Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751328AbVK2GzP (ORCPT ); Tue, 29 Nov 2005 01:55:15 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751331AbVK2GzP (ORCPT ); Tue, 29 Nov 2005 01:55:15 -0500 Received: from smtp015.mail.yahoo.com ([216.136.173.59]:42842 "HELO smtp015.mail.yahoo.com") by vger.kernel.org with SMTP id S1751328AbVK2GzO (ORCPT ); Tue, 29 Nov 2005 01:55:14 -0500 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com.au; h=Received:Message-ID:Date:From:User-Agent:X-Accept-Language:MIME-Version:To:CC:Subject:References:In-Reply-To:Content-Type:Content-Transfer-Encoding; b=r8fxECqZVO/sQJBNnqzYLtQ/JNmdJNwycEmbnnpowtZgV8dLBdoF5E1aGcz2zSVcz6KLiYnNOQ2QLI3cA5WqONa4WyaMuMchLkYGSJPMVmupP/SIDUJkp25fEQVvCakyL27Z3Py426rvXMIDl7ldVdOllcooowG0xFUspowvWL4= ; Message-ID: <438BFB44.2080208@yahoo.com.au> Date: Tue, 29 Nov 2005 17:55:00 +1100 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12) Gecko/20051007 Debian/1.7.12-1 X-Accept-Language: en MIME-Version: 1.0 To: Ingo Molnar CC: Andrew Morton , Steven Rostedt , acpi-devel@lists.sourceforge.net, len.brown@intel.com, nando@ccrma.Stanford.EDU, rlrevell@joe-job.com, linux-kernel@vger.kernel.org, paulmck@us.ibm.com, kr@cybsft.com, tglx@linutronix.de, pluto@agmk.net, john.cooper@timesys.com, bene@linutronix.de, dwalker@mvista.com, trini@kernel.crashing.org, george@mvista.com Subject: Re: [RFC][PATCH] Runtime switching of the idle function [take 2] References: <20051118220755.GA3029@elte.hu> <1132353689.4735.43.camel@cmn3.stanford.edu> <1132367947.5706.11.camel@localhost.localdomain> <20051124150731.GD2717@elte.hu> <1132952191.24417.14.camel@localhost.localdomain> <20051126130548.GA6503@elte.hu> <1133232503.6328.18.camel@localhost.localdomain> <20051128190253.1b7068d6.akpm@osdl.org> <1133235740.6328.27.camel@localhost.localdomain> <20051128200108.068b2dcd.akpm@osdl.org> <20051129064420.GA15374@elte.hu> In-Reply-To: <20051129064420.GA15374@elte.hu> 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 Content-Length: 1595 Lines: 42 Ingo Molnar wrote: > * Andrew Morton wrote: > > >>>The way to solve this was to set >>> idle=poll. The original patch I sent was to allow the user to change to >>> idle=poll dynamically. This way they could switch to the poll_idle and >>> run there tests (requiring tsc not to drift) and then switch back to the >>> default idle to save on electricity. >> >>Use gettimeofday()? >> >>If it's just for some sort of instrumentation, run NR_CPUS instances >>of a niced-down busyloop, pin each one to a different CPU? That way >>the idle function doesn't get called at all.. > > > idle=poll is also frequently done for performance reasons [it reduces > idle wakeup latency by 10 usecs] - while it could be turned off if the > system has been idle for some time. E.g. cpufreqd could sample idle time > and turn on/off idle=poll. High-performance setups could enable it all > the time. > > as long as it can be done with zero-cost, i dont see why Steven's patch > wouldnt be a plus for us. It's a performance thing, and having runtime > switches for seemless performance features cannot be bad. > Why not just slightly cleanup and extend (eg. to ACPI) the hlt_counter thingy that many architectures already have? Nick -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com - 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/