From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261159AbTJQWsx (ORCPT ); Fri, 17 Oct 2003 18:48:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261168AbTJQWsx (ORCPT ); Fri, 17 Oct 2003 18:48:53 -0400 Received: from dyn-ctb-210-9-245-184.webone.com.au ([210.9.245.184]:20484 "EHLO chimp.local.net") by vger.kernel.org with ESMTP id S261159AbTJQWsv (ORCPT ); Fri, 17 Oct 2003 18:48:51 -0400 Message-ID: <3F9071C3.5070909@cyberone.com.au> Date: Sat, 18 Oct 2003 08:48:35 +1000 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.4) Gecko/20030827 Debian/1.4-3 X-Accept-Language: en MIME-Version: 1.0 To: Albert Cahalan CC: linux-kernel mailing list Subject: Re: decaying average for %CPU References: <1066358155.15931.145.camel@cube> <3F8F5A53.50209@cyberone.com.au> <1066359629.15920.161.camel@cube> <3F8F6020.2040206@cyberone.com.au> <1066364241.15931.180.camel@cube> In-Reply-To: <1066364241.15931.180.camel@cube> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Albert Cahalan wrote: >On Thu, 2003-10-16 at 23:21, Nick Piggin wrote: > > >>Albert Cahalan wrote: >> >> >>>On Thu, 2003-10-16 at 22:56, Nick Piggin wrote: >>> >>> >>>>Albert Cahalan wrote: >>>> >>>> >>>> >>>>>The UNIX standard requires that Linux provide >>>>>some measure of a process's "recent" CPU usage. >>>>>Right now, it isn't provided. You might run a >>>>>CPU hog for a year, stop it ("kill -STOP 42") >>>>>for a few hours, and see that "ps" is still >>>>>reporting 99.9% CPU usage. This is because the >>>>>kernel does not provide a decaying average. >>>>> >>>>> >>>>> >>>>I think the kernel provides enough info for userspace to do >>>>the job, doesn't it? >>>> >>>> >>>> >>>I'm pretty sure not. Linux provides: >>> >>>per-process start time >>>current time >>>per-process total (lifetime) CPU usage >>>units of time measurement (awkwardly) >>>boot time >>> >>> >>But your userspace program can calculate deltas in the total >>CPU statistics. Yep, its in /proc/stat. >> >> > >Huh? > >This isn't about "top", which displays % of CPU >time used over the refresh interval by reading >all the process data multiple times. > >This is about programs like "ps", which read >everything and then spit out the output. > >I hope you're not suggesting to read things >twice with a huge sleep(5) in the middle, or >to run some kind of daemon that polls /proc >once a second. That's far beyond horrid. > > Yeah I spose it is.