From owner-freebsd-net@FreeBSD.ORG  Fri Oct 14 19:19:32 2005
Return-Path: <owner-freebsd-net@FreeBSD.ORG>
X-Original-To: net@FreeBSD.org
Delivered-To: freebsd-net@FreeBSD.ORG
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id 0E40E16A41F
	for <net@FreeBSD.org>; Fri, 14 Oct 2005 19:19:32 +0000 (GMT)
	(envelope-from gallatin@cs.duke.edu)
Received: from duke.cs.duke.edu (duke.cs.duke.edu [152.3.140.1])
	by mx1.FreeBSD.org (Postfix) with ESMTP id 26C6843D53
	for <net@FreeBSD.org>; Fri, 14 Oct 2005 19:19:27 +0000 (GMT)
	(envelope-from gallatin@cs.duke.edu)
Received: from grasshopper.cs.duke.edu (grasshopper.cs.duke.edu [152.3.145.30])
	by duke.cs.duke.edu (8.13.4/8.13.4) with ESMTP id j9EJJPj5012542
	(version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO);
	Fri, 14 Oct 2005 15:19:25 -0400 (EDT)
Received: (from gallatin@localhost)
	by grasshopper.cs.duke.edu (8.12.9p2/8.12.9/Submit) id j9EJJJhL013625; 
	Fri, 14 Oct 2005 15:19:19 -0400 (EDT) (envelope-from gallatin)
From: Andrew Gallatin <gallatin@cs.duke.edu>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Message-ID: <17232.1207.615226.432579@grasshopper.cs.duke.edu>
Date: Fri, 14 Oct 2005 15:19:19 -0400 (EDT)
To: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: <31823.1129304673@critter.freebsd.dk>
References: <17231.50841.442047.622878@grasshopper.cs.duke.edu>
	<31823.1129304673@critter.freebsd.dk>
X-Mailer: VM 6.75 under 21.1 (patch 12) "Channel Islands" XEmacs Lucid
Cc: Garrett Wollman <wollman@csail.mit.edu>, net@FreeBSD.org
Subject: Re: Call for performance evaluation: net.isr.direct (fwd) 
X-BeenThere: freebsd-net@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Networking and TCP/IP with FreeBSD <freebsd-net.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-net>,
	<mailto:freebsd-net-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-net>
List-Post: <mailto:freebsd-net@freebsd.org>
List-Help: <mailto:freebsd-net-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-net>,
	<mailto:freebsd-net-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 14 Oct 2005 19:19:32 -0000


Poul-Henning Kamp writes:
 > The solution is not faster but less reliable timekeeping, the
 > solution is to move the scheduler(s) away from using time as an
 > approximation of cpu cycles.

So you mean rather than use binuptime() in mi_switch(), use some
per-cpu cycle counter (like rdtsc)?

Heck, why not just use ticks for the scheduler and keep the expensive
timekeeping code out of the critical path altogether?  Does it really
need better than 1ms resolution?

Drew