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| author | Eric Dumazet <edumazet@google.com> | 2014-11-16 06:23:05 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2014-11-16 15:59:11 -0500 |
| commit | 960fb622f85180f36d3aff82af53e2be3db2f888 (patch) | |
| tree | c567b80d26270e3d4a3437c9710be6ca0f1eddc3 /Documentation/sysctl | |
| parent | ca245024349c0d44434a6381583b99f0eb559c7c (diff) | |
| download | lwn-960fb622f85180f36d3aff82af53e2be3db2f888.tar.gz lwn-960fb622f85180f36d3aff82af53e2be3db2f888.zip | |
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')
| -rw-r--r-- | Documentation/sysctl/net.txt | 22 |
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 ---------------------- |