From mboxrd@z Thu Jan 1 00:00:00 1970 From: Juergen Gross Subject: [PATCH 1/2] xen/netfront: set default upper limit of tx/rx queues to 8 Date: Tue, 10 Jan 2017 14:32:51 +0100 Message-ID: <20170110133252.5346-2-jgross@suse.com> References: <20170110133252.5346-1-jgross@suse.com> Cc: boris.ostrovsky@oracle.com, wei.liu2@citrix.com, paul.durrant@citrix.com, Juergen Gross To: linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, netdev@vger.kernel.org Return-path: In-Reply-To: <20170110133252.5346-1-jgross@suse.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org The default for the number of tx/rx queues of one interface is the number of vcpus 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-netfront.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c index a479cd9..490c865 100644 --- a/drivers/net/xen-netfront.c +++ b/drivers/net/xen-netfront.c @@ -57,6 +57,7 @@ #include /* Module parameters */ +#define MAX_QUEUES_DEFAULT 8 static unsigned int xennet_max_queues; module_param_named(max_queues, xennet_max_queues, uint, 0644); MODULE_PARM_DESC(max_queues, @@ -2164,11 +2165,12 @@ static int __init netif_init(void) pr_info("Initialising Xen virtual ethernet driver\n"); - /* Allow as many queues as there are CPUs if user has not + /* Allow as many queues as there are CPUs inut max. 8 if user has not * specified a value. */ if (xennet_max_queues == 0) - xennet_max_queues = num_online_cpus(); + xennet_max_queues = min_t(unsigned int, MAX_QUEUES_DEFAULT, + num_online_cpus()); return xenbus_register_frontend(&netfront_driver); } -- 2.10.2