From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161523AbdAJNdD (ORCPT ); Tue, 10 Jan 2017 08:33:03 -0500 Received: from mx2.suse.de ([195.135.220.15]:40889 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1763324AbdAJNc7 (ORCPT ); Tue, 10 Jan 2017 08:32:59 -0500 From: Juergen Gross To: linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, netdev@vger.kernel.org Cc: boris.ostrovsky@oracle.com, wei.liu2@citrix.com, paul.durrant@citrix.com, Juergen Gross Subject: [PATCH 2/2] xen/netback: set default upper limit of tx/rx queues to 8 Date: Tue, 10 Jan 2017 14:32:52 +0100 Message-Id: <20170110133252.5346-3-jgross@suse.com> X-Mailer: git-send-email 2.10.2 In-Reply-To: <20170110133252.5346-1-jgross@suse.com> References: <20170110133252.5346-1-jgross@suse.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- drivers/net/xen-netback/netback.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c index 47b4810..f9bcf4a 100644 --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c @@ -67,6 +67,7 @@ module_param(rx_drain_timeout_msecs, uint, 0444); 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, @@ -1622,11 +1623,12 @@ 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", -- 2.10.2