"...User code time... + system code time... = real time..."

Yes:

From the docs:

"The time utility executes and times the specified utility. After the utility finishes, time writes to the standard error stream, (in seconds): the total time elapsed, the time used to execute the utility process and the time consumed by system overhead."

Some observations:

karls-mac-mini:monks karl$ ls -hl very_huge10GB.file 
-rw-r--r--  1 karl  karl    10G 25 Mai 00:53 very_huge10GB.file

karls-mac-mini:monks karl$ time grep karl very_huge10GB.file
nose cuke karl
nose cuke karl
nose cuke karl
nose cuke karl
nose cuke karl

real    2m42.126s
user    0m20.437s
sys    0m5.645s
[download]

karls-mac-mini:monks karl$ ./mce_loop.pl 
nose cuke karl
nose cuke karl
nose cuke karl
nose cuke karl
nose cuke karl
Took 150.555 seconds
[download]

#!/usr/bin/env perl

use Time::HiRes qw( time );
use feature qw(say);

my $start = time;

say qx (grep karl very_huge10GB.file);

printf "Took %.3f seconds\n", time - $start;

__END__

karls-mac-mini:monks karl$ ./wrap.pl 
nose cuke karl
nose cuke karl
nose cuke karl
nose cuke karl
nose cuke karl

Took 157.265 seconds
[download]

For the grep example 60+60+42=162 which is 2m42s. But user+sys (20+5) is 0m25s. What do i miss?

Perhaps it's too late tonight. Or too early in the morning?

Best regards, Karl