[10/19] btrfs: calculate discard delay based on number of extents
diff mbox series

Message ID 37690bf17c3b3c9f20137fb186c7af4021bb664b.1570479299.git.dennis@kernel.org
State New
Headers show
Series
  • btrfs: async discard support
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Commit Message

Dennis Zhou Oct. 7, 2019, 8:17 p.m. UTC
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@kernel.org>
---
 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(-)

Comments

Josef Bacik Oct. 10, 2019, 3:41 p.m. UTC | #1
On Mon, Oct 07, 2019 at 04:17:41PM -0400, Dennis Zhou wrote:
> 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@kernel.org>
> ---
>  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));

Small nit, instead

			delay = nsecs_to_jiffies(cache->discard_delay - now);
			delay = max_t(u64, delay,
				      atomic_read(&discard_ctl->delay);

Looks a little cleaner.  Otherwise

Reviewed-by: Josef Bacik <josef@toxicpanda.com>

Thanks,

Josef
Dennis Zhou Oct. 11, 2019, 6:07 p.m. UTC | #2
On Thu, Oct 10, 2019 at 11:41:33AM -0400, Josef Bacik wrote:
> On Mon, Oct 07, 2019 at 04:17:41PM -0400, Dennis Zhou wrote:
> > 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@kernel.org>
> > ---
> >  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));
> 
> Small nit, instead
> 
> 			delay = nsecs_to_jiffies(cache->discard_delay - now);
> 			delay = max_t(u64, delay,
> 				      atomic_read(&discard_ctl->delay);
> 
> Looks a little cleaner.  Otherwise

Hmmm. Does that work if now > cache->discard_delay? I'm just worried
about the max_t with type u64.

> 
> Reviewed-by: Josef Bacik <josef@toxicpanda.com>
> 
> Thanks,
> 
> Josef

Thanks,
Dennis

Patch
diff mbox series

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,
 };