Date: Mon, 22 Sep 2003 16:11:14 +0200 (CEST) From: Harti Brandt <brandt@fokus.fraunhofer.de> To: "M. Warner Losh" <imp@bsdimp.com> Cc: freebsd-arch@freebsd.org Subject: Re: interrupt latency and driver locking Message-ID: <20030922160106.Y6621@beagle.fokus.fraunhofer.de> In-Reply-To: <20030920.214835.101559646.imp@bsdimp.com> References: <20030920141158.B97439@xorpc.icir.org> <XFMail.20030920142934.jdp@polstra.com> <20030920.214835.101559646.imp@bsdimp.com>
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On Sat, 20 Sep 2003, M. Warner Losh wrote: MWL>In message: <XFMail.20030920142934.jdp@polstra.com> MWL> John Polstra <jdp@polstra.com> writes: MWL>: there will be no link changes except at bootstrap and shutdown. MWL> MWL>For server machines. For laptops, these events happen more often. MWL>However, for most laptops, the rate that they happen is typically on MWL>less than 1/hour. Still rare enough to not worry about optimizing it MWL>and your other points are good. I just wanted to make sure that it MWL>wasn't optimized to the point where disconnecting the cable from the MWL>laptop to move it accross the room, or another room doesn't cause huge MWL>problems. Perhaps the polling should be configurable., I struggled with this a year ago in the xl driver. I have an application that does real-time satellite simulation over two ethernet links with HZ=10000. This works really perfect (timing errors are not larger than 200usecs) except for the MII polling. With help from msilby we could cut down the mii polling delay from 8msecs to below 1msec. But, because that's still too much for my application, I have simply commented out the polling calls in the mii source. I suppose there are other application (servers) where one could simply switch them off. This could perhaps be done with a sysctl in mii(4). harti -- harti brandt, http://www.fokus.fraunhofer.de/research/cc/cats/employees/hartmut.brandt/private brandt@fokus.fraunhofer.de, harti@freebsd.org
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