From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932143AbWF0McN (ORCPT ); Tue, 27 Jun 2006 08:32:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932202AbWF0McN (ORCPT ); Tue, 27 Jun 2006 08:32:13 -0400 Received: from [212.33.187.200] ([212.33.187.200]:44039 "EHLO raad.intranet") by vger.kernel.org with ESMTP id S932143AbWF0McM (ORCPT ); Tue, 27 Jun 2006 08:32:12 -0400 From: Al Boldi To: Pavel Machek Subject: Re: Incorrect CPU process accounting using CONFIG_HZ=100 Date: Tue, 27 Jun 2006 15:32:33 +0300 User-Agent: KMail/1.5 Cc: Jan Engelhardt , linux-kernel@vger.kernel.org References: <200606211716.01472.a1426z@gawab.com> <200606222036.39908.a1426z@gawab.com> <20060626160239.GA3257@elf.ucw.cz> In-Reply-To: <20060626160239.GA3257@elf.ucw.cz> MIME-Version: 1.0 Content-Disposition: inline Content-Type: text/plain; charset="windows-1256" Content-Transfer-Encoding: 7bit Message-Id: <200606271532.33368.a1426z@gawab.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Pavel Machek wrote: > On Thu 2006-06-22 20:36:39, Al Boldi wrote: > > Jan Engelhardt wrote: > > > >Setting CONFIG_HZ=100 results in incorrect CPU process accounting. > > > > > > > >This can be seen running top d.1, that shows top, itself, consuming > > > > 0ms CPUtime. > > > > > > > >Will this bug have consequences for sched.c? > > > > > > Works for me, somewhat. > > > TIME+ says 0:00.02 after 70 secs. (Ergo: top is not expensive on this > > > CPU.) > > > > That's what I thought for a long time. But at closer inspection, top > > d.1 slows down other apps by about the same amount of time at 1000Hz and > > 100Hz, only at 1000Hz it is accounted for whereas at 100Hz it is not. > > It is not a bug... it is design decision. If you eat "too little" cpu > time, you'll be accouted 0 msec. That's what happens at 100Hz... Bummer! Meanwhile, can't "too little" cpu time be made relative to CONFIG_HZ? Thanks! -- Al