Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 10 Jul 2002 20:26:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 10 Jul 2002 20:26:56 -0400 Received: from sj-msg-core-2.cisco.com ([171.69.24.11]:5018 "EHLO sj-msg-core-2.cisco.com") by vger.kernel.org with ESMTP id ; Wed, 10 Jul 2002 20:26:56 -0400 Message-Id: <5.1.0.14.2.20020711102614.0209de60@mira-sjcm-3.cisco.com> X-Mailer: QUALCOMM Windows Eudora Version 5.1 Date: Thu, 11 Jul 2002 10:28:41 +1000 To: Andrew Morton From: Lincoln Dale Subject: Re: HZ, preferably as small as possible Cc: "Grover, Andrew" , Linux In-Reply-To: <3D2CA6E3.CB5BC420@zip.com.au> References: <59885C5E3098D511AD690002A5072D3C02AB7F88@orsmsx111.jf.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 884 Lines: 25 At 02:28 PM 10/07/2002 -0700, Andrew Morton wrote: > > But on the other hand, increasing HZ has perf/latency benefits, yes? Have > > these been quantified? > >Not that I'm aware of. And I'd regard any such claims with some >scepticism. for one, i'm using a modified version of the network FIFO queue discipline to inject "delay" and "drop", similar to what ippipe can do on FreeBSD. given i'm using a kernel timer for this, HZ >= 1000 is essential for <1.5 millisecond accuracy. perhaps we really need a high-speed timer mechanism for parts of the kernel that require it (or a highly-accurate single-fire timer)? cheers, lincoln. - 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/