On 11/5/21 3:11 AM, Nikolay Borisov wrote:

On 29.10.21 г. 21:39, Stefan Roesch wrote:

quoted

This increases the metadata default allocation size from 1GB to 5GB for
volumes with a size greater than 50GB.

Imo such a change would warrant more data about why it's ok. Clearly
there is some internal facebook workload which benefits from this,
however this doesn't automatically mean it will be beneficial for the
wider user base. Also your cover letter doesn't contain any more
specifics about the particular workload. Isn't 5g a bit too steep,
perhaps 2 is larger and yet more conservative?

I understand that this change is getting some questions and a more conservative
value might need to be chosen. Let's wait until all the reviews are in and
then settle on a compromise. 
 

quoted

Signed-off-by: Stefan Roesch <redacted>
---
 fs/btrfs/space-info.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
index 7370c152ce8a..44507262c515 100644
--- a/fs/btrfs/space-info.c
+++ b/fs/btrfs/space-info.c

@@ -195,7 +195,7 @@ static u64 compute_chunk_size_regular(struct btrfs_fs_info *info, u64 flags)
 
 	/* Handle BTRFS_BLOCK_GROUP_METADATA */
 	if (info->fs_devices->total_rw_bytes > 50ULL * SZ_1G)
-		return SZ_1G;
+		return 5ULL * SZ_1G;
 
 	return SZ_256M;
 }