XPost: alt.os.linux   
   From: user@example.net   
      
   On 14/07/2022 04.16, Paulo da Silva wrote:   
   > Hi!   
   >   
   > I have a USB external backup volume with btrfs.   
   > The backup script is a simple cp -al   followed by a rsync   
   > to update .   
      
   I prefer to use snapshots and then send/receive, this tend to take a lot   
   shorter time than cp or rsync as you will only send the changes and   
   nothing more.   
      
      
   > The cp -al took 10-20 mins. in kernel 5.13 and before that.   
   > Now, with 5.15, without any changes, it is taking a few hours!!   
      
   I don't remember which kernel 5 version had a change in local cache,   
   which could in some cases cause things to work differently.   
      
   Have you tested with other file system on a similar usb device? This to   
   figure out if it's related to btrfs or usb.   
      
   There are speed optimization in 5.16 regarding btrfs, so an upgrade   
   could be good.   
      
      
   > Now, I can always navigate inside the drive without any delay when cp   
   > -al is in course! It seems like there is no memory cache although the   
   > memory cache still grows and shrinks.   
   >   
   > BTW, my mount command is   
   > mount /dev/mapper/TEMP /mnt1 -onoatime,compress-force=zstd > There is an   
   encryption layer below the fs.   
      
   Could be this that causing the problem and not btrfs itself.   
      
   I would recommend you check up changes in the crypto layer too.   
      
   Also it could be a combination of crypto + btrfs, but should in such   
   case been resolved in later kernel versions.   
      
   --   
      
     //Aho   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)