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

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 <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 14:32:51 +01:00 committed by Boris Ostrovsky
parent 566cf877a1
commit 034702a64a
1 changed files with 4 additions and 2 deletions
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6
drivers/net/xen-netfront.c
View File

@ -57,6 +57,7 @@
#include <xen/interface/grant_table.h> #include <xen/interface/grant_table.h>
/* Module parameters */ /* Module parameters */
#define MAX_QUEUES_DEFAULT 8
static unsigned int xennet_max_queues; static unsigned int xennet_max_queues;
module_param_named(max_queues, xennet_max_queues, uint, 0644); module_param_named(max_queues, xennet_max_queues, uint, 0644);
MODULE_PARM_DESC(max_queues, MODULE_PARM_DESC(max_queues,
@ -2164,11 +2165,12 @@ static int __init netif_init(void)
pr_info("Initialising Xen virtual ethernet driver\n"); 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. * specified a value.
*/ */
if (xennet_max_queues == 0) 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); return xenbus_register_frontend(&netfront_driver);
} }