From owner-cvs-all Mon Oct 21 18:20:11 2002 Delivered-To: cvs-all@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 2774D37B401; Mon, 21 Oct 2002 18:20:10 -0700 (PDT) Received: from sccrmhc01.attbi.com (sccrmhc01.attbi.com [204.127.202.61]) by mx1.FreeBSD.org (Postfix) with ESMTP id 6469143E88; Mon, 21 Oct 2002 18:20:09 -0700 (PDT) (envelope-from julian@elischer.org) Received: from InterJet.elischer.org ([12.232.206.8]) by sccrmhc01.attbi.com (InterMail vM.4.01.03.27 201-229-121-127-20010626) with ESMTP id <20021022012008.PZFD26524.sccrmhc01.attbi.com@InterJet.elischer.org>; Tue, 22 Oct 2002 01:20:08 +0000 Received: from localhost (localhost.elischer.org [127.0.0.1]) by InterJet.elischer.org (8.9.1a/8.9.1) with ESMTP id SAA26291; Mon, 21 Oct 2002 18:11:11 -0700 (PDT) Date: Mon, 21 Oct 2002 18:11:10 -0700 (PDT) From: Julian Elischer To: Kirk McKusick Cc: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/fs/specfs spec_vnops.c src/sys/kern subr_disk.c src/sys/ufs/ffs ffs_snapshot.c In-Reply-To: <200210220059.g9M0xnWm049023@repoman.freebsd.org> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-cvs-all@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On Mon, 21 Oct 2002, Kirk McKusick wrote: > mckusick 2002/10/21 17:59:49 PDT > > On the issue of scaling HZ, I believe that the current scheme is > better than using a fixed quantum of time. As machines and I/O > subsystems get faster, the resolution on the clock also rises. > So, ten years from now we will be slowing things down for shorter > periods of time, but the proportional effect on the system will > be about the same as it is today. So, I view this as a feature > rather than a drawback. Hence this patch sticks with using HZ. Rather than using a time delay, wouldn't it be possible to ensure that requests of some types can not occur back-to-back, (i.e. the disk scheduler skips them in the queue or something) and only soes requests from that source "1 in 2" or "1 in 3" or similar. I know this would result in a hi-pro and low-pri queue for the disks but that may not be such a bad idea.. Julian To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message