Use the number of discardable extents to help guide our discard delay interval. This value is reevaluated every transaction commit.
Signed-off-by: Dennis Zhou <[email protected]> --- fs/btrfs/ctree.h | 2 ++ fs/btrfs/discard.c | 31 +++++++++++++++++++++++++++++-- fs/btrfs/discard.h | 3 +++ fs/btrfs/extent-tree.c | 4 +++- fs/btrfs/sysfs.c | 30 ++++++++++++++++++++++++++++++ 5 files changed, 67 insertions(+), 3 deletions(-) diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 8479ab037812..b0823961d049 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -449,6 +449,8 @@ struct btrfs_discard_ctl { struct list_head discard_list[BTRFS_NR_DISCARD_LISTS]; atomic_t discard_extents; atomic64_t discardable_bytes; + atomic_t delay; + atomic_t iops_limit; }; /* delayed seq elem */ diff --git a/fs/btrfs/discard.c b/fs/btrfs/discard.c index 75a2ff14b3c0..c7afb5f8240d 100644 --- a/fs/btrfs/discard.c +++ b/fs/btrfs/discard.c @@ -15,6 +15,11 @@ #define BTRFS_DISCARD_DELAY (300ULL * NSEC_PER_SEC) +/* target discard delay in milliseconds */ +#define BTRFS_DISCARD_TARGET_MSEC (6 * 60 * 60ULL * MSEC_PER_SEC) +#define BTRFS_DISCARD_MAX_DELAY (10000UL) +#define BTRFS_DISCARD_MAX_IOPS (10UL) + static struct list_head * btrfs_get_discard_list(struct btrfs_discard_ctl *discard_ctl, struct btrfs_block_group_cache *cache) @@ -170,10 +175,12 @@ void btrfs_discard_schedule_work(struct btrfs_discard_ctl *discard_ctl, cache = find_next_cache(discard_ctl, now); if (cache) { - u64 delay = 0; + u64 delay = atomic_read(&discard_ctl->delay); if (now < cache->discard_delay) - delay = nsecs_to_jiffies(cache->discard_delay - now); + delay = max_t(u64, delay, + nsecs_to_jiffies(cache->discard_delay - + now)); mod_delayed_work(discard_ctl->discard_workers, &discard_ctl->work, @@ -232,6 +239,24 @@ static void btrfs_discard_workfn(struct work_struct *work) btrfs_discard_schedule_work(discard_ctl, false); } +void btrfs_discard_calc_delay(struct btrfs_discard_ctl *discard_ctl) +{ + s32 discard_extents = atomic_read(&discard_ctl->discard_extents); + s32 iops_limit; + unsigned long delay; + + if (!discard_extents) + return; + + iops_limit = atomic_read(&discard_ctl->iops_limit); + if (iops_limit) + iops_limit = MSEC_PER_SEC / iops_limit; + + delay = BTRFS_DISCARD_TARGET_MSEC / discard_extents; + delay = clamp_t(s32, delay, iops_limit, BTRFS_DISCARD_MAX_DELAY); + atomic_set(&discard_ctl->delay, msecs_to_jiffies(delay)); +} + void btrfs_discard_punt_unused_bgs_list(struct btrfs_fs_info *fs_info) { struct btrfs_block_group_cache *cache, *next; @@ -301,6 +326,8 @@ void btrfs_discard_init(struct btrfs_fs_info *fs_info) atomic_set(&discard_ctl->discard_extents, 0); atomic64_set(&discard_ctl->discardable_bytes, 0); + atomic_set(&discard_ctl->delay, BTRFS_DISCARD_MAX_DELAY); + atomic_set(&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 d55a9a9f8ad8..acaf56f63b1c 100644 --- a/fs/btrfs/discard.h +++ b/fs/btrfs/discard.h @@ -7,6 +7,8 @@ #define BTRFS_DISCARD_H #include <linux/kernel.h> +#include <linux/jiffies.h> +#include <linux/time.h> #include <linux/workqueue.h> #include "ctree.h" @@ -39,6 +41,7 @@ void btrfs_discard_cancel_work(struct btrfs_discard_ctl *discard_ctl, struct btrfs_block_group_cache *cache); void btrfs_discard_schedule_work(struct btrfs_discard_ctl *discard_ctl, bool override); +void btrfs_discard_calc_delay(struct btrfs_discard_ctl *discard_ctl); void btrfs_discard_resume(struct btrfs_fs_info *fs_info); void btrfs_discard_stop(struct btrfs_fs_info *fs_info); void btrfs_discard_init(struct btrfs_fs_info *fs_info); diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index ff42e4abb01d..ab0d46da3771 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -2920,8 +2920,10 @@ 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 a2852706ec6c..b9a62e470316 100644 --- a/fs/btrfs/sysfs.c +++ b/fs/btrfs/sysfs.c @@ -493,9 +493,39 @@ static ssize_t btrfs_discardable_bytes_show(struct kobject *kobj, } BTRFS_ATTR(discard, discardable_bytes, btrfs_discardable_bytes_show); +static ssize_t btrfs_discard_iops_limit_show(struct kobject *kobj, + struct kobj_attribute *a, + char *buf) +{ + struct btrfs_fs_info *fs_info = to_fs_info(kobj->parent); + + return snprintf(buf, PAGE_SIZE, "%d\n", + atomic_read(&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 = to_fs_info(kobj->parent); + s32 iops_limit; + int ret; + + ret = kstrtos32(buf, 10, &iops_limit); + if (ret || iops_limit < 0) + return -EINVAL; + + atomic_set(&fs_info->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 const struct attribute *discard_attrs[] = { BTRFS_ATTR_PTR(discard, discard_extents), BTRFS_ATTR_PTR(discard, discardable_bytes), + BTRFS_ATTR_PTR(discard, iops_limit), NULL, }; -- 2.17.1
