XPost: alt.os.linux   
   From: p_d_a_s_i_l_v_a_ns@nonetnoaddress.pt   
      
   Às 12:00 de 14/07/22, Paul escreveu:   
   > On 7/13/2022 10:16 PM, 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 .   
   >>   
   >> 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!!   
   >>   
   >> NOTES:   
   >> I have noticed that before, during the cp -al there were outputs to   
   >> the memory cache during which we could "visit" the drive followed by   
   >> periods of flushing where a simple attempt to change to another dir   
   >> took a while (sometimes ~1 min).   
   >>   
   >> 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.   
   >>   
   >> Thanks for any comments.   
   >> Paulo   
   >>   
   >   
   > What happens if you turn off the encryption ?   
   >   
   > I would want to study the component parts of   
   > the stack, to see if they behave decently by   
   > themselves.   
   >   
   > Even if you temporarily had two disk drives,   
   > one set up with the full stack of stuff,   
   > the second drive with the encryption layer   
   > nullified, that may allow you to bench the   
   > two and see how much worse one is than the other.   
   Unfortunately I cannot test this. I needed a spare similar drive which I   
   don't have now.   
      
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