On Tue, Oct 25, 2011 at 01:56:48PM +0200, Christian Brunner wrote:
> 2011/10/24 Josef Bacik <josef@xxxxxxxxxx>:
> > On Mon, Oct 24, 2011 at 10:06:49AM -0700, Sage Weil wrote:
> >> [adding linux-btrfs to cc]
> >>
> >> Josef, Chris, any ideas on the below issues?
> >>
> >> On Mon, 24 Oct 2011, Christian Brunner wrote:
> >> >
> >> > - When I run ceph with btrfs snaps disabled, the situation is getting
> >> > slightly better. I can run an OSD for about 3 days without problems,
> >> > but then again the load increases. This time, I can see that the
> >> > ceph-osd (blkdev_issue_flush) and btrfs-endio-wri are doing more work
> >> > than usual.
> >>
> >> FYI in this scenario you're exposed to the same journal replay issues that
> >> ext4 and XFS are. The btrfs workload that ceph is generating will also
> >> not be all that special, though, so this problem shouldn't be unique to
> >> ceph.
> >>
> >
> > Can you get sysrq+w when this happens? I'd like to see what btrfs-endio-write
> > is up to.
>
> Capturing this seems to be not easy. I have a few traces (see
> attachment), but with sysrq+w I do not get a stacktrace of
> btrfs-endio-write. What I have is a "latencytop -c" output which is
> interesting:
>
> In our Ceph-OSD server we have 4 disks with 4 btrfs filesystems. Ceph
> tries to balance the load over all OSDs, so all filesystems should get
> an nearly equal load. At the moment one filesystem seems to have a
> problem. When running with iostat I see the following
>
> Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s
> avgrq-sz avgqu-sz await svctm %util
> sdd 0.00 0.00 0.00 4.33 0.00 53.33
> 12.31 0.08 19.38 12.23 5.30
> sdc 0.00 1.00 0.00 228.33 0.00 1957.33
> 8.57 74.33 380.76 2.74 62.57
> sdb 0.00 0.00 0.00 1.33 0.00 16.00
> 12.00 0.03 25.00 19.75 2.63
> sda 0.00 0.00 0.00 0.67 0.00 8.00
> 12.00 0.01 19.50 12.50 0.83
>
> The PID of the ceph-osd taht is running on sdc is 2053 and when I look
> with top I see this process and a btrfs-endio-writer (PID 5447):
>
> PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
> 2053 root 20 0 537m 146m 2364 S 33.2 0.6 43:31.24 ceph-osd
> 5447 root 20 0 0 0 0 S 22.6 0.0 19:32.18 btrfs-endio-wri
>
> In the latencytop output you can see that those processes have a much
> higher latency, than the other ceph-osd and btrfs-endio-writers.
>
> Regards,
> Christian
Ok just a shot in the dark, but could you give this a whirl and see if it helps
you? Thanks
Josef
diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c
index 125cf76..fbc196e 100644
--- a/fs/btrfs/delayed-ref.c
+++ b/fs/btrfs/delayed-ref.c
@@ -210,9 +210,9 @@ int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
}
int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans,
- struct list_head *cluster, u64 start)
+ struct list_head *cluster, u64 start, unsigned long max_count)
{
- int count = 0;
+ unsigned long count = 0;
struct btrfs_delayed_ref_root *delayed_refs;
struct rb_node *node;
struct btrfs_delayed_ref_node *ref;
@@ -242,7 +242,7 @@ int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans,
node = rb_first(&delayed_refs->root);
}
again:
- while (node && count < 32) {
+ while (node && count < max_count) {
ref = rb_entry(node, struct btrfs_delayed_ref_node, rb_node);
if (btrfs_delayed_ref_is_head(ref)) {
head = btrfs_delayed_node_to_head(ref);
diff --git a/fs/btrfs/delayed-ref.h b/fs/btrfs/delayed-ref.h
index e287e3b..b15a6ad 100644
--- a/fs/btrfs/delayed-ref.h
+++ b/fs/btrfs/delayed-ref.h
@@ -169,7 +169,8 @@ btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr);
int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
struct btrfs_delayed_ref_head *head);
int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans,
- struct list_head *cluster, u64 search_start);
+ struct list_head *cluster, u64 search_start,
+ unsigned long max_count);
/*
* a node might live in a head or a regular ref, this lets you
* test for the proper type to use.
diff --git a/fs/btrfs/dir-item.c b/fs/btrfs/dir-item.c
index 31d84e7..c190282 100644
--- a/fs/btrfs/dir-item.c
+++ b/fs/btrfs/dir-item.c
@@ -81,6 +81,7 @@ int btrfs_insert_xattr_item(struct btrfs_trans_handle *trans,
u32 data_size;
BUG_ON(name_len + data_len > BTRFS_MAX_XATTR_SIZE(root));
+ WARN_ON(trans->endio);
key.objectid = objectid;
btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 4eb7d2b..0977a10 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2295,7 +2295,7 @@ again:
* lock
*/
ret = btrfs_find_ref_cluster(trans, &cluster,
- delayed_refs->run_delayed_start);
+ delayed_refs->run_delayed_start, count);
if (ret)
break;
@@ -2338,7 +2338,8 @@ again:
node = rb_next(node);
}
spin_unlock(&delayed_refs->lock);
- schedule_timeout(1);
+ if (need_resched())
+ schedule_timeout(1);
goto again;
}
out:
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index f12747c..73a5e66 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1752,6 +1752,7 @@ static int btrfs_finish_ordered_io(struct inode *inode, u64 start, u64 end)
else
trans = btrfs_join_transaction(root);
BUG_ON(IS_ERR(trans));
+ trans->endio = 1;
trans->block_rsv = &root->fs_info->delalloc_block_rsv;
if (test_bit(BTRFS_ORDERED_COMPRESSED, &ordered_extent->flags))
@@ -2057,8 +2058,11 @@ void btrfs_run_delayed_iputs(struct btrfs_root *root)
LIST_HEAD(list);
struct btrfs_fs_info *fs_info = root->fs_info;
struct delayed_iput *delayed;
+ struct btrfs_trans_handle *trans;
int empty;
+ trans = current->journal_info;
+ WARN_ON(trans && trans->endio);
spin_lock(&fs_info->delayed_iput_lock);
empty = list_empty(&fs_info->delayed_iputs);
spin_unlock(&fs_info->delayed_iput_lock);
diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
index a1c9404..ab68cfa 100644
--- a/fs/btrfs/ordered-data.c
+++ b/fs/btrfs/ordered-data.c
@@ -527,12 +527,15 @@ int btrfs_wait_ordered_extents(struct btrfs_root *root,
*/
int btrfs_run_ordered_operations(struct btrfs_root *root, int wait)
{
+ struct btrfs_trans_handle *trans;
struct btrfs_inode *btrfs_inode;
struct inode *inode;
struct list_head splice;
+ trans = (struct btrfs_trans_handle *)current->journal_info;
INIT_LIST_HEAD(&splice);
+ WARN_ON(trans && trans->endio);
mutex_lock(&root->fs_info->ordered_operations_mutex);
spin_lock(&root->fs_info->ordered_extent_lock);
again:
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 29bef63..009d2db 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -310,6 +310,7 @@ again:
h->use_count = 1;
h->block_rsv = NULL;
h->orig_rsv = NULL;
+ h->endio = 0;
smp_mb();
if (cur_trans->blocked && may_wait_transaction(root, type)) {
@@ -467,20 +468,17 @@ static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
while (count < 4) {
unsigned long cur = trans->delayed_ref_updates;
trans->delayed_ref_updates = 0;
- if (cur &&
- trans->transaction->delayed_refs.num_heads_ready > 64) {
- trans->delayed_ref_updates = 0;
-
- /*
- * do a full flush if the transaction is trying
- * to close
- */
- if (trans->transaction->delayed_refs.flushing)
- cur = 0;
- btrfs_run_delayed_refs(trans, root, cur);
- } else {
+ if (!cur ||
+ trans->transaction->delayed_refs.num_heads_ready <= 64)
break;
- }
+
+ /*
+ * do a full flush if the transaction is trying
+ * to close
+ */
+ if (trans->transaction->delayed_refs.flushing && throttle)
+ cur = 0;
+ btrfs_run_delayed_refs(trans, root, cur);
count++;
}
@@ -498,6 +496,7 @@ static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
* our use_count.
*/
trans->use_count++;
+ WARN_ON(trans->endio);
return btrfs_commit_transaction(trans, root);
} else {
wake_up_process(info->transaction_kthread);
diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h
index 02564e6..7eae404 100644
--- a/fs/btrfs/transaction.h
+++ b/fs/btrfs/transaction.h
@@ -55,6 +55,7 @@ struct btrfs_trans_handle {
struct btrfs_transaction *transaction;
struct btrfs_block_rsv *block_rsv;
struct btrfs_block_rsv *orig_rsv;
+ unsigned endio;
};
struct btrfs_pending_snapshot {
--
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