[PATCH v3 8/9] powerpc/xive: Map one IPI interrupt per node

[Cédric Le Goater]

> I gave the patch below a try and we are reaching the same results, 
> even better. The simplest solution is always the best. Nick, you 
> should send that single patch.

FYI, here are results in a KVM guests with pinned vCPUs.

 * P9 DD2.2 - 2s * 64 threads - KVM guest :


                            IPI/sys                           IPI/chip
 -----------   --------------------------------   --------------------------------
                           unhandled                          unhandled               	
 chips  cpus   noirqdebug  detection              noirqdebug  detection 	    
 -----------   --------------------------------   --------------------------------
 1      0-15     4.152813   4.084240   4.061028     4.097700   4.042539   4.008314
        0-31     8.186328   8.157970   7.937127     8.277942   8.019539   7.831189
        0-47    11.391635  11.232960  11.017530    11.278048  10.994501  10.889347
        0-63    13.907476  14.022307  11.460280    13.933946  13.506828  11.369188
 2      0-79    18.105276  18.084463   8.376047    18.069176  17.587916  15.477006
        0-95    22.100683  22.265763   7.338229    22.084006  21.588463  19.502192
        0-111   25.305948  25.473068   6.716235    25.429261  24.607570  22.733253
        0-127   27.814449  28.029029   6.222736    27.960119  27.253432  23.884916

                              

The three columns "IPI/chip" are results with this series. "IPI/sys" are 
without. The "unhandled detection" columns are with Nick's patch.

C.