Date: Sat, 12 Feb 2005 14:16:51 -0600 From: Dan Nelson <dnelson@allantgroup.com> To: Nimnod <nimnod@gnu.univ.gda.pl> Cc: freebsd-hackers@freebsd.org Subject: Re: how to calculate CPU utilization? Message-ID: <20050212201651.GE49626@dan.emsphone.com> In-Reply-To: <opsl23o6hf5x937e@localhost.kolonianet.pl> References: <opsl23o6hf5x937e@localhost.kolonianet.pl>
next in thread | previous in thread | raw e-mail | index | archive | help
In the last episode (Feb 12), Nimnod said: > i am looking for how to accurately calculate the CPU utilization per > process. i have looked through the top sources, and found out it's > using the kvm lib, which isn't suitable for my purpose. Why not? You don't need to be setuid root to call kvm functions; when possible they fetch their info via sysctl. Neither top nor ps are setuid. > is there a way to accurately calculate %CPU based on information from > the struct proc ? it does carry info on proc time (p_runtime), > system, user and interrupt ticks, and previous system, user and int > times in usec, but i just can't make the right equation to get the > appropriate values. first, i attempted to divide the process runtime > by system uptime, which seemed ok, but obviously this is not the way. > could anyone please help? You need to take two samples separated by some delay (1 or 5 seconds maybe), then take their difference and divide by the delay. That will give you the cpu usage over that period. -- Dan Nelson dnelson@allantgroup.com
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20050212201651.GE49626>