2015-08-17 21:30 GMT+02:00 Michael van Elst <mlel...@serpens.de>:
> stephan...@googlemail.com (Stephan) writes:
>
> >I have just rebooted with WAPBL enabled. Some quick notes:
>
> >-Sequential write speed is a little lower, around 5,4 MB/s.
>
>
> WAPBL is rather slow on SD cards because SD cards are very slow
> when writing small chunks. So even when WAPBL excels, like unpacking
> lots of files or removing a directory tree, it is slow because the
> sequential journal is written in small blocks.
>
That might be all right. However, creating many files becomes worse the
more files are being created. That is on all kinds of devices I´ve seen.
This is from an amd64 server box with an aac raid controller.
/root/test/files> time seq 1 10000|xargs touch
3.10s real 0.01s user 3.07s system
/root/test/files> rm *
/root/test/files> time seq 1 20000|xargs touch
9.88s real 0.01s user 8.51s system
/root/test/files> rm *
/root/test/files> time seq 1 30000|xargs touch
23.45s real 0.04s user 20.41s system
/root/test/files> time seq 1 40000|xargs touch
43.35s real 0.05s user 38.32s system
That is clearly not linear.
>
> --
> --
> Michael van Elst
> Internet: mlel...@serpens.de
> "A potential Snark may lurk in every tree."
>
