From owner-freebsd-questions@FreeBSD.ORG Tue Feb 3 21:19:00 2009 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id EDCE8106566B for ; Tue, 3 Feb 2009 21:19:00 +0000 (UTC) (envelope-from gfritz@gmail.com) Received: from fg-out-1718.google.com (fg-out-1718.google.com [72.14.220.159]) by mx1.freebsd.org (Postfix) with ESMTP id 766268FC16 for ; Tue, 3 Feb 2009 21:19:00 +0000 (UTC) (envelope-from gfritz@gmail.com) Received: by fg-out-1718.google.com with SMTP id l26so880740fgb.35 for ; Tue, 03 Feb 2009 13:18:59 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:received:date:from:to:subject :message-id:mime-version:content-type:content-disposition:user-agent; bh=8htJNmp38W7EZfhlxbE7442KXaTu7rkxBcPwjZAsz4Y=; b=sg6AAVm+FHZmQx6AYK6naF8+j5tWKwvxjKDMUtQjsjmBgABfJQ3FdSEOrXmWvInybB ypqOUr2WyYKhq3oVc+qT7loDG2dp86DKBDonAJ91jaXxXy6vW3gvvNZxPVE6fDfw1+HQ k+Q5EJHGTWhjq8UCg6MnHdQkfS+GmY9tWYeI8= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:subject:message-id:mime-version:content-type :content-disposition:user-agent; b=Xxbhgld1LxjMon4BeDAijr1DII/lE3Odo53oCON7vrHaotG6o2xGfY+TDQBVfgASj0 n4t8VYbmdiDM1e3ExtYg+/vMf3C9NEFKPgyantbHt35BR5Fk/9osQvoCMKvssSf0fggS nEHB1tYpwItclSGlshJcWDd9OtcgSDJJQ3pwA= Received: by 10.223.105.139 with SMTP id t11mr3098415fao.11.1233695939515; Tue, 03 Feb 2009 13:18:59 -0800 (PST) Received: from dev.null (80-175-174-206.cust.wirelessbeehive.com [206.174.175.80]) by mx.google.com with ESMTPS id h1sm3576236nfh.63.2009.02.03.13.18.57 (version=TLSv1/SSLv3 cipher=RC4-MD5); Tue, 03 Feb 2009 13:18:58 -0800 (PST) Received: by dev.null (Postfix, from userid 1002) id 6D7C916AA; Tue, 3 Feb 2009 14:18:51 -0700 (MST) Date: Tue, 3 Feb 2009 14:18:51 -0700 From: Geoff Fritz To: freebsd-questions@freebsd.org Message-ID: <20090203211851.GA92202@dev.null> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.18 (2008-05-17) Subject: Scheduling behavior when using idprio X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 03 Feb 2009 21:19:01 -0000 I recently noticed something odd. Whenever I have a cpu-bound process (say, piping a lot of data through "gzip -9c") that's been given an idle priority using "idprio 31 -", I notice that my system's overall interactive responsiveness feels peppier. Apps seems to respond faster, screens redraw faster, web pages render quicker, etc.. It's reminiscent of enabling the interactive real-time options in the Linux kernel (at least, as I remember it years ago from the 2.4 days). My system is a little long in the tooth (2GHz Athlon64, single core), so any speed improvements are quickly noticed around here. I was wondering if there was an explanation for my observations, or if anyone else has seen -- or could repeat -- this. If this is a repeatable/known behavior, would this be a scheduler bug? Why would things run more smoothly only when there was a single ulta-low priority process running? Thanks. -- Geoff