On 17/06/2020 21:27, Piscium via arch-general wrote:
The reasons Ubuntu switched in 2006 and Debian in 2011 were speed,
less bugs and more security. A simple benchmark I ran with several
shells using konsole (which is one of the fastest terminals according
to my simple benchmarks):
time ls -R /
• dash 8.45
• zsh 8.53 (1 % bigger)
• bash 17.1
• fish 19.55
Times are in seconds, on my desktop that has a spinning drive. The
first time it takes longer as the system caches stuff so the times
above are after running a few times. I read that in some benchmarks
dash is up to 4 times faster than bash.
I cannot understand the benchmark there. If I run `bash -c "time ls -R
/"` or `dash -c "time ls -R /"`, the only difference is the shell I
started, and the way it reads commands and forks to launch time and/or
ls, isn't it? So I also can have the same test using `{bash,dash} -c
"echo Hello World"`[1], isn't it?
I personnaly suspect that the output handling is responsible of that
long execution time. The konsole may be as fast as it can, it may still
be a bottleneck as it has to print the (long) output of `ls -R`. So I
checked with /dev/null as output. I also get rid of /proc (looping
symlinks…) and /bin, /lib, /share… as clear symlinks of other points—but
it should not change the result as we want to compare execution time.
# bash -c '/usr/bin/time ls -R
/{dev,home,run,sys,usr,boot,etc,opt,root,srv,tmp,var}'
# dash -c '/usr/bin/time ls -R
/{dev,home,run,sys,usr,boot,etc,opt,root,srv,tmp,var}'
After some warm-up executions to put objects in cache, both commands
executes in 1.25 seconds on my computer.
[1] OK, precision of measure changes, we have to loop somewhere—but it
is *how* it is measured, not *what* is measured, which is my problem.
--
Henry-Joseph Audéoud
