Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752965Ab3J3Jj5 (ORCPT ); Wed, 30 Oct 2013 05:39:57 -0400 Received: from nat28.tlf.novell.com ([130.57.49.28]:38669 "EHLO nat28.tlf.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751650Ab3J3Jj4 convert rfc822-to-8bit (ORCPT ); Wed, 30 Oct 2013 05:39:56 -0400 Message-Id: <5270E1F902000078000FDFCA@nat28.tlf.novell.com> X-Mailer: Novell GroupWise Internet Agent 12.0.2 Date: Wed, 30 Oct 2013 09:39:53 +0000 From: "Jan Beulich" To: "Zoltan Kiss" Cc: , , , , , Subject: Re: [Xen-devel] [PATCH net-next RFC 3/5] xen-netback: Remove old TX grant copy definitons References: <1383094220-14775-1-git-send-email-zoltan.kiss@citrix.com> <1383094220-14775-4-git-send-email-zoltan.kiss@citrix.com> In-Reply-To: <1383094220-14775-4-git-send-email-zoltan.kiss@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 780 Lines: 19 >>> On 30.10.13 at 01:50, Zoltan Kiss wrote: > These became obsolate with grant mapping. I didn't look at this in detail, but I'm surprised you can get away without any copying: For one, the header part needs copying anyway, so you'd pointlessly map and then copy it if it's small enough. And second you need to be prepared for the frontend to hand you more slots than you can fit in MAX_SKB_FRAGS (namely when MAX_SKB_FRAGS < XEN_NETIF_NR_SLOTS_MIN), which you can't handle with mapping alone afaict. Jan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/