f67f6a3d72b24f0d8bf9a295a27ea448e author Cyrill Gorcunov 1305848749 -0700 committer Ingo Molnar 1305891669 +0200 x86, x2apic: Minimize IPI register writes using cluster groups In the case of x2apic cluster mode we can group IPI register writes based on the cluster group instead of individual per-cpu destination messages. This reduces the apic register writes and reduces the amount of IPI messages (in the best case we can reduce it by a factor of 16). With this change, the cost of flush_tlb_others(), with the flush tlb IPI being sent from a cpu in the socket-1 to all the logical cpus in socket-2 (on a Westmere-EX system that has 20 logical cpus in a socket) is 3x times better now (compared to the former 'send one-by-one' algorithm). Signed-off-by: Cyrill Gorcunov Signed-off-by: Suresh Siddha Cc: steiner@sgi.com Cc: yinghai@kernel.org Link: http://lkml.kernel.org/r/20110519234637.512271057@sbsiddha-MOBL3.sc.intel.com Signed-off-by: Ingo Molnar .