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Jonas Rebmann says: ==================== improve multicast join group performance This series seeks to improve performance on updating igmp group memberships such as with IP_ADD_MEMBERSHIP or MCAST_JOIN_SOURCE_GROUP. Our use case was to add 2000 multicast memberships on a TQMLS1046A which took about 3.6 seconds for the membership additions alone. Our userspace reproducer tool was instrumented to log runtimes of the individual setsockopt invocations which clearly indicated quadratic complexity of setting up the membership with regard to the total number of multicast groups to be joined. We used perf to locate the hotspots and subsequently optimized the most costly sections of code. This series includes a patch to Linux igmp handling as well as a patch to the DPAA/Freescale driver. With both patches applied, our memberships can be set up in only about 87 miliseconds, which corresponds to a speedup of around 40. While we have acheived practically linear run-time complexity on the kernel side, a small quadratic factor remains in parts of the freescale driver code which we haven't yet optimized. We have by now payed little attention to the optimization potential in dropping group memberships, yet the dpaa patch applies to joining and leaving groups alike. Overall, this patch series brings great improvements in use cases involving large numbers of multicast groups, particularly when using the fsl_dpa driver, without noteworthy drawbacks in other scenarios. ==================== Signed-off-by: Jonas Rebmann <jre@pengutronix.de> Signed-off-by: David S. Miller <davem@davemloft.net>
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