From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753009AbdKMMz4 (ORCPT ); Mon, 13 Nov 2017 07:55:56 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:48816 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752936AbdKMMzx (ORCPT ); Mon, 13 Nov 2017 07:55:53 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Juergen Gross , Boris Ostrovsky , Sasha Levin Subject: [PATCH 3.18 02/28] xen/netback: set default upper limit of tx/rx queues to 8 Date: Mon, 13 Nov 2017 13:54:56 +0100 Message-Id: <20171113125401.002264947@linuxfoundation.org> X-Mailer: git-send-email 2.15.0 In-Reply-To: <20171113125400.803506921@linuxfoundation.org> References: <20171113125400.803506921@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Juergen Gross [ Upstream commit 56dd5af9bc23d0d5d23bb207c477715b4c2216c5 ] The default for the maximum number of tx/rx queues of one interface is the number of cpus of the system today. As each queue pair reserves 512 grant pages this default consumes a ridiculous number of grants for large guests. Limit the queue number to 8 as default. This value can be modified via a module parameter if required. Signed-off-by: Juergen Gross Reviewed-by: Boris Ostrovsky Signed-off-by: Boris Ostrovsky Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/net/xen-netback/netback.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c @@ -67,6 +67,7 @@ module_param(rx_drain_timeout_msecs, uin unsigned int rx_stall_timeout_msecs = 60000; module_param(rx_stall_timeout_msecs, uint, 0444); +#define MAX_QUEUES_DEFAULT 8 unsigned int xenvif_max_queues; module_param_named(max_queues, xenvif_max_queues, uint, 0644); MODULE_PARM_DESC(max_queues, @@ -2189,11 +2190,12 @@ static int __init netback_init(void) if (!xen_domain()) return -ENODEV; - /* Allow as many queues as there are CPUs if user has not + /* Allow as many queues as there are CPUs but max. 8 if user has not * specified a value. */ if (xenvif_max_queues == 0) - xenvif_max_queues = num_online_cpus(); + xenvif_max_queues = min_t(unsigned int, MAX_QUEUES_DEFAULT, + num_online_cpus()); if (fatal_skb_slots < XEN_NETBK_LEGACY_SLOTS_MAX) { pr_info("fatal_skb_slots too small (%d), bump it to XEN_NETBK_LEGACY_SLOTS_MAX (%d)\n",