In message <1279395948-25864-1-git-send-email...@denx.de> I wrote:
>
> The following patch series adds some utilities (qsort and hash table
> based database functions) and uses these to reimplement the code used
> for the internal handling of environment variables.
>
>
> Motivation:
>
> * Old environment code used a pessimizing implementation:
> - variable lookup used linear search => slow
> - changed/added variables were added at the end, i. e. most
> frequently used variables had the slowest access times => slow
> - each setenv() would calculate the CRC32 checksum over the whole
> environment block => slow
Just to give a datapoint for speed:
measured on TQM5200 (MPC5200 at 400 MHz, environment size 16 kB):
OLD implementation:
=> sete ttt 'date;for i in 0 1 2 3 4 5 6 7 8 9 ; do for j in 0 1 2 3 4
5 6 7 8 9 ; do for k in 0 1 2 3 4 5 6 7 8 9 ; do run tt ; done ; done ;
done;date'
=> sete tt 'sete var1 xxx;sete var2 ${var1};sete var1 ${var2};sete
var1;sete var2'
=> run tt
=> run ttt
Date: 1910-07-17 (unknown day) Time: 22:02:31
Date: 1910-07-17 (unknown day) Time: 22:03:27
New implementation:
=> run ttt
Date: 1910-07-17 (unknown day) Time: 20:45:51
Date: 1910-07-17 (unknown day) Time: 20:45:53
I. e. we have 56 versus 2 seconds.
I haven't run intensive tests, but in general I think we can see that
scripts referncing environment variables will typically run faster by
a factor of 10, or more.
Best regards,
Wolfgang Denk
--
DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: w...@denx.de
Time is an illusion perpetrated by the manufacturers of space.
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