From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCHv2 net-next] xen-netback: always fully coalesce guest Rx packets Date: Fri, 23 Jan 2015 17:57:18 -0800 (PST) Message-ID: <20150123.175718.1746060859200808793.davem@davemloft.net> References: <1421765392-30303-1-git-send-email-david.vrabel@citrix.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, xen-devel@lists.xenproject.org, ian.campbell@citrix.com, wei.liu2@citrix.com To: david.vrabel@citrix.com Return-path: Received: from shards.monkeyblade.net ([149.20.54.216]:52870 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751883AbbAXB5U (ORCPT ); Fri, 23 Jan 2015 20:57:20 -0500 In-Reply-To: <1421765392-30303-1-git-send-email-david.vrabel@citrix.com> Sender: netdev-owner@vger.kernel.org List-ID: From: David Vrabel Date: Tue, 20 Jan 2015 14:49:52 +0000 > Always fully coalesce guest Rx packets into the minimum number of ring > slots. Reducing the number of slots per packet has significant > performance benefits when receiving off-host traffic. > > Results from XenServer's performance benchmarks: > > Baseline Full coalesce > Interhost VM receive 7.2 Gb/s 11 Gb/s > Interhost aggregate 24 Gb/s 24 Gb/s > Intrahost single stream 14 Gb/s 14 Gb/s > Intrahost aggregate 34 Gb/s 34 Gb/s > > However, this can increase the number of grant ops per packet which > decreases performance of backend (dom0) to VM traffic (by ~10%) > /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] expected in Xen 4.6). > > [1] http://lists.xen.org/archives/html/xen-devel/2015-01/msg01118.html > > Signed-off-by: David Vrabel > Acked-by: Ian Campbell > --- > Changes in v2: > - Updated commit message with better results. Applied, thanks David.