From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261337AbULMUSp (ORCPT ); Mon, 13 Dec 2004 15:18:45 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262363AbULMUPQ (ORCPT ); Mon, 13 Dec 2004 15:15:16 -0500 Received: from caramon.arm.linux.org.uk ([212.18.232.186]:36101 "EHLO caramon.arm.linux.org.uk") by vger.kernel.org with ESMTP id S262340AbULMULt (ORCPT ); Mon, 13 Dec 2004 15:11:49 -0500 Date: Mon, 13 Dec 2004 20:11:43 +0000 From: Russell King To: Alan Cox , Stefan Seyfried , Con Kolivas , Pavel Machek , Linux Kernel Mailing List , Andrea Arcangeli Subject: Re: dynamic-hz Message-ID: <20041213201142.G24748@flint.arm.linux.org.uk> Mail-Followup-To: Alan Cox , Stefan Seyfried , Con Kolivas , Pavel Machek , Linux Kernel Mailing List , Andrea Arcangeli References: <20041211142317.GF16322@dualathlon.random> <20041212163547.GB6286@elf.ucw.cz> <20041212222312.GN16322@dualathlon.random> <41BCD5F3.80401@kolivas.org> <41BD483B.1000704@suse.de> <20041213135820.A24748@flint.arm.linux.org.uk> <1102949565.2687.2.camel@localhost.localdomain> <20041213162355.E24748@flint.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <20041213162355.E24748@flint.arm.linux.org.uk>; from rmk+lkml@arm.linux.org.uk on Mon, Dec 13, 2004 at 04:23:55PM +0000 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 13, 2004 at 04:23:55PM +0000, Russell King wrote: > There is another twist here though - the Linux kernel kicks itself out > of idle mode and into some other thread multiple times a second while > the system is idle. So far, in all my Linux kernel experience, I've > yet to see a kernel where it's possible to stay in the idle thread > for more than half a second. (The ARM kernels I run are always > configured with IDLE LED support, so I can _see_ when it gets kicked > out of the idle thread.) For futher information only, analysing this further, we keep switching to the events/0 thread, and it seems to be mainly for: - cursor handling every 200ms - slab cache reaping about every 2s The cursor timer is firing all the time that you have a fbcon console registered, whether or not the cursor should be displayed. Someone looking to save power should probably tackle this such that the cursor timer doesn't needlessly fire. But I guess the cellphone people would be more interested in this problem than the big iron desktop-breaking in-need-of-three-phase-supply boxen. 8) -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 PCMCIA - http://pcmcia.arm.linux.org.uk/ 2.6 Serial core