Converting from jiffies to ticks

Jesse Smith jessefrgsmith at
Fri Aug 20 13:05:59 UTC 2010

-----Original Message-----
From: Jeremy Chadwick <freebsd at>
To: Jesse Smith <jessefrgsmith at>
Cc: freebsd-ports <freebsd-ports at>
Subject: Re: Converting from jiffies to ticks
Date: Thu, 19 Aug 2010 12:26:45 -0700

On Thu, Aug 19, 2010 at 04:15:39PM -0300, Jesse Smith wrote:
> I am currently trying to port a program from Linux to FreeBSD which
> detects how much processor time a process is using. The native Linux
> code does this (in part) by reading the number of "jiffies" a given
> process uses. This info is pulled from the /proc/PID/stat file.
> One function is failing on FreeBSD and it's obviously because FreeBSD
> does not have all the same files/data in the /proc directory.
> I've looked around and, as I understand it, FreeBSD uses "ticks" instead
> of "jiffies" to measure process usage. However, how to gather that data
> is a bit lost on me.
> This raises two questions for me:
> 1. Where can I find the equivalent information on FreeBSD? I assume
> there's a function call. Maybe in the kvm_* family? I need to be able to
> get the number of ticks a given PID is using.
> 2. Any idea on what the conversion rate between ticks and jiffies is?
> Are they the same thing, but with different names? Or is it a kilometres
> and miles issue?
> The rest of the program measures everything in "jiffies", so it would be
> ideal for me to get the ticks used on FreeBSD (based on PID), convert it
> to "jiffies" and pass it back to the main program.

I would recommend you re-ask this question on freebsd-hackers.
freebsd-ports isn't really for this purpose.

Thanks Jeremy, I'll check out the freebsd-hackers list.

Chuck, I read the manual entry for acct(2) and acct(5) and it's close to
what I want. But the acct functions appear to just handle stats on
processes that have terminated. I'm trying to get cpu usagbe while
they're still alive.

Appreciate the pointers,

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