Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!snorkelwacker.mit.edu!paperboy!meissner From: meissner@osf.org (Michael Meissner) Newsgroups: comp.benchmarks Subject: Re: Which benchmarks are useless? Message-ID: Date: 3 May 91 17:53:44 GMT References: <2502@spim.mips.COM> <21720006@hpfcso.FC.HP.COM> <02.May.91.132611.54@cogsci.cog.jhu.edu> Sender: news@OSF.ORG Organization: Open Software Foundation Lines: 19 In-reply-to: wjb@cogsci.cog.jhu.edu's message of 2 May 91 17:26:11 GMT In article <02.May.91.132611.54@cogsci.cog.jhu.edu> wjb@cogsci.cog.jhu.edu writes: | I've heard this "rumor" as well. I always wondered why people | didn't try to test it out by comparing getpid() and getppid() times. Your | PID may not ever change, but your PPID will change to 1 if your parent exits. | This would appear to require that getppid() enter the kernel. Actually, the | real way to speed up both of these system calls is to map a page of memory | read-only into the data space of the process and have the program read this | data directly from where the kernel stores it. I guess this is another | example of the dangers of micro benchmarks and making assumptions about how | different system functions are implemented. But of course if you fork (), your pid also changes...... -- Michael Meissner email: meissner@osf.org phone: 617-621-8861 Open Software Foundation, 11 Cambridge Center, Cambridge, MA, 02142 Considering the flames and intolerance, shouldn't USENET be spelled ABUSENET?