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 <dennis@xxxxxxxxxx>
---
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
