http://qs1969.pair.com?node_id=384954

Darby has asked for the wisdom of the Perl Monks concerning the following question:

I just got the Perl CD Bookshelf version 4,and I am going through the exercises for the "learning Perl Objects, References, and Modules book. Chapter 7 ex 2 has you use Benchmark to compare the Schwartzian transformation versus a straight sort using -s. According to the answer, using the Schwartzian transformation should be faster, but I'm getting the opposite results. The Relevant code is:
```use Benchmark qw(timethese);

timethese( -2, {
Ordinary => q{
my @results = sort { -s \$a <=> -s \$b } glob "/bin/*";
},
Schwartzian => q{
my @sorted =
map \$_->[0],
sort { \$a->[1] <=> \$b->[1] }
map [\$_, -s \$_],
glob "/bin/*";
},
});
My results are:
```  Ordinary:  2 wallclock secs ( 0.61 usr +  1.64 sys =  2.25 CPU) @ 23
+7.78/s (n=535)
Schwartzian:  2 wallclock secs ( 1.52 usr +  0.76 sys =  2.28 CPU) @ 2
+02.19/s (n=461)
If I do a 5000 iterations instead of 2 seconds, I get:
```Benchmark: timing 5000 iterations of Ordinary, Schwartzian...
Ordinary: 21 wallclock secs ( 6.46 usr + 14.78 sys = 21.24 CPU) @ 23
+5.40/s (n=5000)
Schwartzian: 26 wallclock secs (17.15 usr +  8.45 sys = 25.60 CPU) @ 1
+95.31/s (n=5000)
The only reason I can think of is that I have a hyperthreading processor. Would that make the difference?
I'm running SuSE 9.1 with the perl version that came with it.
uname -a yields:
```Linux dell 2.6.5-7.104-smp #1 SMP Wed Jul 28 16:42:13 UTC 2004 i686 i6
+86 i386 GNU/Linux
Perl -V yields:
```
Summary of my perl5 (revision 5.0 version 8 subversion 3) configuratio
+n:
Platform:
uname='linux d209 2.6.4 #1 smp thu mar 11 17:56:49 utc 2004 i686 i
+686 i386 gnulinux '
config_args='-ds -e -Dprefix=/usr -Dvendorprefix=/usr -Dinstallusrbinp
+erl
-Dusethreads -Di_db -Di_dbm -Di_ndbm -Di_gdbm -Duseshrplib=true -Dopti
+mize=-O2 -march=i586
-mcpu=i686 -fmessage-length=0 -Wall -Wall -pipe'
hint=recommended, useposix=true, d_sigaction=define
+plicity=define
useperlio=define d_sfio=undef uselargefiles=define usesocks=undef
use64bitint=undef use64bitall=undef uselongdouble=undef
usemymalloc=n, bincompat5005=undef
Compiler:
+-fno-strict-aliasing -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
optimize='-O2 -march=i586 -mcpu=i686 -fmessage-length=0 -Wall -Wal
+l -pipe',
+ct-aliasing'
ccversion='', gccversion='3.3.3 (SuSE Linux)', gccosandvers=''
intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=1
+2
ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t',
+ lseeksize=8
alignbytes=4, prototype=define
ld='cc', ldflags =''
libpth=/lib /usr/lib /usr/local/lib
libs=-lnsl -ldl -lm -lcrypt -lutil -lpthread -lc
perllibs=-lnsl -ldl -lm -lcrypt -lutil -lpthread -lc
libc=, so=so, useshrplib=true, libperl=libperl.so
gnulibc_version='2.3.3'
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-rdynami
cccdlflags='-fPIC', lddlflags='-shared'

Characteristics of this binary (from libperl):
Compile-time options: MULTIPLICITY USE_ITHREADS USE_LARGE_FILES PERL
+_IMPLICIT_CONTEXT
Built under linux
Compiled at Apr  3 2004 00:52:08
@INC: