From 034702a64a6692a8d5d0d9630064a014fc633728 Mon Sep 17 00:00:00 2001
From: Juergen Gross <jgross@suse.com>
Date: Tue, 10 Jan 2017 14:32:51 +0100
Subject: [PATCH] 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>
---
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 8315fe73ecd04..7ce5d2f96b515 100644
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -57,6 +57,7 @@
#include <xen/interface/grant_table.h>
/* 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);
}
--
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