Date: Fri, 2 Apr 2004 23:51:18 +0200 (CEST) From: Jose Marcio Martins da Cruz <martins@saci.ensmp.fr> To: dnelson@allantgroup.com (Dan Nelson) Cc: freebsd-hackers@freebsd.org Subject: Re: Pointers about CPU load measuring Message-ID: <200404022151.i32LpIw5009567@saci.ensmp.fr> In-Reply-To: <20040402214012.GA49311@dan.emsphone.com> from "Dan Nelson" at Apr 02, 2004 03:40:12 PM
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> > In the last episode (Apr 02), Mark said: > > Dan Nelson wrote: > > >>> Someone can send some pointers on how to measure global CPU load > > >>> under FreeBSD from a C program ? I'm looking for values for > > >>> idle/kernel/user, in a similar way as does top. Is there any > > >>> pointer or doc ?. I'd like to avoir browsing top code. > > >> > > >> Use sysctlbyname(3) to retrieve vm.loadavg, which is a struct > > >> loadavg (defined in <sys/resource.h>) > > > > > > Actually the kern.cp_time variable might be better if you want > > > idle/kernel/user values. > > > > I current let snmpd do the job. Is that as accurate as manually > > reading the kern.cp_time variable? > > If you're talking about enterprises.ucdavis.systemStats, then yes. > Snmpd digs directly into /dev/kmem instead of using sysctl (so it can > run on older kernels that didn't provide the sysctl variable), but the > values are the same. enterprises.ucdavis.laTable is populated from the > vm.loadavg sysctl variable. If I'm not wrong, loadavg gives the mean number of processes in the run queue averaged on 1, 5 and 15 minutes. This gives an idea of system load but lacks precision. It seems to me that kern.cp_time counters is a better metrics of CPU load. > > -- > Dan Nelson > dnelson@allantgroup.com >
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