#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)
{
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);
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;
+ u32 iops_limit;
+ unsigned long delay;
+ unsigned long lower_limit = BTRFS_DISCARD_MIN_DELAY_MSEC;
+
+ discardable_extents = atomic_read(&discard_ctl->discardable_extents);
+ 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
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)
}
BTRFS_ATTR(discard, discardable_extents, btrfs_discardable_extents_show);
+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;
+ u32 iops_limit;
+ int ret;
+
+ ret = kstrtou32(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 const struct attribute *discard_debug_attrs[] = {
BTRFS_ATTR_PTR(discard, discardable_bytes),
BTRFS_ATTR_PTR(discard, discardable_extents),
+ BTRFS_ATTR_PTR(discard, iops_limit),
NULL,
};