From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262177AbUK0ESn (ORCPT ); Fri, 26 Nov 2004 23:18:43 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262246AbUK0EOS (ORCPT ); Fri, 26 Nov 2004 23:14:18 -0500 Received: from lucidpixels.com ([66.45.37.187]:42725 "HELO lucidpixels.com") by vger.kernel.org with SMTP id S262110AbUKZTNz (ORCPT ); Fri, 26 Nov 2004 14:13:55 -0500 Date: Fri, 26 Nov 2004 07:07:12 -0500 (EST) From: Justin Piszcz X-X-Sender: jpiszcz@p500 To: Robert Olsson cc: linux-kernel@vger.kernel.org Subject: Re: CONFIG_TULIP_NAPI_HW_MITIGATION latency question. In-Reply-To: <16806.1163.601015.670054@robur.slu.se> Message-ID: References: <16806.1163.601015.670054@robur.slu.se> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Thanks for the info. On Thu, 25 Nov 2004, Robert Olsson wrote: > > > > Justin Piszcz writes: > > "at the cost of a small latency" > > > > How much additional latency is added with this option enabled? > > > > 5ms? 10ms? > > > > -> Use Interrupt Mitigation > > x CONFIG_TULIP_NAPI_HW_MITIGATION: > > x Use HW to reduce RX interrupts. Not strict necessary since NAPI > > reduces RX interrupts but itself. Although this reduces RX interrupts even at > > low levels traffic at the cost of a small latency. > > x > > x If in doubt, say Y. > > Hello! > > It's in usec and the tulip only enables this latency when it's needed it > really tries to keep latency down. > > It has three steeps of input control. > > Low rate: No driver latency. No interrupt delay at all. > Medium rate: Samll driver latency. > High rate: Polling via ->poll > > --ro >