tcsh script: can you time parts of the script?

BrianK · 01-28-2010, 09:00 PM

In lots of different languages, you can do a kind of stop watch around a function or group of lines to see how long it/they takes.

Can you do something like that in tcsh? I need to be able to time in at least tenths of a second & preferably hundredths. What I'm trying to do is something like this:

Code:

#!/bin/tcsh -f

`do_some_stuff`

start = date

foreach f in (`foo`)
  do_something
end

end = date

elapsed = end - start

echo "It took $elapsed seconds"

Is something like this possible?

I don't want to "time" the whole script because I want to time several parts of the script to see where the slowness is.

rweaver · 01-29-2010, 03:37 PM

Date can display the current nanoseconds also which would be more useful for timing...

Code:

core:~$ date "+%F %T.%N"
2010-01-29 16:35:20.240816070
core:~$

or (easier to start with seconds & nanoseconds)

Code:

core:~$ date "+%s.%N"
1264801049.611436547
core:~$

BrianK · 01-29-2010, 03:50 PM

Ahh nice. I didn't know date had that much resolution. I wrote a little C program to do it for me, but I like using date better.

Thanks!

tuxdev · 01-29-2010, 05:30 PM

nanosecond resolution for timing is completely worthless. Variation due to scheduling overhead is far less precise, on the order of tenths of seconds. Use the "time" command.

The first mistake, though, is scripting in (t)csh.
http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/

BrianK · 01-29-2010, 06:32 PM

Quote:

Originally Posted by tuxdev

nanosecond resolution for timing is completely worthless. Variation due to scheduling overhead is far less precise, on the order of tenths of seconds. Use the "time" command.

I don't think you can use time from within a script, though, can you? IN other words, can I run time around 3 loops within a script to see how long each loop takes?

rweaver · 02-01-2010, 03:59 PM

You could use time to call separate scripts to time their output, and it also work on loops and individual as well as commands (of course) eg:

Code:

time for i in `ls`; do echo $i; done
time ls -al

makyo · 02-02-2010, 03:49 PM

Hi.

If you are using tcsh:

Code:

       time    If set to a number, then the time builtin (q.v.) executes auto-
               matically after each command which takes more  than  that  many
               CPU seconds. 

-- excerpt from man tcsh

For example, using a local program burn to use an approximate amount of CPU time:

Code:

#!/usr/bin/env tcsh

# @(#) s1	Demonstrate tcsh automatic timing of simple commands.

echo
setenv LC_ALL C ; setenv LANG C
echo "Environment: LC_ALL = $LC_ALL, LANG = $LANG"
echo "(Versions displayed with local utility version)"
sh -c "version >/dev/null 2>&1" && version "=o" tcsh
echo

set time = 1
echo " Time set to $time"
echo " Burning for 2"
burn 2

echo
echo " Time for burn of 3"
burn 3

echo
exit 0

producing:

Code:

% ./s1

Environment: LC_ALL = C, LANG = C
(Versions displayed with local utility version)
OS, ker|rel, machine: Linux, 2.6.26-2-amd64, x86_64
Distribution        : Debian GNU/Linux 5.0 
tcsh 6.14.00

 Time set to 1
 Burning for 2
calibration end = 0.22, start = 0
Iterations = 50000, time = 0.22 seconds.
Iterations = 404545.454545455, time = 1.84 seconds.
2.060u 0.008s 0:02.13 96.7%	0+0k 0+0io 0pf+0w

 Time for burn of 3
calibration end = 0.22, start = 0
Iterations = 50000, time = 0.22 seconds.
Iterations = 631818.181818182, time = 2.88 seconds.
3.104u 0.004s 0:03.82 81.1%	0+0k 0+0io 0pf+0w

See man tcsh for details ... cheers, makyo

BrianK · 02-02-2010, 07:20 PM

Thanks for the additional suggestions. I'm getting back to this today, so I'll give 'em a try.