Re: [9fans] impact of dynamic libraries on the speed of fork()

[Micah Stetson <micah@cnm-vra.com>]

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> I wrote a really simple program, forktest.c.

Chris beat me to the punch, but I'm posting anyway because I went a
different direction.  I wrote some rc scripts that make static and
dynamic libraries of various sizes and programs that use those
libraries (trivially).  For each number of functions 1, 10, 100, 1000,
10000, 100000 I timed static and dynamic execution of a program that
conditionally calls that many functions in 1 or 10 libraries.  The
scripts are attached, run mklibs, then mkprogs, then runtests.  Below
are the results of a single run on my laptop (fixed with font looks
better).  I can't spend any more time on this, but it was a fun
morning goof-off.

Static (functions libraries binary-size user system elapsed)
     1  1  556898 0.24 0.50 0.78
    10  1  557324 0.28 0.44 0.82
    10 10  557913 0.32 0.42 0.81
   100  1  561737 0.24 0.50 0.84
   100 10  562196 0.28 0.46 0.79
  1000  1  609496 0.29 0.47 0.83
  1000 10  606381 0.26 0.48 0.84
 10000  1 1105475 0.30 0.44 0.87
 10000 10 1083834 0.28 0.47 0.82
100000  1 6245494 0.27 0.48 0.88
100000 10 6043871 0.28 0.48 0.81

Dynamic (functions libraries binary-size user system elapsed)
     1  1     6489 0.49 0.86 1.39
    10  1     7322 0.52 0.86 1.45
    10 10     7464 0.83 1.14 2.03
   100  1    16366 0.59 0.78 1.42
   100 10    16177 1.14 1.11 2.35
  1000  1   108268 0.55 0.87 1.47
  1000 10   104496 0.88 1.12 2.07
 10000  1  1077758 0.81 0.98 1.89
 10000 10  1037387 1.12 1.36 2.63
100000  1 10915272 2.79 2.50 6.31
100000 10 10517862 3.13 3.68 7.13

I think dynamic 100-10 is a fluke, I also think it's interesting that
the dynamic binaries are bigger above 10000 function calls.  Don't
know why, don't have time to figure it out.

Micah

[-- Attachment #2: mklibs --]
[-- Type: application/octet-stream, Size: 384 bytes --]

#!/usr/local/plan9/bin/rc

letters=(a b c d e f g h i j)
sizes=(1 10 100 1000 10000 100000)

for(l in $letters){
	for(n in $sizes){
		seq $n | sed 's/.*/int '^$l$n^'_&(int);/' >tests/lib$l$n^.h
		seq $n | sed 's/.*/int '^$l$n^'_&(int i) { return i+&; }/' > tests/lib$l$n^.c
		gcc -c -o lib$l$n^.o lib$l$n^.c
		ar rcs lib$l$n^.a lib$l$n^.o
		ld -shared -o lib$l$n^.so lib$l$n^.o
	}
}


[-- Attachment #3: mkprog --]
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#!/usr/local/plan9/bin/rc

for(lib)
	echo '#include "lib'^$lib^'.h"'

cat <<EOF

int
main(int argc, char* argv)
{
	int i = 0;
	if(argc == 1)
		return 0;
EOF

for(lib){
	n = `{echo $lib | 9 sed 's/[a-z]+([0-9]+)/\1/'}
	seq $n | sed 's/.*/	i += '^$lib^'_&(i);/'
}

cat <<EOF

	return i;
}
EOF

[-- Attachment #4: mkprogs --]
[-- Type: application/octet-stream, Size: 646 bytes --]

#!/usr/local/plan9/bin/rc

fn build {
	name=$1; shift
	./mkprog $* > test$name^.c
	gcc -c -o test$name^.o test$name^.c
	gcc -static -o test$name^-s test$name^.o -L. -l^$*
	gcc -o test$name^-d test$name^.o -L. -l^$*
}

build 1-1 a1
build 10-1 a10
build 10-10 a1 b1 c1 d1 e1 f1 g1 h1 i1 j1
build 100-1 a100
build 100-10 a10 b10 c10 d10 e10 f10 g10 h10 i10 j10
build 1000-1 a1000
build 1000-10 a100 b100 c100 d100 e100 f100 g100 h100 i100 j100
build 10000-1 a10000
build 10000-10 a1000 b1000 c1000 d1000 e1000 f1000 g1000 h1000 i1000 j1000
build 100000-1 a100000
build 100000-10 a10000 b10000 c10000 d10000 e10000 f10000 g10000 h10000 i10000 j10000

[-- Attachment #5: runtests --]
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#!/usr/local/plan9/bin/rc

LD_LIBRARY_PATH=`{pwd}

fn t {
	echo Testing $1^-s...
	time rc -c 'seq 1000 | sed ''s/.*/.\/'^$1^'-s/'' | rc'
	echo Testing $1^-d...
	time rc -c 'seq 1000 | sed ''s/.*/.\/'^$1^'-d/'' | rc'
}

t test1-1
t test10-1
t test10-10
t test100-1
t test100-10
t test1000-1
t test1000-10
t test10000-1
t test10000-10
t test100000-1
t test100000-10