Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!convex!tchrist@convex.COM
From: tchrist@convex.COM (Tom Christiansen)
Newsgroups: comp.lang.perl
Subject: Re: speed: V2 verses V3
Message-ID: <4047@convex.UUCP>
Date: 17 Dec 89 19:13:28 GMT
References: <1808@uvaarpa.virginia.edu> <6609@jpl-devvax.JPL.NASA.GOV>
Sender: usenet@convex.UUCP
Reply-To: tchrist@convex.COM (Tom Christiansen)
Organization: CONVEX Software Development, Richardson, TX
Lines: 96

>I'd be more interested in comparisons of text processing performance.
>You'll probably find that some tasks are a lot faster, some are a little
>faster, and some are a little slower.  Hopefully a net gain.

Here are some timings on text handling.  The program is a quickie to
extract all termcap entries that match the command arguments, inspired by
from Larry's lib/termcap.pl Tgetent() routine.

Here are the relevant data:

    % wc /etc/termcap
	2235    8179  102598 /etc/termcap

    % grep -n 'wyse50[:|]' /etc/termcap
    2060:ye|w50|wyse50|Wyse 50:\

    % cat gent
    $| = 1; $\ = "\n";
    for $arg (@ARGV) { do gentry($arg); } 

    sub gentry {
	local ($entry) = @_;
	$TERMCAP = '/etc/termcap';
	open TERMCAP || die "can't open $TERMCAP: $!\n";
	while (<TERMCAP>) {
	    next if /^#/;
	    next if /^\t/;
	    next unless /^(\S*\|)?${entry}[|:]/;
	    chop;
	    while (chop eq '\\') {
		$_ .= <TERMCAP>;
		chop;
	    } 
	    $_ .= ':';
	    s/:\t*:/:/g;
	    print;
	} 
    }

C1 timings: (32 meg)

    c-120% time perl2 gent wyse50 wyse50 wyse50 > /dev/null
    10.5u 1.9s 0:13 89% 0+0k 33+0io 60pf+0w
    c-120% time perl3 gent wyse50 wyse50 wyse50 > /dev/null
    6.9u 0.6s 0:08 89% 0+8k 0+1io 67pf+0w

C2 timings: (128 meg)

    c-220% time perl2 gent wyse50 wyse50 wyse50 > /dev/null
    2.4u 0.7s 0:03 82% 0+0k 25+0io 46pf+0w
    c-220% time perl3 gent wyse50 wyse50 wyse50 > /dev/null
    1.6u 0.1s 0:01 92% 0+0k 7+0io 51pf+0w

Extended precision C2 timings:

    c-220% /bin/time -e perl2 gent wyse50 wyse50 wyse50 > /dev/null
	 3.884330 real        2.448687 user        0.760707 sys
    c-220% /bin/time -e perl3 gent wyse50 wyse50 wyse50 > /dev/null
	 2.737149 real        1.709143 user        0.164598 sys


That means that for THIS application on THESE architectures and THESE
configurations, perl3 runs in 2/3 the user time that perl2 does on both
architectures, and just 1/3 and 1/5 system time respectively on a c1 and a
c2.  (The difference in system time ratios MAY be because the c1 was running
ConvexOS 7.1 the c2 had version 8.0 instead.)  This is sure a pretty nice
overall performance increase in my book.

Oddly enough, on a diskless sun/350 with 4 meg of memory, there was little
variance in user time (5%) but a 50% speedup in system time between perl2
and perl3.

Another interesting note is that if you combine these these 2 statments:
    next if /^#/;
    next if /^\t/;
into 
    next if /^#/ || /^\t/;
then your user time goes from 1.7 to 2.0 on the c2 for perl3, but if 
you instead make them:
    next if /^[#\t]/;
it doesn't change.   Interesting optimizations going on here somewhere.

What kinds of ratios do people get for other machines?


--tom


DISCLAIMER: These timings should not be construed to be official
benchmarks from my employer, whom I do not represent in this capacity.  
They are presented only to illustrate ratios between perl2 and perl3.


    Tom Christiansen                       {uunet,uiucdcs,sun}!convex!tchrist 
    Convex Computer Corporation                            tchrist@convex.COM
		 "EMACS belongs in <sys/errno.h>: Editor too big!"