From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH 1/1] TX throttling bug-fixing patch of AX88179_178A Date: Mon, 22 Jul 2013 11:47:21 -0700 Message-ID: <1374518841.4990.26.camel@edumazet-glaptop> References: <1374311809-4155-1-git-send-email-freddy@asix.com.tw> <1374512879.4990.19.camel@edumazet-glaptop> <1374518312.1635.29.camel@bwh-desktop.uk.level5networks.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Grant Grundler , Freddy Xin , David Miller , netdev , linux-usb@vger.kernel.org, LKML , ASIX Louis =?UTF-8?Q?=5B=E8=98=87=E5=A8=81=E9=99=B8=5D?= , Allan Chou To: Ben Hutchings Return-path: In-Reply-To: <1374518312.1635.29.camel@bwh-desktop.uk.level5networks.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Mon, 2013-07-22 at 19:38 +0100, Ben Hutchings wrote: > On Mon, 2013-07-22 at 11:29 -0700, Grant Grundler wrote: > > On Mon, Jul 22, 2013 at 10:07 AM, Eric Dumazet wrote: > > ... > > > I guess that if a driver does not advertise NETIF_F_SG, this > > > skb_linearize() call is not needed : All frames reaching your xmit > > > function should already be linear > > > > As Ben Hutchings pointed out, hw_features is still setting this...but > > I'm not sure how that matters. > > > > ax88179_set_features() doesn't allow setting SG or TSO features. But > > I expect it would be "not too difficult" to add such that ethtool > > could set those features after boot. > [...] > > It already can. That's what putting feature flags in hw_features does. My original concern, that inspired this patch, was to remove SG support, as this driver does not have SG support at all. Linearize a full TSO packet needs order-5 allocations, thats likely to fail and lead to very slow TCP performance, because it will only rely on retransmits.