From owner-freebsd-current@FreeBSD.ORG Thu Oct 9 17:08:07 2003 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 9130D16A4B3 for ; Thu, 9 Oct 2003 17:08:07 -0700 (PDT) Received: from ebb.errno.com (ebb.errno.com [66.127.85.87]) by mx1.FreeBSD.org (Postfix) with ESMTP id C697243FAF for ; Thu, 9 Oct 2003 17:08:04 -0700 (PDT) (envelope-from sam@errno.com) Received: from 66.127.85.92 ([66.127.85.92]) (authenticated bits=0) by ebb.errno.com (8.12.9/8.12.9) with ESMTP id h9A07x0x029702 (version=TLSv1/SSLv3 cipher=RC4-MD5 bits=128 verify=NO); Thu, 9 Oct 2003 17:08:03 -0700 (PDT) (envelope-from sam@errno.com) From: Sam Leffler Organization: Errno Consulting To: "Michael O. Boev" , "Terry Lambert" Date: Thu, 9 Oct 2003 17:13:58 -0700 User-Agent: KMail/1.5.2 References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200310091713.58815.sam@errno.com> cc: freebsd-current@freebsd.org Subject: Re: Why is em nic generating interrupts? X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 10 Oct 2003 00:08:07 -0000 On Thursday 09 October 2003 05:57 am, Michael O. Boev wrote: > > -----Original Message----- > > From: Terry Lambert [mailto:tlambert2@mindspring.com] > > Sent: Thursday, October 09, 2003 5:19 PM > > To: Michael O. Boev > > Cc: freebsd-current@FreeBSD.ORG > > Subject: Re: Why is em nic generating interrupts? > > > > "Michael O. Boev" wrote: > > > I've got a [uniprocessor 5.1-RELEASE] router machine with fxp > > > > and em nics. > > > > > I've built my kernel with the following included: > > > > > > options DEVICE_POLLING > > > options HZ=2500 > > > > > > and enabled polling in /etc/sysctl.conf. > > > > [ ... ] > > > > > What's happening? Is polling working in my case? > > > If yes, why is vmstat showing interrupts? I see clearly, > > > that fxp's counter doesn't increase, and em's is constantly growing. > > > > > > Is there anyone who knows for sure that em's polling works? > > > > You may want to ask Luigi; polling is his code. > > > > However, I believe the issue is that polling doesn't start > > until you take an interrupt, and it stops as soon as there is > > no more data to process, and waits for the next interrupt. > > > > If you were to jack your load way up, you would probably see > > an increase in interrupts, then them dropping off dramatically. > > To this dare I object, that there is traffic going through this machine, > and fxp0 is NOT generating interrupts, while em IS. So, if the rule above > works, they both have to behave in same ways. > > > If all else fails, read the source code... 8-). > > )) I've tried to, but... had to ask here. So all is left is to ask Luigi > and Intel. I cannot comment on 5.1-R, but I am running DEVICE_POLLING tests today with -current and 2 em NICS and systat -vm shows no interrupts for the IRQs where the NICs are. I can only guess that either 5.1-R has a bug or the polling support was not in the driver at that point. Sam