netfilter: ipvs: Add configurations of Maglev hashing

To build the maglev hashing scheduler, add some configuration
to Kconfig and Makefile.

 - The compile configurations of MH are added to the Kconfig.

 - The MH build rule is added to the Makefile.

Signed-off-by: Inju Song <inju.song@navercorp.com>
Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>

net/netfilter/ipvs/Kconfig

@@ -225,6 +225,25 @@ config	IP_VS_SH
 	  If you want to compile it in kernel, say Y. To compile it as a
 	  module, choose M here. If unsure, say N.
 
+config	IP_VS_MH
+	tristate "maglev hashing scheduling"
+	---help---
+	  The maglev consistent hashing scheduling algorithm provides the
+	  Google's Maglev hashing algorithm as a IPVS scheduler. It assigns
+	  network connections to the servers through looking up a statically
+	  assigned special hash table called the lookup table. Maglev hashing
+	  is to assign a preference list of all the lookup table positions
+	  to each destination.
+
+	  Through this operation, The maglev hashing gives an almost equal
+	  share of the lookup table to each of the destinations and provides
+	  minimal disruption by using the lookup table. When the set of
+	  destinations changes, a connection will likely be sent to the same
+	  destination as it was before.
+
+	  If you want to compile it in kernel, say Y. To compile it as a
+	  module, choose M here. If unsure, say N.
+
 config	IP_VS_SED
 	tristate "shortest expected delay scheduling"
 	---help---
@@ -266,6 +285,24 @@ config IP_VS_SH_TAB_BITS
 	  needs to be large enough to effectively fit all the destinations
 	  multiplied by their respective weights.
 
+comment 'IPVS MH scheduler'
+
+config IP_VS_MH_TAB_INDEX
+	int "IPVS maglev hashing table index of size (the prime numbers)"
+	range 8 17
+	default 12
+	---help---
+	  The maglev hashing scheduler maps source IPs to destinations
+	  stored in a hash table. This table is assigned by a preference
+	  list of the positions to each destination until all slots in
+	  the table are filled. The index determines the prime for size of
+	  the table as 251, 509, 1021, 2039, 4093, 8191, 16381, 32749,
+	  65521 or 131071. When using weights to allow destinations to
+	  receive more connections, the table is assigned an amount
+	  proportional to the weights specified. The table needs to be large
+	  enough to effectively fit all the destinations multiplied by their
+	  respective weights.
+
 comment 'IPVS application helper'
 
 config	IP_VS_FTP

net/netfilter/ipvs/Makefile

@@ -33,6 +33,7 @@ obj-$(CONFIG_IP_VS_LBLC) += ip_vs_lblc.o
 obj-$(CONFIG_IP_VS_LBLCR) += ip_vs_lblcr.o
 obj-$(CONFIG_IP_VS_DH) += ip_vs_dh.o
 obj-$(CONFIG_IP_VS_SH) += ip_vs_sh.o
+obj-$(CONFIG_IP_VS_MH) += ip_vs_mh.o
 obj-$(CONFIG_IP_VS_SED) += ip_vs_sed.o
 obj-$(CONFIG_IP_VS_NQ) += ip_vs_nq.o