From mboxrd@z Thu Jan 1 00:00:00 1970 From: Giuseppe CAVALLARO Subject: stmmac mitigation and ethtool coalesce parameters Date: Wed, 22 Aug 2012 09:14:00 +0200 Message-ID: <503486B8.7080706@st.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit To: ML netdev Return-path: Received: from eu1sys200aog114.obsmtp.com ([207.126.144.137]:46557 "EHLO eu1sys200aog114.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751460Ab2HVHOQ (ORCPT ); Wed, 22 Aug 2012 03:14:16 -0400 Received: from zeta.dmz-eu.st.com (zeta.dmz-eu.st.com [164.129.230.9]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id C81ACF6 for ; Wed, 22 Aug 2012 07:14:01 +0000 (GMT) Received: from mail7.sgp.st.com (mail7.sgp.st.com [164.129.223.81]) by zeta.dmz-eu.st.com (STMicroelectronics) with ESMTP id 6D4FF2452 for ; Wed, 22 Aug 2012 07:14:01 +0000 (GMT) Sender: netdev-owner@vger.kernel.org List-ID: Hello I'm reworking the mitigation schema in the stmmac and removing the old and dead STMMAC_TIMER code. On new chips we have an HW RX-Watchdog that can be used for mitigating the Rx-interrupts and first results look promising. Before posting the patches I have a doubt about the ethtool coalesce parameters to use in the driver to tune the following parameters: - On Rx-side I have: a parameter that is the RI Watchdog Timer count. It indicates the number of system clock cycles. - On Tx-side, the mitigation schema I'm using is based on a SW timer that calls the tx function (stmmac_tx) to reclaim the resource after transmitting the frames. Also there is another parameter (like a threshold) used to program the descriptors avoiding to set the interrupt on completion bit in when the frame is sent (xmit). This means that the stmmac_tx can be called by the ISR too. This approach is showing really good figures as well. so I wonder which are the appropriate ethtool coalesce parameters to use? Or could I tune them by using sysfs entries? Welcome advice. Peppe