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diff --git a/Documentation/networking/scaling.rst b/Documentation/networking/scaling.rst index 92c9fb46d6..03ae19a689 100644 --- a/Documentation/networking/scaling.rst +++ b/Documentation/networking/scaling.rst @@ -105,6 +105,48 @@ a separate CPU. For interrupt handling, HT has shown no benefit in initial tests, so limit the number of queues to the number of CPU cores in the system. +Dedicated RSS contexts +~~~~~~~~~~~~~~~~~~~~~~ + +Modern NICs support creating multiple co-existing RSS configurations +which are selected based on explicit matching rules. This can be very +useful when application wants to constrain the set of queues receiving +traffic for e.g. a particular destination port or IP address. +The example below shows how to direct all traffic to TCP port 22 +to queues 0 and 1. + +To create an additional RSS context use:: + + # ethtool -X eth0 hfunc toeplitz context new + New RSS context is 1 + +Kernel reports back the ID of the allocated context (the default, always +present RSS context has ID of 0). The new context can be queried and +modified using the same APIs as the default context:: + + # ethtool -x eth0 context 1 + RX flow hash indirection table for eth0 with 13 RX ring(s): + 0: 0 1 2 3 4 5 6 7 + 8: 8 9 10 11 12 0 1 2 + [...] + # ethtool -X eth0 equal 2 context 1 + # ethtool -x eth0 context 1 + RX flow hash indirection table for eth0 with 13 RX ring(s): + 0: 0 1 0 1 0 1 0 1 + 8: 0 1 0 1 0 1 0 1 + [...] + +To make use of the new context direct traffic to it using an n-tuple +filter:: + + # ethtool -N eth0 flow-type tcp6 dst-port 22 context 1 + Added rule with ID 1023 + +When done, remove the context and the rule:: + + # ethtool -N eth0 delete 1023 + # ethtool -X eth0 context 1 delete + RPS: Receive Packet Steering ============================ |