cpuplugd: Halt cpu hotplugging on vertical polarization

On vertical polarization, kernel can be adjusting CPU capacities
dynamically, and cpuplugd can interfere this with hotplug operations
causing performance degradation. To prevent this, check if system has
switched its polarization state, and act accordingly.
If system is on vertical polarization when daemon starts, no CPU hotplug
action is triggered. If system changes to vertical polarization during
daemon runtime, revert cpuhotplug adjustments and stop further CPU
hotplug actions. If system switches back to horizontal polarization
during runtime of the daemon, start evaluating CPU hotplug rules and
trigger adjustments.

Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Signed-off-by: Mete Durlu <meted@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

cpuplugd/cpuplugd.h

@@ -38,6 +38,8 @@
 #define MAX_VARNAME	128
 #define MAX_LINESIZE	2048
 #define CPUSTATS	10
+#define PLR_HORIZONTAL	0
+#define PLR_VERTICAL	1
 
 /*
  *  Precedence of C operators
@@ -176,9 +178,11 @@ extern unsigned int history_max;
 extern unsigned int history_current;
 extern struct symbol_names sym_names[];
 extern unsigned int sym_names_count;
+extern int saved_polarization;
 
 int get_numcpus();
 int get_num_online_cpus();
+int get_polarization(void);
 void get_loadavg_runnable(double *loadavg, double *runnable);
 void clean_up();
 void reactivate_cpus();
@@ -204,6 +208,7 @@ void reload_daemon(void);
 int daemonize(void);
 int check_cmmfiles(void);
 void check_config();
+void apply_cpu_config(void);
 void set_cmm_pages(long size);
 int check_lpar();
 void setup_history(void);