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Commit 990f27cc authored by Juergen Gross's avatar Juergen Gross Committed by Greg Kroah-Hartman
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xen/netback: set default upper limit of tx/rx queues to 8 




[ 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: default avatarJuergen Gross <jgross@suse.com>
Reviewed-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: default avatarSasha Levin <alexander.levin@verizon.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 170783f9

drivers/net/xen-netback/netback.c

+4 −2
Original line number Diff line number Diff line
@@ -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,
@@ -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",