diff --git a/cpuplugd/config.c b/cpuplugd/config.c
index e48a3913..a3c8c6b7 100644
--- a/cpuplugd/config.c
+++ b/cpuplugd/config.c
@@ -204,6 +204,45 @@ void parse_configfile(char *file)
 	fclose(filp);
 }
 
+void apply_cpu_config(void)
+{
+	/*
+	 * Check that the initial number of cpus is not below the
+	 * minimum
+	 */
+	if (num_cpu_start < cfg.cpu_min &&
+	    get_numcpus() >= cfg.cpu_min) {
+		cpuplugd_debug("The number of online cpus is below ");
+		cpuplugd_debug("the minimum and will be increased.\n");
+		while (get_num_online_cpus() < cfg.cpu_min) {
+			if (hotplug_one_cpu())
+				break;
+		}
+	}
+	if (get_num_online_cpus() > cfg.cpu_max) {
+		cpuplugd_debug("The number of online cpus is above the maximum");
+		cpuplugd_debug(" and will be decreased.\n");
+		while (get_num_online_cpus() > cfg.cpu_max) {
+			if (hotunplug_one_cpu())
+				break;
+		}
+	}
+	if (cfg.cpu_min > get_numcpus()) {
+		/*
+		 * This check only works if nobody used the
+		 * additional_cpus in the boot parameter section
+		 */
+		cpuplugd_debug("The minimum amount of cpus is above the ");
+		cpuplugd_debug("number of available cpus.\n");
+		cpuplugd_exit("Detected %d available cpus\n", get_numcpus());
+	}
+	if (get_num_online_cpus() < cfg.cpu_min) {
+		cpuplugd_debug("Failed to set the number of online cpus to ");
+		cpuplugd_debug("the minimum. ");
+		cpuplugd_exit("Aborting.\n");
+	}
+}
+
 /*
  * Check if the required settings are found in the configuration file.
  * "Autodetect" if cpu and/or memory hotplug configuration entries
@@ -261,44 +300,23 @@ void check_config()
 	/*
 	* Save the number of online cpus and the cmm_pagesize at startup,
 	* so that we can enable exactly the same amount when the daemon ends
+	*
+	* Don't adjust cpus if system is on vertical polarization
 	*/
-	if (cpu) {
-		num_cpu_start = get_num_online_cpus();
-		cpuplugd_debug("Daemon started with %d active cpus.\n",
-			       num_cpu_start);
-		/*
-		 * Check that the initial number of cpus is not below the
-		 * minimum
-		 */
-		if (num_cpu_start < cfg.cpu_min &&
-		    get_numcpus() >= cfg.cpu_min) {
-			cpuplugd_debug("The number of online cpus is below "
-				       "the minimum and will be increased.\n");
-			while (get_num_online_cpus() < cfg.cpu_min) {
-				if (hotplug_one_cpu())
-					break;
-			}
-		}
-		if (get_num_online_cpus() > cfg.cpu_max) {
-			cpuplugd_debug("The number of online cpus is above the maximum"
-				       " and will be decreased.\n");
-			while (get_num_online_cpus() > cfg.cpu_max) {
-				if (hotunplug_one_cpu())
-					break;
-			}
-		}
-		if (cfg.cpu_min > get_numcpus())
-			/*
-			 * This check only works if nobody used the
-			 * additional_cpus in the boot parameter section
-			 */
-			cpuplugd_exit("The minimum amount of cpus is above "
-				      "the number of available cpus.\n"
-				      "Detected %d available cpus\n",
-				      get_numcpus());
-		if (get_num_online_cpus() < cfg.cpu_min)
-			cpuplugd_exit("Failed to set the number of online "
-				      "cpus to the minimum. Aborting.\n");
+	saved_polarization = get_polarization();
+	num_cpu_start = get_num_online_cpus();
+	cpuplugd_debug("Daemon started with %d active cpus.\n",
+		       num_cpu_start);
+	if (saved_polarization < 0) {
+		cpuplugd_debug("Daemon couldn't determine system polarization\n");
+		cpuplugd_debug("Starting without evaluating cpu rules\n");
+	} else if (saved_polarization == PLR_VERTICAL) {
+		cpuplugd_debug("Daemon started with vertical polarization.\n");
+		cpuplugd_debug("Cpu adjustments won't be made until system ");
+		cpuplugd_debug("is in horizontal polarization\n");
+	} else if (saved_polarization == PLR_HORIZONTAL &&
+		   cpu == 1) {
+		apply_cpu_config();
 	}
 	if (memory == 1) {
 		/*
diff --git a/cpuplugd/cpu.c b/cpuplugd/cpu.c
index 54a6f349..97092c16 100644
--- a/cpuplugd/cpu.c
+++ b/cpuplugd/cpu.c
@@ -78,6 +78,23 @@ int get_num_online_cpus(void)
 	return number;
 }
 
+/*
+ * get_polarization() - return system polarization
+ */
+int get_polarization(void)
+{
+	int polarization;
+	char *path;
+
+	path = util_path_sysfs("devices/system/cpu/dispatching");
+	if (util_file_read_i(&polarization, NUM_BASE, path) < 0) {
+		polarization = -1;
+		cpuplugd_debug("failed to read system polarization\n");
+	}
+	free(path);
+	return polarization;
+}
+
 /*
  * is_cpu_hotpluggable() - check if cpuhotplug operations are supported
  * for the given cpu.
@@ -206,8 +223,6 @@ void reactivate_cpus(void)
 	int cpuid, nc, count, i;
 	char *path;
 
-	/* suppress verbose messages on exit */
-	debug = 0;
 	/*
 	 * Only enable the number of cpus which where available at
 	 * daemon startup time by checking num_cpu_start.
diff --git a/cpuplugd/cpuplugd.h b/cpuplugd/cpuplugd.h
index 2b06cd10..dff3fc34 100644
--- a/cpuplugd/cpuplugd.h
+++ b/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);
diff --git a/cpuplugd/daemon.c b/cpuplugd/daemon.c
index 9820eba5..0b618972 100644
--- a/cpuplugd/daemon.c
+++ b/cpuplugd/daemon.c
@@ -149,6 +149,8 @@ void clean_up()
 	cpuplugd_info("terminated\n");
 	remove(pid_file);
 	remove(LOCKFILE);
+	/* suppress verbose messages on exit */
+	debug = 0;
 	reactivate_cpus();
 	if (memory)
 		cleanup_cmm();
@@ -163,6 +165,8 @@ void kill_daemon(int UNUSED(a))
 	cpuplugd_info("shutting down\n");
 	remove(pid_file);
 	remove(LOCKFILE);
+	/* suppress verbose messages on exit */
+	debug = 0;
 	reactivate_cpus();
 	if (memory)
 		cleanup_cmm();
diff --git a/cpuplugd/main.c b/cpuplugd/main.c
index 658ca91a..de286205 100644
--- a/cpuplugd/main.c
+++ b/cpuplugd/main.c
@@ -54,12 +54,12 @@ struct config cfg = {
 	.hotunplug = NULL,
 };
 
-int num_cpu_start, memory, cpu, reload_pending;
-long cmm_pagesize_start;
-unsigned long meminfo_size, vmstat_size, cpustat_size, varinfo_size;
-char *meminfo, *vmstat, *cpustat, *varinfo;
-double *timestamps;
 unsigned int history_max, history_current, history_prev, sym_names_count;
+unsigned long meminfo_size, vmstat_size, cpustat_size, varinfo_size;
+int num_cpu_start, memory, cpu, reload_pending, saved_polarization;
+char *meminfo, *vmstat, *cpustat, *varinfo;
+long cmm_pagesize_start;
+double *timestamps;
 
 static struct symbols symbols;
 static jmp_buf jmpenv;
@@ -77,8 +77,29 @@ static void eval_cpu_rules(void)
 {
 	double diffs[CPUSTATS], diffs_total, percent_factor;
 	char *procinfo_current, *procinfo_prev;
-	int nr_cpus, on_off;
+	int nr_cpus, on_off, polarization;
 
+	polarization = get_polarization();
+	if (polarization < 0) {
+		cpuplugd_debug("couldn't determine system polarization\n");
+		cpuplugd_debug("skipping cpu rule evaluation\n");
+		return;
+	}
+	if (saved_polarization != polarization) {
+		saved_polarization = polarization;
+		if (polarization == PLR_VERTICAL) {
+			/* revert cpu hotplug adjustments after switching from horizontal */
+			reactivate_cpus();
+		} else if (polarization == PLR_HORIZONTAL) {
+			/* reapply cpu config after switching from vertical */
+			apply_cpu_config();
+		}
+	}
+	if (polarization == PLR_VERTICAL) {
+		cpuplugd_debug("system is running vertical polarization\n");
+		cpuplugd_debug("cpuplugd won't make cpu adjustments\n");
+		return;
+	}
 	nr_cpus = get_numcpus();
 	procinfo_current = cpustat + history_current * cpustat_size;
 	procinfo_prev = cpustat + history_prev * cpustat_size;
@@ -157,7 +178,6 @@ static void eval_cpu_rules(void)
 		printf("\n");
 		printf("---------------------------------------------\n");
 	}
-
 	on_off = 0;
 	/* Evaluate the hotplug rule */
 	if (eval_term(cfg.hotplug, &symbols))
diff --git a/cpuplugd/man/cpuplugd.8 b/cpuplugd/man/cpuplugd.8
index 846db881..5b51bd90 100644
--- a/cpuplugd/man/cpuplugd.8
+++ b/cpuplugd/man/cpuplugd.8
@@ -22,6 +22,9 @@ of active CPUs are reset to the values they had before the cpuplugd was started.
 This program can be used to control the number of CPUs for Linux on z/VM
 and for Linux in LPAR mode. The memory hotplug feature (CMM page pool) applies
 to Linux on z/VM only.
+
+The cpuplugd daemon stops any CPU hot-plug operations when the system switches
+to vertical polarization, thus avoiding possible performance penalties.
 .
 .SH OPTIONS
 .TP