Date: Sun, 21 Jan 2001 15:22:46 -0800 From: "Crist J. Clark" <cjclark@reflexnet.net> To: Cliff Sarginson <cliff@raggedclown.net> Cc: Mike Meyer <mwm@mired.org>, Gustavo Vieira Goncalves Coelho Rios <gustavo@ifour.com.br>, questions@FreeBSD.ORG Subject: Re: small program eats lot of memory Message-ID: <20010121152246.X10761@rfx-216-196-73-168.users.reflex> In-Reply-To: <01012121054701.03293@buffy>; from cliff@raggedclown.net on Sun, Jan 21, 2001 at 09:05:47PM %2B0100 References: <14955.1209.195848.394006@guru.mired.org> <01012121054701.03293@buffy>
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On Sun, Jan 21, 2001 at 09:05:47PM +0100, Cliff Sarginson wrote:
> On Sunday 21 January 2001 16:48, Mike Meyer wrote:
> > Gustavo Vieira Goncalves Coelho Rios <gustavo@ifour.com.br> types:
> > > I compiled and executed a small program and it's eating about 336
> > > of real memory (rss) and 840 of virtual size memory (vsz), may some
> > > one explain why a simple program eats about 1 MB of memory?
> >
> > You linked it shared, right? That 1MB includes all of every shared
> > library it uses, whether it uses those functions or not.
>
> Pardon ! It certainly does not ! That is the point of shared libraries -
> the code is *shared* between processes using it. The required code is
> then made dynamically available.
The purpose of shared libraries is to share _disk_ space, not memory
space.
It's an easy enough test. Take the original little program,
$ cat > sizetest.c <<EOF
#include <stdio.h>
#include <stdlib.h>
int main() {
sleep(300);
return 0;
}
EOF
$ cc -o sizetest sizetest.c
$ cc -static -o sizetest_s sizetest.c
$ ls -l sizetest{,_s}
-rwxr-xr-x 1 cjc wheel 4380 Jan 21 15:17 sizetest
-rwxr-xr-x 1 cjc wheel 6947 Jan 21 15:17 sizetest_s
$ ./sizetest & ./sizetest_s & sleep 10 ; ps aux | grep sizetest
cjc 31567 0.0 0.2 840 272 p2 S 3:17PM 0:00.00 ./sizetest
cjc 31568 0.0 0.0 136 20 p2 S 3:17PM 0:00.00 ./sizetest_s
The static one takes up less memory according to ps(1), but more
disk.
--
Crist J. Clark cjclark@alum.mit.edu
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