Messages in this thread | | | Subject | Re: finding out the value of HZ from userspace | From | Albert Cahalan <> | Date | 20 Mar 2004 09:54:18 -0500 |
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On Sat, 2004-03-20 at 04:56, Arjan van de Ven wrote: > On Tue, Mar 16, 2004 at 11:14:59AM -0500, Albert Cahalan wrote: > > > there is one. Nothing uses it > > > (sysconf() provides this info) > > > > If you have a recent glibc on a recent kernel, it might. > > You could also get a -1 or a supposed ABI value that > > has nothing to do with the kernel currently running. > > The most reliable way is to first look around on the > > stack in search of ELF notes, and then fall back to > > some horribly gross hacks as needed. > > eh sysconf() is the nice way to get to the ELF notes > instead of having to grovel yourself.
Unless there is some hidden feature that lets me specify the ELF note number directly, no way.
The sysconf(_SC_CLK_TCK) call does not return an error code when used on a 2.2.xx i386 kernel. You get an arbitrary value that fails for ARM, Alpha, and any system with modified HZ.
You can't rely on sysconf(_SC_NPROCESSORS_CONF) or sysconf(_SC_NPROCESSORS_ONLN) either. You'll get back a 0 from the SPARC glibc, which really means 0 processors since -1 is the error code.
Whatever the question, "use sysconf" is most likely not the answer.
The man page ought to mention this.
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