Re: Very slow transfers to/from micro SD card on a RPi B+

[Thor Lancelot Simon <tls%panix.com@localhost>]

We should be shipping with DIRHASH turned on.

On Tue, Aug 18, 2015 at 04:19:57PM +0000, Michael van Elst wrote:
> stephanwib%googlemail.com@localhost (Stephan) writes:
> 
> >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.
> 
> Each lookup is linear (unless you use DIRHASH), so the total
> time goes with n^2.
> 
> -- 
> -- 
>                                 Michael van Elst
> Internet: mlelstv%serpens.de@localhost
>                                 "A potential Snark may lurk in every tree."

-- 
  Thor Lancelot Simon	                                     tls%panix.com@localhost

  "We cannot usually in social life pursue a single value or a single moral
   aim, untroubled by the need to compromise with others."      - H.L.A. Hart