From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: Re: [RFC PATCHv1 net-next] xen-netback: always fully coalesce guest Rx packets Date: Tue, 20 Jan 2015 11:34:06 +0000 Message-ID: <1421753646.10440.228.camel@citrix.com> References: <1421157917-31333-1-git-send-email-david.vrabel@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: , , Wei Liu To: David Vrabel Return-path: Received: from smtp02.citrix.com ([66.165.176.63]:43373 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753135AbbATLeI (ORCPT ); Tue, 20 Jan 2015 06:34:08 -0500 In-Reply-To: <1421157917-31333-1-git-send-email-david.vrabel@citrix.com> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, 2015-01-13 at 14:05 +0000, David Vrabel wrote: > Always fully coalesce guest Rx packets into the minimum number of ring > slots. Reducing the number of slots per packet has significant > performance benefits (e.g., 7.2 Gbit/s to 11 Gbit/s in an off-host > receive test). > > However, this does increase the number of grant ops per packet which > decreases performance with some workloads (intrahost VM to VM) > /unless/ grant copy has been optimized for adjacent ops with the same > source or destination (see "grant-table: defer releasing pages > acquired in a grant copy"[1]). > > Do we need to retain the existing path and make the always coalesce > path conditional on a suitable version of Xen? > > [1] http://lists.xen.org/archives/html/xen-devel/2015-01/msg01118.html > > Signed-off-by: David Vrabel Looks good to me, thanks. Based on that plus the conversation in the other subthread: Acked-by: Ian Campbell