From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from ozlabs.org ([203.10.76.45]:45017 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751432AbYEPDOI (ORCPT ); Thu, 15 May 2008 23:14:08 -0400 From: Rusty Russell To: David Miller Subject: Re: [PATCH] mac80211: rewrite fragmentation code Date: Fri, 16 May 2008 12:01:48 +1000 Cc: herbert@gondor.apana.org.au, mb@bu3sch.de, johannes@sipsolutions.net, linux-wireless@vger.kernel.org, netdev@vger.kernel.org, ron.rindjunsky@intel.com, tomasw@gmail.com, ivdoorn@gmail.com, peter.p.waskiewicz.jr@intel.com References: <20080507130548.GA26977@gondor.apana.org.au> <20080508032208.GA401@gondor.apana.org.au> <20080507.202606.242037993.davem@davemloft.net> In-Reply-To: <20080507.202606.242037993.davem@davemloft.net> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Message-Id: <200805161201.48835.rusty@rustcorp.com.au> (sfid-20080516_051440_602223_EE554220) Sender: linux-wireless-owner@vger.kernel.org List-ID: On Thursday 08 May 2008 13:26:06 David Miller wrote: > From: Herbert Xu > Date: Thu, 8 May 2008 11:22:08 +0800 > > > On Wed, May 07, 2008 at 03:48:06PM +0200, Michael Buesch wrote: > > > So there's no way to actually fail in a TX handler? Drivers > > > are doomed to drop the packet, if they cannot handle it due to > > > ring overflow? > > > > You're supposed to stop the queue before the ring overflows. > > Right, and this is why drivers choose a TX wakeup threshold such > that they can accept an arbitrarily sized TSO frame. Dave, please allow me to ask a heretical question. Returning TX_BUSY has some appeal for virtio_net: is it fundamentally a flawed idea, or simply a matter of coding? Currently we have no virtio interface to ask how many descriptors are left; it's not clear that it's a fair question to ask, since for Xen it's depends on the actual buffers we're trying to put in the descirptors. Thanks, Rusty.