A sick idea - mmapped file output

[John Clarke]

On Thu, Nov 02, 2000 at 09:40:31PM -0800, Zack Weinberg wrote:

> - Does it compile on your system?

Yes, with both gcc and Sun cc.

[johnc@medusa ~/tmp]$ gcc -v
Reading specs from /usr/local/lib/gcc-lib/sparc-sun-solaris2.6/egcs-2.93.04/specs
gcc version egcs-2.93.04 19990131 (gcc2 ss-980929 experimental)
[johnc@medusa ~/tmp]$ cc -V
cc: WorkShop Compilers 5.0 98/12/15 C 5.0
usage: cc [ options] files.  Use 'cc -flags' for details
[johnc@medusa ~/tmp]$ uname -a
SunOS medusa.vastsystems.com.au 5.6 Generic_105181-13 sun4u sparc SUNW,Ultra-5_10

> - Does it generate three identical files, each 32MB, when run?  They

Yes.

> - What's the timing report say?

Compiled with gcc (-O2):

        usr     sys     wall
stupid  691     42      751
clever  551     62      624
signal  543     50      998

Compiled with Sun cc (-xO5):

        usr     sys     wall
stupid  714     37      780
clever  500     69      581
signal  554     49      994

> You may notice that the program does not munmap the files before
> exiting.  (There are commented-out munmap calls in the code.)  This is
> because munmap is surprisingly expensive, at least on my machine.

Not so on Solaris.  The times were similar with and without munmap.


Cheers,

John
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