From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: interrupt coalescing and CSUM offload Date: Fri, 14 Sep 2012 09:32:52 -0700 Message-ID: <20120914093252.020992cc@nehalam.linuxnetplumber.net> References: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: Joakim Tjernlund Return-path: Received: from mail.vyatta.com ([76.74.103.46]:54870 "EHLO mail.vyatta.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752357Ab2INQdY (ORCPT ); Fri, 14 Sep 2012 12:33:24 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Fri, 14 Sep 2012 16:35:13 +0200 Joakim Tjernlund wrote: > > I am adding interrupt coalescing to the ucc_geth driver. Unfortunately > there is only support for RX interrupt coalescing. > I wonder if there is any way "simulate" TX interrupt coalescing? > > I am also looking at adding HWCSUM support but this device can only do > IP header CSUM offload. This doesn't seem to be an option in Linux? > As I understand it, one must do CSUM offload for the whole frame, both > IP header and TCP/UDP csums? > > Jocke There are a few drivers that turn off TX interrupt completely. They cleanup TX buffers on next send and have a timer to cleanup as well. This has performance benefits, but it does cause issues with local flow control (the freeing of skb is used to rate limit local traffic).