write performance difference 3.18.21/git f2fs

[Marc Lehmann <schmorp@schmorp.de>]

Ok, before I tried the f2fs git I made another short test with the
original 3.18.21 f2fs, and it was as fast as before. Then I used the
faulty f2fs module,. which forced a reboot.

Now I started to redo the 3.18.21 test + git f2fs, with the same parameters
(specifically, -s90), and while it didn't start out to be as slow as 4.2.1,
it's similarly slow.

After 218GiB, I stopped the test, giving me an average of 50MiB/s.

Here is typical dstat output (again, dsk/sde):

http://ue.tst.eu/7a40644b3432e2932bdd8c1f6b6fc32d.txt

So less read behaviour than with 4.2.1, but also very slow writes.

That means the performance drop moves with f2fs, not the kernel version.

This is the resulting status:

http://ue.tst.eu/6d94e9bfad48a433bbc6f7daeaf5eb38.txt

Just for fun I'll start doing a -s64 run.

-- 
                The choice of a       Deliantra, the free code+content MORPG
      -----==-     _GNU_              http://www.deliantra.net
      ----==-- _       generation
      ---==---(_)__  __ ____  __      Marc Lehmann
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      -=====/_/_//_/\_,_/ /_/\_\

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