From owner-freebsd-hackers@FreeBSD.ORG Mon Mar 7 15:01:17 2011 Return-Path: Delivered-To: freebsd-hackers@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 5955B1065670 for ; Mon, 7 Mar 2011 15:01:17 +0000 (UTC) (envelope-from bf1783@googlemail.com) Received: from mail-yw0-f54.google.com (mail-yw0-f54.google.com [209.85.213.54]) by mx1.freebsd.org (Postfix) with ESMTP id 175ED8FC14 for ; Mon, 7 Mar 2011 15:01:16 +0000 (UTC) Received: by ywf9 with SMTP id 9so1867061ywf.13 for ; Mon, 07 Mar 2011 07:01:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=gamma; h=domainkey-signature:mime-version:reply-to:date:message-id:subject :from:to:cc:content-type; bh=cdDimqisoijpSRj87esLEl0SaHupK6PB2astnDUc3iI=; b=txpRWLUdv90dLqKUyk8gCW2rvAVfXUoEDj9WNBJhtbrvMV9ojpswBE5LKeihLIIm+1 jTUouW5KHQVanBFuJu5Fvfa/8ZYps3S6P8cy++ffu67Lt85HS2uHRDx7mOdaL1EQdhVq kdiqsdMUqynN+/EeOhF7S3O1Gqm55VKMn+cCU= DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=mime-version:reply-to:date:message-id:subject:from:to:cc :content-type; b=YOR/ACavPqstB9CzBw9Oa5ae7563lOkbJ0TIDO4xim6J9j9UId7CULUNTbLWDCVqRD tVQsZKnj85ed/SkuSXsaayrtMDtoynxNxZkq7S2sgoFLvZjE6poKot9g4fTKwQATR2LD zuM3BLpECgqF5JFtQ3gFUoEmcfSAoXoMJ+jpM= MIME-Version: 1.0 Received: by 10.236.192.130 with SMTP id i2mr6083567yhn.37.1299510076281; Mon, 07 Mar 2011 07:01:16 -0800 (PST) Received: by 10.236.108.44 with HTTP; Mon, 7 Mar 2011 07:01:16 -0800 (PST) Date: Mon, 7 Mar 2011 15:01:16 +0000 Message-ID: From: "b. f." To: Martin Birgmeier Content-Type: text/plain; charset=ISO-8859-1 Cc: freebsd-hackers@FreeBSD.org Subject: Re: All CPUs always running at profhz X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: bf1783@gmail.com List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 07 Mar 2011 15:01:17 -0000 > I have systems running 7.4 and 8.2. The newer ones (in terms of age of > hardware) are always running at profhz, i.e., when executing a "systat > -vm 1" I see that all cores always get profhz interrupts per second. > > An older machine running 7.4 is running at hz (which for this machine I > set to kern.hz=200 in loader.conf). > > Using ps -o ...,flags,... I see that no process has profiling turned on. > > Why is this so? > > Especially on laptops, I'd like to save power by lowering the interrupt > rate. I have not analyzed this problem. However, by using 9-CURRENT, together with http://people.freebsd.org/~mav/tm6292_idle.patch , removing DEVICE_POLLING from my kernel, and reducing kern.hz to 100, I was able to achieve reported interrupt rates of ~35-40 Hz on my UP machines when idle, and substantial reductions when the machines were loaded, as well. When used with other power-saving measures, this was a big help. b.