From owner-freebsd-hackers@FreeBSD.ORG Thu Nov 20 13:15:32 2003 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 0B63E16A4CF for ; Thu, 20 Nov 2003 13:15:32 -0800 (PST) Received: from mail.sandvine.com (sandvine.com [199.243.201.138]) by mx1.FreeBSD.org (Postfix) with ESMTP id 1C7A943F3F for ; Thu, 20 Nov 2003 13:15:31 -0800 (PST) (envelope-from don@sandvine.com) Received: by mail.sandvine.com with Internet Mail Service (5.5.2657.72) id ; Thu, 20 Nov 2003 16:15:29 -0500 Message-ID: From: Don Bowman To: 'Avleen Vig' , Don Bowman Date: Thu, 20 Nov 2003 16:15:19 -0500 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2657.72) Content-Type: text/plain; charset="iso-8859-1" cc: freebsd-hackers@freebsd.org Subject: RE: Device polling, with SMP? X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 20 Nov 2003 21:15:32 -0000 From: Avleen Vig [mailto:lists-freebsd@silverwraith.com] > On Thu, Nov 20, 2003 at 12:58:58PM -0500, Don Bowman wrote: > > > I read Luigi's paper at info.iet.unipi.it/~luigi/polling/ > which at the > > > end implies that DEVICE_POLLING on an SMP box might not make > > > sense - but > > > right now for me it would make sense as both CPU's are locked: > > > One tries to handle interrupts > > > The other tries to manage the application > > > > > > I could try forcing DEVICE_POLLING to compile as is > suggested in that > > > URL but I wanted to see if anyone had tried this before. > > > The interface is an FXP. > > > > We use it on em. I just commented out the #error line that > > says you can't do it. > > device polling in idle doesn't work, and the user/system time > > calculation isn't correct, but it works well otherwise. > > This is pretty much what I wanted to confirm thanks! > In which way is the system/user time incorrect? Always, or only under > high load? what about it is incorrect? My skills are limited > but I might > take a stab at fixing that. Well, on -STABLE, there can be only one CPU active in the kernel. Thus on a 2-way HTT system, the system thinks there are 4 processors, but there is no way to get 'system' cpu to exceed 25%. So in polling, the 'user frac' and 'kernel frac' are very difficult to understand. --don