From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: xennet: skb rides the rocket: 20 slots Date: Tue, 8 Jan 2013 17:04:28 -0500 Message-ID: <20130108220428.GA17064@phenom.dumpdata.com> References: <72958707.20130104172854@eikelenboom.it> <1357556115.7989.13.camel@zakaz.uk.xensource.com> <50EB8091.90705@oracle.com> <1357639549.7989.147.camel@zakaz.uk.xensource.com> <6035A0D088A63A46850C3988ED045A4B35598AD6@BITCOM1.int.sbss.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <6035A0D088A63A46850C3988ED045A4B35598AD6@BITCOM1.int.sbss.com.au> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: James Harper Cc: Sander Eikelenboom , ANNIE LI , Ian Campbell , xen-devel List-Id: xen-devel@lists.xenproject.org On Tue, Jan 08, 2013 at 08:57:19PM +0000, James Harper wrote: > > > If netback complains about "Too many frags", then it should be > > > MAX_SKB_FRAGS limitation in netback results in dropping packets in > > > netfront. It is possible that other netfronts(windows?) also hit this. > > > > It's very possible. I rather suspect that non-Linux frontends have > > workarounds (e.g. manual resegmenting etc) for this case. > > > > GPLPV gathers fragments together if there are too many. Mostly this is just the header but there could be a whole lot of copying going on in a worst-case packet. > > It would be nice if a max-frags value was written to xenstore... do different backends (solaris? Bsd?) have different requirements? Or maybe that's already been discussed - I haven't followed this thread closely. I think we discussed it last year as something that should be exported via XenBus. But never got down to figure out what it entails in - I think. This was pre-holidays. > > James