From owner-freebsd-hackers@FreeBSD.ORG Thu Jul 25 16:11:39 2013 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTP id BE406CF8; Thu, 25 Jul 2013 16:11:39 +0000 (UTC) (envelope-from adrian.chadd@gmail.com) Received: from mail-wg0-x234.google.com (mail-wg0-x234.google.com [IPv6:2a00:1450:400c:c00::234]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 04C32217E; Thu, 25 Jul 2013 16:11:38 +0000 (UTC) Received: by mail-wg0-f52.google.com with SMTP id b13so1846798wgh.19 for ; Thu, 25 Jul 2013 09:11:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type; bh=giv0WWIGpI3VrGnbHPt7xc3L6V+CXUsSA5jYbeAPgZY=; b=EcvK1suJsy8bt/l9zJ+y0GrDG4zuukGuxdOqOZw2SkiDjGKH+vaneXYK5SJ5eGZ5X8 YhGoY0Tqn01NIeFbYriDBAYdYHrmQ/wC8X6Pn8rIy/72J/ho/YPUnL7CtNKVP2oYvQin oR1F3f3TCkk+uldjlmf9tmHVYd7zfMliqxzSlubruBXGAm6pVHAVha2FP+gXiVks38BD a/qsv9IAZQ+SeUnBnHLfm1xqlGiBRgxOaNnhu8nGWO3Xxx7/1vRQ9WFQYuXJX2wq+9j8 LaDMlcFnplZmx4hae25jiMZD2x+xLQWUMLrK5vltU7I6oOl/wTpVuOtbfbEDMCG0jQE1 eKWg== MIME-Version: 1.0 X-Received: by 10.194.92.6 with SMTP id ci6mr7227233wjb.79.1374768697270; Thu, 25 Jul 2013 09:11:37 -0700 (PDT) Sender: adrian.chadd@gmail.com Received: by 10.217.94.132 with HTTP; Thu, 25 Jul 2013 09:11:37 -0700 (PDT) In-Reply-To: References: Date: Thu, 25 Jul 2013 09:11:37 -0700 X-Google-Sender-Auth: -vAecfRGuNGwy-4rjpi6FHKbS4E Message-ID: Subject: Re: Kern.hz= +1 hertz at anything 2500 and above. From: Adrian Chadd To: Wojciech Puchar Content-Type: text/plain; charset=ISO-8859-1 Cc: Super Bisquit , freebsd-current , FreeBSD Hackers , FreeBSD PowerPC ML X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 25 Jul 2013 16:11:39 -0000 On 25 July 2013 02:51, Wojciech Puchar wrote: >> improved with a higher kern.hz rating. Unless the future holds an emu20k2, >> there will be RAM used from the motherboard. >> 1. I will need a real-time or a faster kernel- hence the high rate wanted- >> because the devices to be built will be used in an active environment: >> art, >> music, audio control. >> 2. Any system with limited memory and a low CPU hertz rate benefits from >> the higher kern.hz setting. > rather opposite. more kern.hz=more interrupts. Right. More hz == more interrupts and less ability for a CPU-bound process to chew all the CPU. So is it a scheduling issue, where you have multiple CPU bound userland processes that aren't being fair and consuming all the CPU? Is it that your device driver(s) aren't interrupting correctly, relying on the hz tick to make up the slack, etc. Is it a busted halt loop, which is being papered over with hz ticks? Have you tried -10 on that kit, with the more aggressive clock/timer code that won't interrupt unless it needs to? Has that changed things? -adrian