From 56dd5af9bc23d0d5d23bb207c477715b4c2216c5 Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Tue, 10 Jan 2017 14:32:52 +0100 Subject: [PATCH] xen/netback: set default upper limit of tx/rx queues to 8 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 --- 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 47b481095d77..f9bcf4a665bc 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",