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xen/netback: set default upper limit of tx/rx queues to 8

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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 <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
This commit is contained in:
Juergen Gross 2017-01-10 14:32:52 +01:00 committed by Boris Ostrovsky
parent 034702a64a
commit 56dd5af9bc
1 changed files with 4 additions and 2 deletions
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6
drivers/net/xen-netback/netback.c
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@ -67,6 +67,7 @@ module_param(rx_drain_timeout_msecs, uint, 0444);
unsigned int rx_stall_timeout_msecs = 60000; unsigned int rx_stall_timeout_msecs = 60000;
module_param(rx_stall_timeout_msecs, uint, 0444); module_param(rx_stall_timeout_msecs, uint, 0444);
#define MAX_QUEUES_DEFAULT 8
unsigned int xenvif_max_queues; unsigned int xenvif_max_queues;
module_param_named(max_queues, xenvif_max_queues, uint, 0644); module_param_named(max_queues, xenvif_max_queues, uint, 0644);
MODULE_PARM_DESC(max_queues, MODULE_PARM_DESC(max_queues,
@ -1622,11 +1623,12 @@ static int __init netback_init(void)
if (!xen_domain()) if (!xen_domain())
return -ENODEV; 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. * specified a value.
*/ */
if (xenvif_max_queues == 0) 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) { 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", pr_info("fatal_skb_slots too small (%d), bump it to XEN_NETBK_LEGACY_SLOTS_MAX (%d)\n",