Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 16 Apr 2002 05:31:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 16 Apr 2002 05:31:38 -0400 Received: from [195.173.53.244] ([195.173.53.244]:25352 "HELO BELLE") by vger.kernel.org with SMTP id ; Tue, 16 Apr 2002 05:31:37 -0400 Subject: RE: Why HZ on i386 is 100 ? From: Liam Girdwood To: BALBIR SINGH Cc: William Lee Irwin III , Olaf Fraczyk , linux-kernel@vger.kernel.org In-Reply-To: Content-Type: text/plain Content-Transfer-Encoding: 7bit X-Mailer: Ximian Evolution 1.0.3 Date: 16 Apr 2002 11:29:07 +0100 Message-Id: <1018952961.31914.446.camel@swordfish> Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2002-04-16 at 09:18, BALBIR SINGH wrote: > I remember seeing somewhere unix system VII used to have HZ set to 60 > for the machines built in the 70's. I wonder if todays pentium iiis and ivs > should still use HZ of 100, though their internal clock is in GHz. > > I think somethings in the kernel may be tuned for the value of HZ, these > things would be arch specific. > > Increasing the HZ on your system should change the scheduling behaviour, > it could lead to more aggresive scheduling and could affect the > behaviour of the VM subsystem if scheduling happens more frequently. I am > just guessing, I do not know. > I remember reading that a higher HZ value will make your machine more responsive, but will also mean that each running process will have a smaller CPU time slice and that the kernel will spend more CPU time scheduling at the expense of processes. HTH Liam Girdwood > Changing though trivial would require a good look at all the code that > uses HZ. > > Comments, > Balbir > > |-----Original Message----- > |From: linux-kernel-owner@vger.kernel.org > |[mailto:linux-kernel-owner@vger.kernel.org]On Behalf Of William Lee > |Irwin III > |Sent: Tuesday, April 16, 2002 1:45 PM > |To: Olaf Fraczyk > |Cc: linux-kernel@vger.kernel.org > |Subject: Re: Why HZ on i386 is 100 ? > | > | > |On Tue, Apr 16, 2002 at 09:47:48AM +0200, Olaf Fraczyk wrote: > |> Hi, > |> I would like to know why exactly this value was choosen. > |> Is it safe to change it to eg. 1024? Will it break anything? > |> What else should I change to get it working: > |> CLOCKS_PER_SEC? > |> Please CC me. > |> Regards, > |> Olaf Fraczyk > | > |I tried a few times running with HZ == 1024 for some testing (or I guess > |just to see what happened). I didn't see any problems, even without the > |obscure CLOCKS_PER_SEC ELF business. > | > | > |Cheers, > |Bill > |- > |To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > |the body of a message to majordomo@vger.kernel.org > |More majordomo info at http://vger.kernel.org/majordomo-info.html > |Please read the FAQ at http://www.tux.org/lkml/ > ---- > > **************************Disclaimer************************************ > > > > Information contained in this E-MAIL being proprietary to Wipro Limited > is 'privileged' and 'confidential' and intended for use only by the > individual or entity to which it is addressed. You are notified that any > use, copying or dissemination of the information contained in the E-MAIL > in any manner whatsoever is strictly prohibited. > > > > ******************************************************************** -- Liam Girdwood l_girdwood@bitwise.co.uk (Work) liam@nova-ioe.org (Home) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/