From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [PATCH] sky2: flow control off Date: Tue, 6 Feb 2007 19:57:57 -0800 Message-ID: <20070206195757.1bc81923@oldman> References: <20070202153425.2d979fd4@freekitty> <45C91ABF.9030504@pobox.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Stephen Hemminger , Linus Torvalds , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Andrew Morton To: Jeff Garzik Return-path: Received: from smtp.osdl.org ([65.172.181.24]:33235 "EHLO smtp.osdl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030247AbXBGD6M (ORCPT ); Tue, 6 Feb 2007 22:58:12 -0500 In-Reply-To: <45C91ABF.9030504@pobox.com> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Tue, 06 Feb 2007 19:18:07 -0500 Jeff Garzik wrote: > Stephen Hemminger wrote: > > Turn flow control off for sky2. When flow control is on, the transmitter > > may get randomly stuck. Perhaps there is hardware problem, but until > > Marvell provides errata information for workaround, it should default to off. > > > > Signed-off-by: Stephen Hemminger > > --- > > drivers/net/sky2.c | 2 +- > > 1 files changed, 1 insertions(+), 1 deletions(-) > > > > diff --git a/drivers/net/sky2.c b/drivers/net/sky2.c > > index 822dd0b..a31dea5 100644 > > --- a/drivers/net/sky2.c > > +++ b/drivers/net/sky2.c > > @@ -3263,7 +3263,7 @@ #endif > > > > /* Auto speed and flow control */ > > sky2->autoneg = AUTONEG_ENABLE; > > - sky2->flow_mode = FC_BOTH; > > + sky2->flow_mode = FC_NONE; > > I ACK the patch... conditional on some -mm style testing and user ACKs. > > Logic: if there were no downsides to disabling flow control globally, > the world's networks would have already done so. Flow control can be > quite helpful, so I while I understand the errata argument, I also want > to understand the full effect of this tiny patch. > Actually, the E1000 had it off until recently. The downside is that if a system is connected on a switch with a gigabit to 100mbit port and using a stupid protocol like NFS over UDP, then the packet burst is sure to get truncated so the 8K fragmented UDP never gets through.