Messages in this thread | | | Date | Wed, 6 Aug 2008 15:16:37 -0700 | From | "Ray Lee" <> | Subject | Re: HZ from userspace |
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On Wed, Aug 6, 2008 at 3:07 PM, Piotr Jaroszyński <p.jaroszynski@gmail.com> wrote: >>> I want to be able to convert starttime from /proc/#/stat to absolute >>> time and it seems that I need HZ to do that as it is measured in >>> jiffies. How can I get HZ? I have seen some discussion about this but >>> haven't found a definite answer. procps is using some hacks do it and >>> I would prefer to avoid them. >>> I only need a solution for modern kernels, say 2.6.20+ if that matters. >> >> `man sysconf`, in particular you want sysconf(_SC_CLK_TCK). > > manpage says it's obsolete and i read in some discussion that it only > returns the default and not the real HZ used.
I believe the claim that it's out of date is out of date. manpages 3.0.1 has an update to this, according to a message I saw on this list a month or so ago.
Regardless, the fields you're reading should all be showing USER_HZ which is fixed at 100 per second regardless of the underlying kernel HZ parameter.
Try it.
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