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authorEric Dumazet <edumazet@google.com>2014-11-16 06:23:05 -0800
committerDavid S. Miller <davem@davemloft.net>2014-11-16 15:59:11 -0500
commit960fb622f85180f36d3aff82af53e2be3db2f888 (patch)
treec567b80d26270e3d4a3437c9710be6ca0f1eddc3 /Documentation/sysctl/net.txt
parentca245024349c0d44434a6381583b99f0eb559c7c (diff)
net: provide a per host RSS key generic infrastructure
RSS (Receive Side Scaling) typically uses Toeplitz hash and a 40 or 52 bytes RSS key. Some drivers use a constant (and well known key), some drivers use a random key per port, making bonding setups hard to tune. Well known keys increase attack surface, considering that number of queues is usually a power of two. This patch provides infrastructure to help drivers doing the right thing. netdev_rss_key_fill() should be used by drivers to initialize their RSS key, even if they provide ethtool -X support to let user redefine the key later. A new /proc/sys/net/core/netdev_rss_key file can be used to get the host RSS key even for drivers not providing ethtool -x support, in case some applications want to precisely setup flows to match some RX queues. Tested: myhost:~# cat /proc/sys/net/core/netdev_rss_key 11:63:99:bb:79:fb:a5:a7:07:45:b2:20:bf:02:42:2d:08:1a:dd:19:2b:6b:23:ac:56:28:9d:70:c3:ac:e8:16:4b:b7:c1:10:53:a4:78:41:36:40:74:b6:15:ca:27:44:aa:b3:4d:72 myhost:~# ethtool -x eth0 RX flow hash indirection table for eth0 with 8 RX ring(s): 0: 0 1 2 3 4 5 6 7 RSS hash key: 11:63:99:bb:79:fb:a5:a7:07:45:b2:20:bf:02:42:2d:08:1a:dd:19:2b:6b:23:ac:56:28:9d:70:c3:ac:e8:16:4b:b7:c1:10:53:a4:78:41 Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'Documentation/sysctl/net.txt')
-rw-r--r--Documentation/sysctl/net.txt22
1 files changed, 22 insertions, 0 deletions
diff --git a/Documentation/sysctl/net.txt b/Documentation/sysctl/net.txt
index e26c607468a6..666594b43cff 100644
--- a/Documentation/sysctl/net.txt
+++ b/Documentation/sysctl/net.txt
@@ -142,6 +142,28 @@ netdev_max_backlog
Maximum number of packets, queued on the INPUT side, when the interface
receives packets faster than kernel can process them.
+netdev_rss_key
+--------------
+
+RSS (Receive Side Scaling) enabled drivers use a 40 bytes host key that is
+randomly generated.
+Some user space might need to gather its content even if drivers do not
+provide ethtool -x support yet.
+
+myhost:~# cat /proc/sys/net/core/netdev_rss_key
+84:50:f4:00:a8:15:d1:a7:e9:7f:1d:60:35:c7:47:25:42:97:74:ca:56:bb:b6:a1:d8: ... (52 bytes total)
+
+File contains nul bytes if no driver ever called netdev_rss_key_fill() function.
+Note:
+/proc/sys/net/core/netdev_rss_key contains 52 bytes of key,
+but most drivers only use 40 bytes of it.
+
+myhost:~# ethtool -x eth0
+RX flow hash indirection table for eth0 with 8 RX ring(s):
+ 0: 0 1 2 3 4 5 6 7
+RSS hash key:
+84:50:f4:00:a8:15:d1:a7:e9:7f:1d:60:35:c7:47:25:42:97:74:ca:56:bb:b6:a1:d8:43:e3:c9:0c:fd:17:55:c2:3a:4d:69:ed:f1:42:89
+
netdev_tstamp_prequeue
----------------------