script for determining space consumed by increments

Ben Escoto bescoto@stanford.edu
Mon, 13 May 2002 18:03:13 -0700


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>>>>> "DG" == dean gaudet <dean-list-rdiff-backup@arctic.org>
>>>>> wrote the following on Mon, 13 May 2002 10:22:19 -0700 (PDT)

  DG> i noticed a fair amount of superfluous syscalls in strace output
  DG> on the mirror side:
    ...

Yep, rdiff-backup is almost totally unoptimized, so a lot could be
done...

  DG> my system aren't running at full cpu, or full disk bandwidth
  DG> (dunno about disk seeking), or full net ... which is why i
  DG> suspect serialisation.

So maybe it would be worth it to try conn_bufsize = 32768 or
whatever.  Who knows, you might get 11hrs -> 6hrs.

  DG> there's an async i/o interface named aio, but it's meant to give
  DG> you async i/o on long-term opened files.  on programs which do a
  DG> lot of fs metadata manipulation, the only option for parallelism
  DG> is multithreading or multiprocesses.

Yes, for instance rsync is multiprocess (even when run locally it
makes three processes).  But this leads to a lot of complexity.  I
think rsync was having protocol problems leading to sessions hanging
just a few months ago.  So I don't expect to try multithreading
anytime soon...


--
Ben Escoto

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