net: RPS: Enable hardware acceleration of RFS

Allow drivers for multiqueue hardware with flow filter tables to
accelerate RFS.  The driver must:

1. Set net_device::rx_cpu_rmap to a cpu_rmap of the RX completion
IRQs (in queue order).  This will provide a mapping from CPUs to the
queues for which completions are handled nearest to them.

2. Implement net_device_ops::ndo_rx_flow_steer.  This operation adds
or replaces a filter steering the given flow to the given RX queue, if
possible.

3. Periodically remove filters for which rps_may_expire_flow() returns
true.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 0 deletions

diff --git a/net/Kconfig b/net/Kconfig
index 72840626284b..79cabf1ee68b 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -221,6 +221,12 @@ config RPS
         depends on SMP && SYSFS && USE_GENERIC_SMP_HELPERS
         default y
 
+config RFS_ACCEL
+        boolean
+        depends on RPS && GENERIC_HARDIRQS
+        select CPU_RMAP
+        default y
+
 config XPS
         boolean
         depends on SMP && SYSFS && USE_GENERIC_SMP_HELPERS