From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zoltan Kiss Subject: Re: [PATCH net] xen-netback: Fix handling of skbs requiring too many slots Date: Wed, 4 Jun 2014 16:53:18 +0100 Message-ID: <538F40EE.2040609@citrix.com> References: <1401827406-9341-1-git-send-email-zoltan.kiss@citrix.com> <063D6719AE5E284EB5DD2968C1650D6D17256EE9@AcuExch.aculab.com> <538EF1B3.40904@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Cc: "netdev@vger.kernel.org" , "david.vrabel@citrix.com" , "davem@davemloft.net" To: David Laight , "xen-devel@lists.xenproject.org" , "ian.campbell@citrix.com" , "wei.liu2@citrix.com" , "paul.durrant@citrix.com" , "linux@eikelenboom.it" Return-path: Received: from smtp02.citrix.com ([66.165.176.63]:56048 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751592AbaFDPxW (ORCPT ); Wed, 4 Jun 2014 11:53:22 -0400 In-Reply-To: <538EF1B3.40904@citrix.com> Sender: netdev-owner@vger.kernel.org List-ID: On 04/06/14 11:15, Zoltan Kiss wrote: > On 04/06/14 09:50, David Laight wrote: >> From: netdev-owner@vger.kernel.org >>> A recent commit (a02eb4 "xen-netback: worse-case estimate in >>> xenvif_rx_action is >>> underestimating") capped the slot estimation to MAX_SKB_FRAGS, but >>> that triggers >>> the next BUG_ON a few lines down, as the packet consumes more slots than >>> estimated. >>> This patch introduces full_coalesce on the skb callback buffer, which >>> is used in >>> start_new_rx_buffer() to decide whether netback needs coalescing more >>> aggresively. By doing that, no packet should need more than >>> XEN_NETIF_MAX_TX_SIZE / PAGE_SIZE data slots, as the provided buffers >>> are fully >>> utilized. >> ... >>> -static bool start_new_rx_buffer(int offset, unsigned long size, int >>> head) >>> +static bool start_new_rx_buffer(int offset, >>> + unsigned long size, >>> + int head, >>> + bool full_coalesce) >> >> The above is completely incorrect layout ... > Can you elaborate a bit please on "above"? I just realized you're not talking about skb layout but format. I'll fix that. Zoli