linux-kernel - [PATCH v4 net-next 2/2 tuntap: Increase the number of queues in tun.

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: <1420522756-15127-3-git-send-email-pagupta@redhat.com>
Date:	Tue,  6 Jan 2015 11:09:16 +0530
From:	Pankaj Gupta <pagupta@...hat.com>
To:	linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Cc:	davem@...emloft.net, jasowang@...hat.com, mst@...hat.com,
	dgibson@...hat.com, vfalico@...il.com, edumazet@...gle.com,
	vyasevic@...hat.com, hkchu@...gle.com, wuzhy@...ux.vnet.ibm.com,
	xemul@...allels.com, therbert@...gle.com,
	bhutchings@...arflare.com, xii@...gle.com,
	stephen@...workplumber.org, jiri@...nulli.us,
	sergei.shtylyov@...entembedded.com,
	Pankaj Gupta <pagupta@...hat.com>
Subject: [PATCH v4 net-next 2/2 tuntap: Increase the number of queues in tun.

Networking under kvm works best if we allocate a per-vCPU RX and TX
queue in a virtual NIC. This requires a per-vCPU queue on the host side.

It is now safe to increase the maximum number of queues.
Preceding patch: 'net: allow large number of rx queues'
made sure this won't cause failures due to high order memory
allocations. Increase it to 256: this is the max number of vCPUs
KVM supports.

Size of tun_struct changes from 8512 to 10496 after this patch. This keeps 
pages allocated for tun_struct before and after the patch to 3. 

Signed-off-by: Pankaj Gupta <pagupta@...hat.com>
Reviewed-by: David Gibson <dgibson@...hat.com>
---
 drivers/net/tun.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index e3fa65a..a19dc5f8 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -113,10 +113,11 @@ struct tap_filter {
 	unsigned char	addr[FLT_EXACT_COUNT][ETH_ALEN];
 };
 
-/* DEFAULT_MAX_NUM_RSS_QUEUES were chosen to let the rx/tx queues allocated for
- * the netdevice to be fit in one page. So we can make sure the success of
- * memory allocation. TODO: increase the limit. */
-#define MAX_TAP_QUEUES DEFAULT_MAX_NUM_RSS_QUEUES
+/* MAX_TAP_QUEUES 256 is chosen to allow rx/tx queues to be equal
+ * to max number of vCPUS in guest. Also, we are making sure here
+ * queue memory allocation do not fail.
+ */
+#define MAX_TAP_QUEUES 256
 #define MAX_TAP_FLOWS  4096
 
 #define TUN_FLOW_EXPIRE (3 * HZ)
-- 
1.8.3.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/