 > --- a/fs/btrfs/discard.h > +++ b/fs/btrfs/discard.h > @@ -17,6 +17,7 @@ void btrfs_discard_schedule_work(struct btrfs_discard_ctl *discard_ctl, > bool btrfs_run_discard_work(struct btrfs_discard_ctl *discard_ctl); > > /* Update operations */ > +void btrfs_discard_calc_delay(struct btrfs_discard_ctl *discard_ctl); > void btrfs_discard_update_discardable(struct btrfs_block_group *block_group, > struct btrfs_free_space_ctl *ctl); > > diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c > index 2c12366cfde5..0163fdd59f8f 100644 > --- a/fs/btrfs/extent-tree.c > +++ b/fs/btrfs/extent-tree.c > @@ -2935,8 +2935,10 @@ int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans) > cond_resched(); > } > > - if (btrfs_test_opt(fs_info, DISCARD_ASYNC)) > + if (btrfs_test_opt(fs_info, DISCARD_ASYNC)) { > + btrfs_discard_calc_delay(&fs_info->discard_ctl); > btrfs_discard_schedule_work(&fs_info->discard_ctl, true); > + } > > /* > * Transaction is finished. We don't need the lock anymore. We > diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c > index e9dbdbbbebeb..e175aaf7a1e6 100644 > --- a/fs/btrfs/sysfs.c > +++ b/fs/btrfs/sysfs.c > @@ -344,6 +344,36 @@ static const struct attribute_group btrfs_static_feature_attr_group = { > */ > #define discard_to_fs_info(_kobj) to_fs_info((_kobj)->parent->parent) > > +static ssize_t btrfs_discard_iops_limit_show(struct kobject *kobj, > + struct kobj_attribute *a, > + char *buf) > +{ > + struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj); > + > + return snprintf(buf, PAGE_SIZE, "%u\n", > + READ_ONCE(fs_info->discard_ctl.iops_limit)); > +} > + > +static ssize_t btrfs_discard_iops_limit_store(struct kobject *kobj, > + struct kobj_attribute *a, > + const char *buf, size_t len) > +{ > + struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj); > + struct btrfs_discard_ctl *discard_ctl = &fs_info->discard_ctl; > + unsigned iops_limit; > + int ret; > + > + ret = kstrtouint(buf, 10, &iops_limit); > + if (ret) > + return -EINVAL; > + > + WRITE_ONCE(discard_ctl->iops_limit, iops_limit); > + > + return len; > +} > +BTRFS_ATTR_RW(discard, iops_limit, btrfs_discard_iops_limit_show, > + btrfs_discard_iops_limit_store); > + > static ssize_t btrfs_discardable_extents_show(struct kobject *kobj, > struct kobj_attribute *a, > char *buf) > @@ -367,6 +397,7 @@ static ssize_t btrfs_discardable_bytes_show(struct kobject *kobj, > BTRFS_ATTR(discard, discardable_bytes, btrfs_discardable_bytes_show); > > static const struct attribute *discard_debug_attrs[] = { > + BTRFS_ATTR_PTR(discard, iops_limit), > BTRFS_ATTR_PTR(discard, discardable_extents), > BTRFS_ATTR_PTR(discard, discardable_bytes), I've reordered the callbacks and definitions so they're in alphabetical order (in the base branch and in all the following patches).
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 7c1c236d13ae..c73bbc7e4491 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -468,6 +468,8 @@ struct btrfs_discard_ctl { struct list_head discard_list[BTRFS_NR_DISCARD_LISTS]; atomic_t discardable_extents; atomic64_t discardable_bytes; + unsigned long delay; + unsigned iops_limit; }; /* delayed seq elem */ diff --git a/fs/btrfs/discard.c b/fs/btrfs/discard.c index 173770bf8a2d..abcc3b2189d1 100644 --- a/fs/btrfs/discard.c +++ b/fs/btrfs/discard.c @@ -15,6 +15,12 @@ #define BTRFS_DISCARD_DELAY (120ULL * NSEC_PER_SEC) #define BTRFS_DISCARD_UNUSED_DELAY (10ULL * NSEC_PER_SEC) +/* Target completion latency of discarding all discardable extents */ +#define BTRFS_DISCARD_TARGET_MSEC (6 * 60 * 60UL * MSEC_PER_SEC) +#define BTRFS_DISCARD_MIN_DELAY_MSEC (1UL) +#define BTRFS_DISCARD_MAX_DELAY_MSEC (1000UL) +#define BTRFS_DISCARD_MAX_IOPS (10U) + static struct list_head *get_discard_list(struct btrfs_discard_ctl *discard_ctl, struct btrfs_block_group *block_group) { @@ -235,11 +241,18 @@ void btrfs_discard_schedule_work(struct btrfs_discard_ctl *discard_ctl, block_group = find_next_block_group(discard_ctl, now); if (block_group) { - u64 delay = 0; + unsigned long delay = discard_ctl->delay; + + /* + * This timeout is to hopefully prevent immediate discarding + * in a recently allocated block group. + */ + if (now < block_group->discard_eligible_time) { + u64 bg_timeout = (block_group->discard_eligible_time - + now); - if (now < block_group->discard_eligible_time) - delay = nsecs_to_jiffies( - block_group->discard_eligible_time - now); + delay = max(delay, nsecs_to_jiffies(bg_timeout)); + } mod_delayed_work(discard_ctl->discard_workers, &discard_ctl->work, delay); @@ -342,6 +355,38 @@ bool btrfs_run_discard_work(struct btrfs_discard_ctl *discard_ctl) test_bit(BTRFS_FS_DISCARD_RUNNING, &fs_info->flags)); } +/** + * btrfs_discard_calc_delay - recalculate the base delay + * @discard_ctl: discard control + * + * Recalculate the base delay which is based off the total number of + * discardable_extents. Clamp this between the lower_limit (iops_limit or 1ms) + * and the upper_limit (BTRFS_DISCARD_MAX_DELAY_MSEC). + */ +void btrfs_discard_calc_delay(struct btrfs_discard_ctl *discard_ctl) +{ + s32 discardable_extents = + atomic_read(&discard_ctl->discardable_extents); + unsigned iops_limit; + unsigned long delay, lower_limit = BTRFS_DISCARD_MIN_DELAY_MSEC; + + if (!discardable_extents) + return; + + spin_lock(&discard_ctl->lock); + + iops_limit = READ_ONCE(discard_ctl->iops_limit); + if (iops_limit) + lower_limit = max_t(unsigned long, lower_limit, + MSEC_PER_SEC / iops_limit); + + delay = BTRFS_DISCARD_TARGET_MSEC / discardable_extents; + delay = clamp(delay, lower_limit, BTRFS_DISCARD_MAX_DELAY_MSEC); + discard_ctl->delay = msecs_to_jiffies(delay); + + spin_unlock(&discard_ctl->lock); +} + /** * btrfs_discard_update_discardable - propagate discard counters * @block_group: block_group of interest @@ -464,6 +509,8 @@ void btrfs_discard_init(struct btrfs_fs_info *fs_info) atomic_set(&discard_ctl->discardable_extents, 0); atomic64_set(&discard_ctl->discardable_bytes, 0); + discard_ctl->delay = BTRFS_DISCARD_MAX_DELAY_MSEC; + discard_ctl->iops_limit = BTRFS_DISCARD_MAX_IOPS; } void btrfs_discard_cleanup(struct btrfs_fs_info *fs_info) diff --git a/fs/btrfs/discard.h b/fs/btrfs/discard.h index 0f2f89b1b0b9..5250fe178e49 100644 --- a/fs/btrfs/discard.h +++ b/fs/btrfs/discard.h @@ -17,6 +17,7 @@ void btrfs_discard_schedule_work(struct btrfs_discard_ctl *discard_ctl, bool btrfs_run_discard_work(struct btrfs_discard_ctl *discard_ctl); /* Update operations */ +void btrfs_discard_calc_delay(struct btrfs_discard_ctl *discard_ctl); void btrfs_discard_update_discardable(struct btrfs_block_group *block_group, struct btrfs_free_space_ctl *ctl); diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 2c12366cfde5..0163fdd59f8f 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -2935,8 +2935,10 @@ int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans) cond_resched(); } - if (btrfs_test_opt(fs_info, DISCARD_ASYNC)) + if (btrfs_test_opt(fs_info, DISCARD_ASYNC)) { + btrfs_discard_calc_delay(&fs_info->discard_ctl); btrfs_discard_schedule_work(&fs_info->discard_ctl, true); + } /* * Transaction is finished. We don't need the lock anymore. We diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c index e9dbdbbbebeb..e175aaf7a1e6 100644 --- a/fs/btrfs/sysfs.c +++ b/fs/btrfs/sysfs.c @@ -344,6 +344,36 @@ static const struct attribute_group btrfs_static_feature_attr_group = { */ #define discard_to_fs_info(_kobj) to_fs_info((_kobj)->parent->parent) +static ssize_t btrfs_discard_iops_limit_show(struct kobject *kobj, + struct kobj_attribute *a, + char *buf) +{ + struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj); + + return snprintf(buf, PAGE_SIZE, "%u\n", + READ_ONCE(fs_info->discard_ctl.iops_limit)); +} + +static ssize_t btrfs_discard_iops_limit_store(struct kobject *kobj, + struct kobj_attribute *a, + const char *buf, size_t len) +{ + struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj); + struct btrfs_discard_ctl *discard_ctl = &fs_info->discard_ctl; + unsigned iops_limit; + int ret; + + ret = kstrtouint(buf, 10, &iops_limit); + if (ret) + return -EINVAL; + + WRITE_ONCE(discard_ctl->iops_limit, iops_limit); + + return len; +} +BTRFS_ATTR_RW(discard, iops_limit, btrfs_discard_iops_limit_show, + btrfs_discard_iops_limit_store); + static ssize_t btrfs_discardable_extents_show(struct kobject *kobj, struct kobj_attribute *a, char *buf) @@ -367,6 +397,7 @@ static ssize_t btrfs_discardable_bytes_show(struct kobject *kobj, BTRFS_ATTR(discard, discardable_bytes, btrfs_discardable_bytes_show); static const struct attribute *discard_debug_attrs[] = { + BTRFS_ATTR_PTR(discard, iops_limit), BTRFS_ATTR_PTR(discard, discardable_extents), BTRFS_ATTR_PTR(discard, discardable_bytes), NULL,