linux-kernel - [PATCH 4.4 04/56] xen/netback: set default upper limit of tx/rx queues to 8

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20171113125558.222896134@linuxfoundation.org>
Date:   Mon, 13 Nov 2017 13:55:28 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Juergen Gross <jgross@...e.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 4.4 04/56] xen/netback: set default upper limit of tx/rx queues to 8

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Juergen Gross <jgross@...e.com>


[ 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: Juergen Gross <jgross@...e.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/net/xen-netback/netback.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -67,6 +67,7 @@ module_param(rx_drain_timeout_msecs, uin
 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,
@@ -2157,11 +2158,12 @@ 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",