Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763598AbXHXQvj (ORCPT ); Fri, 24 Aug 2007 12:51:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760215AbXHXQvP (ORCPT ); Fri, 24 Aug 2007 12:51:15 -0400 Received: from e32.co.us.ibm.com ([32.97.110.150]:32908 "EHLO e32.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759693AbXHXQvN (ORCPT ); Fri, 24 Aug 2007 12:51:13 -0400 Date: Fri, 24 Aug 2007 11:51:10 -0500 To: Stephen Hemminger Cc: Jan-Bernd Themann , Thomas Klein , Marcus@ozlabs.org, Jan-Bernd Themann , netdev , linux-kernel , Christoph Raisch , linux-ppc , akepner@sgi.com, Eder , Stefan Roscher Subject: Re: RFC: issues concerning the next NAPI interface Message-ID: <20070824165110.GH4282@austin.ibm.com> References: <200708241559.17055.ossthema@de.ibm.com> <20070824153703.GN5592@sgi.com> <200708241747.16592.ossthema@de.ibm.com> <20070824085203.42f4305c@freepuppy.rosehill.hemminger.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070824085203.42f4305c@freepuppy.rosehill.hemminger.net> User-Agent: Mutt/1.5.11 From: linas@austin.ibm.com (Linas Vepstas) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1084 Lines: 21 On Fri, Aug 24, 2007 at 08:52:03AM -0700, Stephen Hemminger wrote: > > You need hardware support for deferred interrupts. Most devices have it (e1000, sky2, tg3) > and it interacts well with NAPI. It is not a generic thing you want done by the stack, > you want the hardware to hold off interrupts until X packets or Y usecs have expired. Just to be clear, in the previous email I posted on this thread, I described a worst-case network ping-pong test case (send a packet, wait for reply), and found out that a deffered interrupt scheme just damaged the performance of the test case. Since the folks who came up with the test case were adamant, I turned off the defferred interrupts. While defferred interrupts are an "obvious" solution, I decided that they weren't a good solution. (And I have no other solution to offer). --linas - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/